ANIMA WG                                                     M. Pritikin
Internet-Draft                                                     Cisco
Intended status: Standards Track                           M. Richardson
Expires: January 4, April 15, 2018                                              SSW
                                                            M. Behringer
                                                                   Cisco
                                                            S. Bjarnason
                                                                   Cisco
                                                          Arbor Networks
                                                               K. Watsen
                                                        Juniper Networks
                                                            July 3,
                                                        October 12, 2017

        Bootstrapping Remote Secure Key Infrastructures (BRSKI)
               draft-ietf-anima-bootstrapping-keyinfra-07
               draft-ietf-anima-bootstrapping-keyinfra-08

Abstract

   This document specifies automated bootstrapping of a remote secure
   key infrastructure (BRSKI) using vendor installed X.509 certificate,
   in combination with a vendor's authorizing service, both online and
   offline.  Bootstrapping a new device can occur using a routable
   address and a cloud service, or using only link-local connectivity,
   or on limited/disconnected networks.  Support for lower security
   models, including devices with minimal identity, is described for
   legacy reasons but not encouraged.  Bootstrapping is complete when
   the cryptographic identity of the new key infrastructure is
   successfully deployed to the device but the established secure
   connection can be used to deploy a locally issued certificate to the
   device as well.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Other Bootstrapping Approaches  . . . . . . . . . . . . .   4
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
     1.3.  Scope of solution . . . . . . . . . . . . . . . . . . . .   7   8
     1.4.  Leveraging the new key infrastructure / next steps  . . .   9
   2.  Architectural Overview  . . . . . . . . . . . . . . . . . . .   9
     2.1.  Secure Imprinting using Vouchers  Behavior of a Pledge  . . . . . . . . . . . .  10
     2.2.  Initial Device Identifier . . . . . .  11
     2.2.  Secure Imprinting using Vouchers  . . . . . . . . . . . .  10  12
     2.3.  Protocol Flow .  Initial Device Identifier . . . . . . . . . . . . . . . .  13
     2.4.  Protocol Flow . . . . .  12
     2.4.  Lack of realtime clock . . . . . . . . . . . . . . . . .  14
     2.5.  Cloud Registrar
       2.4.1.  Architectural component: Pledge . . . . . . . . . . .  16
       2.4.2.  Architectural component: Circuit Proxy  . . . . . . .  16
       2.4.3.  Architectural component: Domain Registrar . . . . .  15
   3.  Protocol Details .  16
       2.4.4.  Architectural component: Vendor Service . . . . . . .  16
     2.5.  Lack of realtime clock  . . . . . . . . . . . . . .  15
     3.1.  Discovery . . .  16
     2.6.  Cloud Registrar . . . . . . . . . . . . . . . . . . . . .  17
       3.1.1.  Proxy Discovery Protocol Details
     2.7.  Determining the MASA to contact . . . . . . . . . .  18
       3.1.2.  Registrar Discovery Protocol Details . . .  17
   3.  Voucher Request artifact  . . . . .  18
     3.2.  Request Voucher from the Registrar . . . . . . . . . . .  19
     3.3.  Request Voucher from MASA . .  18
     3.1.  Tree Diagram  . . . . . . . . . . . . . .  20
     3.4.  Voucher Response . . . . . . . .  18
     3.2.  Examples  . . . . . . . . . . . .  23
       3.4.1.  Completing authentication of Provisional TLS
               connection . . . . . . . . . . . .  19
     3.3.  YANG Module . . . . . . . . .  24
     3.5.  Voucher Status Telemetry . . . . . . . . . . . . . .  21
   4.  Proxy details . .  25
     3.6.  MASA authorization log Request . . . . . . . . . . . . .  26
     3.7.  MASA authorization log Response . . . . . . . . .  23
     4.1.  Pledge discovery of Proxy . . . .  26
     3.8.  EST Integration for PKI bootstrapping . . . . . . . . . .  27
       3.8.1.  EST Distribution of CA Certificates . .  24
       4.1.1.  Proxy Grasp announcements . . . . . . .  28
       3.8.2.  EST CSR Attributes . . . . . . .  25
     4.2.  CoAP connection to Registrar  . . . . . . . . . .  28
       3.8.3.  EST Client Certificate Request . . . .  26
     4.3.  HTTPS proxy connection to Registrar . . . . . . .  29
       3.8.4.  Enrollment Status Telemetry . . . .  26
     4.4.  Proxy discovery of Registrar  . . . . . . . . .  29
       3.8.5.  EST over CoAP . . . . .  26
   5.  Protocol Details  . . . . . . . . . . . . . . .  30
   4.  Reduced security operational modes . . . . . . .  27
     5.1.  BRSKI-EST TLS establishment details . . . . . .  30
     4.1.  Trust Model . . . . .  29
     5.2.  Pledge Requests Voucher from the Registrar  . . . . . . .  30
     5.3.  BRSKI-MASA TLS establishment details  . . . . . . . . . .  31
     5.4.  Registrar Requests Voucher from MASA  .  30
     4.2.  Pledge security reductions . . . . . . . . .  31
     5.5.  Voucher Response  . . . . . .  31
     4.3.  Registrar security reductions . . . . . . . . . . . . . .  32
     4.4.  MASA security reductions  34
       5.5.1.  Completing authentication of Provisional TLS
               connection  . . . . . . . . . . . . . . . .  33
   5.  IANA Considerations . . . . .  35
     5.6.  Voucher Status Telemetry  . . . . . . . . . . . . . . . .  34
     5.1.  PKIX Registry  36
     5.7.  MASA authorization log Request  . . . . . . . . . . . . .  37
       5.7.1.  MASA authorization log Response . . . . . . . . .  34
   6.  Security Considerations . .  38
     5.8.  EST Integration for PKI bootstrapping . . . . . . . . . .  39
       5.8.1.  EST Distribution of CA Certificates . . . . . . .  34
   7.  Acknowledgements . .  39
       5.8.2.  EST CSR Attributes  . . . . . . . . . . . . . . . . .  40
       5.8.3.  EST Client Certificate Request  . . .  35
   8.  References . . . . . . . .  41
       5.8.4.  Enrollment Status Telemetry . . . . . . . . . . . . .  41
       5.8.5.  EST over CoAP . . . .  36
     8.1.  Normative References . . . . . . . . . . . . . . . .  42
   6.  Reduced security operational modes  . .  36
     8.2.  Informative References . . . . . . . . . . .  42
     6.1.  Trust Model . . . . . .  38
   Appendix A.  IPv4 operations . . . . . . . . . . . . . . . . .  42
     6.2.  Pledge security reductions  .  39
     A.1.  IPv4 Link Local addresses . . . . . . . . . . . . . .  43
     6.3.  Registrar security reductions . .  39
     A.2.  Use of DHCPv4 . . . . . . . . . . . .  44
     6.4.  MASA security reductions  . . . . . . . . . .  39
   Appendix B.  mDNS / DNSSD proxy discovery options . . . . . .  44
   7.  IANA Considerations . .  39
   Appendix C.  IPIP Join Proxy mechanism . . . . . . . . . . . . .  40
     C.1.  Multiple Join networks on the Join Proxy side . . . . . .  41
     C.2.  Automatic configuration of tunnels on Registrar  45
     7.1.  PKIX Registry . . . . .  41
     C.3.  Proxy Neighbor Discovery by Join Proxy . . . . . . . . .  42
     C.4.  Use of connected sockets; or IP_PKTINFO for CoAP on
           Registrar . . . . . . . .  45
     7.2.  MIME  . . . . . . . . . . . . . . . .  42
     C.5.  Use of socket extension rather than virtual interface . .  42
   Appendix D.  To be deprecated: Consolidation remnants . . . . . .  43
     D.1.  Functional Overview . .  46
     7.3.  Voucher Status Telemetry  . . . . . . . . . . . . . . . .  47
   8.  Security Considerations .  43
       D.1.1.  Behavior of a Pledge . . . . . . . . . . . . . . . .  46
       D.1.2.  Behavior of a Join Proxy . .  47
     8.1.  Freshness in Voucher Requests . . . . . . . . . . . .  52
       D.1.3.  Behavior of the Registrar . .  49
   9.  Acknowledgements  . . . . . . . . . . . .  53
       D.1.4.  Behavior of the MASA Service . . . . . . . . . .  50
   10. References  . .  57
       D.1.5.  Leveraging the new key infrastructure / next steps .  58
       D.1.6.  Interactions with Network Access Control . . . . . .  58
     D.2.  Domain Operator Activities . . . . . . . . . . . . . . .  58
       D.2.1.  Instantiating the Domain Certification Authority .  50
     10.1.  Normative References .  59
       D.2.2.  Instantiating the Registrar . . . . . . . . . . . . .  59
       D.2.3.  Accepting New Entities . . . .  50
     10.2.  Informative References . . . . . . . . . . .  59
       D.2.4.  Automatic Enrollment of Devices . . . . . .  52
   Appendix A.  IPv4 operations  . . . . .  60
       D.2.5.  Secure Network Operations . . . . . . . . . . . . .  53
     A.1.  IPv4 Link Local addresses .  60 . . . . . . . . . . . . . . .  53
     A.2.  Use of DHCPv4 . . . . . . . . . . . . . . . . . . . . . .  54
   Appendix B.  mDNS / DNSSD proxy discovery options . . . . . . . .  54
   Appendix C.  IPIP Join Proxy mechanism  . . . . . . . . . . . . .  55
     C.1.  Multiple Join networks on the Join Proxy side . . . . . .  55
     C.2.  Automatic configuration of tunnels on Registrar . . . . .  56
     C.3.  Proxy Neighbor Discovery by Join Proxy  . . . . . . . . .  56
     C.4.  Use of connected sockets; or IP_PKTINFO for CoAP on
           Registrar . . . . . . . . . . . . . . . . . . . . . . . .  56
     C.5.  Use of socket extension rather than virtual interface . .  57
   Appendix D.  MUD Extension  . . . . . . . . . . . . . . . . . . .  57
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  61  59

1.  Introduction

   BRSKI provides a foundation to securely answer the following
   questions between an element of the network domain called the
   "Registrar" and an unconfigured and untouched device called a
   "Pledge":

   o  Registrar authenticating the Pledge: "Who is this device?  What is
      its identity?"

   o  Registrar authorization the Pledge: "Is it mine?  Do I want it?
      What are the chances it has been compromised?"

   o  Pledge authenticating the Registrar/Domain: "What is this domain's
      identity?"

   o  Pledge authorization the Registrar: "Should I join it?"

   This document details protocols and messages to the endpoints to
   answer the above questions.  The Registrar actions derive from Pledge
   identity, third party cloud service communications, and local access
   control lists.  The Pledge actions derive from a cryptographically
   protected "voucher" message delivered through the Registrar. Registrar but
   originating at a Manufacturer Authorized Signing Authority.

   The syntactic details of vouchers are described in detail in
   [I-D.ietf-anima-voucher].  This document details automated protocol
   mechanisms to obtain vouchers. vouchers, including the definition of a
   necessary 'voucher request' message that is a minor extension to the
   voucher format (see Section 3).

   BRSKI results in the Pledge storing an X.509 root certificate
   sufficient for verifying the Registrar identity.  In the process a
   TLS connection is established which can be directly used for
   Enrollment over Secure Transport (EST).  The Pledge can use these
   credentials to secure additional protocol exchanges.  In effect BRSKI is agile enough to support bootstrapping alternative key provides an
   automated mechanism for the "Bootstrap Distribution of CA
   Certificates" described in [RFC7030] Section 4.1.1 wherein the Pledge
   "MUST [...]. engage a human user to authorize the CA certificate
   using out-of-band" information".  With BRSKI the Pledge now can
   automate this process using the voucher.  Integration with a complete
   EST enrollment is optional but trivial.

   BRSKI is agile enough to support bootstrapping alternative key
   infrastructures, such as a symmetric key solutions, but no such
   system is described in this document.

1.1.  Other Bootstrapping Approaches

   To literally "pull yourself up by the bootstraps" is an impossible
   action.  Similarly the secure establishment of a key infrastructure
   without external help is also an impossibility.  Today it is commonly
   accepted that the initial connections between nodes are insecure,
   until key distribution is complete, or that domain-specific keying
   material is pre-provisioned on each new device in a costly and non-
   scalable manner.  Existing mechanisms are known as non-secured 'Trust
   on First Use' (TOFU) [RFC7435], 'resurrecting duckling'
   [Stajano99theresurrecting] or 'pre-staging'.

   Another approach is to try and minimize user actions during
   bootstrapping.  The enrollment protocol EST [RFC7030] details a set
   of non-autonomic bootstrapping methods in this vein:

   o  using the Implicit Trust Anchor database (not an autonomic
      solution because the URL must be securely distributed),

   o  engaging a human user to authorize the CA certificate using out-
      of-band data (not an autonomic solution because the human user is
      involved),

   o  using a configured Explicit TA database (not an autonomic solution
      because the distribution of an explicit TA database is not
      autonomic),

   o  and using a Certificate-Less TLS mutual authentication method (not
      an autonomic solution because the distribution of symmetric key
      material is not autonomic).

   These "touch" methods do not meet the requirements for zero-touch.

   There are "call home" technologies where the Pledge first establishes
   a connection to a well known vendor service using a common client-
   server authentication model.  After mutual authentication appropriate
   credentials to authenticate the target domain are transfered to the
   Pledge.  This creates serveral problems and limitations:

   o  the pledge requires realtime connectivity to the vendor service,

   o  the domain identity is exposed to the vendor service (this is a
      privacy concern),

   o  the vendor is responsible for making the authorization decisions
      (this is a liability concern),

   BRSKI addresses these issues by defining extensions to the EST
   protocol for the automated distribution of vouchers.

1.2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].

   The following terms are defined for clarity:

   DomainID:  The domain identity is the 160-bit SHA-1 hash of the BIT
      STRING of the subjectPublicKey of the domain trust anchor that is
      stored by the Domain CA.  This is consistent with the
      Certification Authority subject key identifier (Section 4.2.1.2
      [RFC5280]) of the Domain CA's self signed root certificate.  (A
      string value bound to the Domain CA's self signed root certificate
      subject and issuer fields is often colloquially used as a
      humanized identity value but during protocol discussions the more
      exact term as defined here is used).

   drop ship:  The physical distribution of equipment containing the
      "factory default" configuration to a final destination.  In zero-
      touch scenarios there is no staging or pre-configuration during
      drop-ship.

   imprint:  The process where a device obtains the cryptographic key
      material to identify and trust future interactions with a network.
      This term is taken from Konrad Lorenz's work in biology with new
      ducklings: during a critical period, the duckling would assume
      that anything that looks like a mother duck is in fact their
      mother.  An equivalent for a device is to obtain the fingerprint
      of the network's root certification authority certificate.  A
      device that imprints on an attacker suffers a similar fate to a
      duckling that imprints on a hungry wolf.  Securely imprinting is a
      primary focus of this document.[imprinting].  The analogy to
      Lorenz's work was first noted in [Stajano99theresurrecting].

   enrollment:  The process where a device presents key material to a
      network and acquires a network specific identity.  For example
      when a certificate signing request is presented to a certification
      authority and a certificate is obtained in response.

   Pledge:  The prospective device, which has an identity installed by a
      third-party (e.g., vendor, manufacturer or integrator).

   Voucher  A signed statement from the MASA service that indicates to a
      Pledge the cryptographic identity of the Registrar it should
      trust.  There are different types of vouchers depending on how
      that trust asserted.  Multiple voucher types are defined in
      [I-D.ietf-anima-voucher]

   Domain:  The set of entities that trust a common key infrastructure
      trust anchor.  This includes the Proxy, Registrar, Domain
      Certificate Authority, Management components and any existing
      entity that is already a member of the domain.

   Domain CA:  The domain Certification Authority (CA) provides
      certification functionalities to the domain.  At a minimum it
      provides certification functionalities to a Registrar and stores
      the trust anchor that defines the domain.  Optionally, it
      certifies all elements.

   Join Registrar (and Coordinator):  A representative of the domain
      that is configured, perhaps autonomically, to decide whether a new
      device is allowed to join the domain.  The administrator of the
      domain interfaces with a Join Registrar (and Coordinator) to
      control this process.  Typically a Join Registrar is "inside" its
      domain.  For simplicity this document often refers to this as just
      "Registrar".  The term JRC is used in common with other bootstrap
      mechanisms.

   Join Proxy:  A domain entity that helps the pledge join the domain.
      A Proxy facilitates communication for devices that find themselves
      in an environment where they are not provided connectivity until
      after they are validated as members of the domain.  The pledge is
      unaware that they are communicating with a proxy rather than
      directly with a Registrar.

   MASA Service:  A third-party Manufacturer Authorized Signing
      Authority (MASA) service on the global Internet.  The MASA signs
      vouchers.  It also provides a repository for audit log information
      of privacy protected bootstrapping events.  It does not track
      ownership.

   Ownership Tracker:  An Ownership Tracker service on the global
      internet.  The Ownership Tracker uses business processes to
      accurately track ownership of all devices shipped against domains
      that have purchased them.  Although optional this component allows
      vendors to provide additional value in cases where their sales and
      distribution channels allow for accurately tracking of such
      ownership.  Ownership tracking information is indicated in
      vouchers as described in [I-D.ietf-anima-voucher]

   IDevID:  An Initial Device Identity X.509 certificate installed by
      the vendor on new equipment.

   TOFU:  Trust on First Use. Used similarly to [RFC7435].  This is
      where a Pledge device makes no security decisions but rather
      simply trusts the first Registrar it is contacted by.  This is
      also known as the "resurrecting duckling" model.

1.3.  Scope of solution

   Questions have been posed as to whether this solution is suitable in
   general for Internet of Things (IoT) networks.  This depends on the
   capabilities of the devices in question.  The terminology of
   [RFC7228] is best used to describe the boundaries.

   The solution described in this document is aimed in general at non-
   constrained (i.e. class 2+) devices operating on a non-Challenged
   network.  The entire solution as described here is not intended to be
   useable as-is by constrained devices operating on challenged networks
   (such as 802.15.4 LLNs).

   In many target applications, the systems involved are large router
   platforms with multi-gigabit inter-connections, mounted in controlled
   access data centers.  But this solution is not exclusive to the
   large, it is intended to scale to thousands of devices located in
   hostile environments, such as ISP provided CPE devices which are
   drop-shipped to the end user.  The situation where an order is
   fulfilled from distributed warehouse from a common stock and shipped
   directly to the target location at the request of the domain owner is
   explicitly supported.  That stock ("SKU") could be provided to a
   number of potential domain owners, and the eventual domain owner will
   not know a-priori which device will go to which location.

   The bootstrapping process can take minutes to complete depending on
   the network infrastructure and device processing speed.  The network
   communication itself is not optimized for speed; for privacy reasons,
   the discovery process allows for the Pledge to avoid announcing it's
   presence through broadcasting.

   This protocol is not intended for low latency handoffs.  In networks
   requiring such things, the pledge SHOULD already have been enrolled.

   Specifically, there are protocol aspects described here which might
   result in congestion collapse or energy-exhaustion of intermediate
   battery powered routers in an LLN.  Those types of networks SHOULD
   NOT use this solution.  These limitations are predominately related
   to the large credential and key sizes required for device
   authentication.  Defining symmetric key techniques that meet the
   operational requirements is out-of-scope but the underlying protocol
   operations (TLS handshake and signing structures) have sufficient
   algorithm agility to support such techniques when defined.

   The imprint protocol described here could, however, be used by non-
   energy constrained devices joining a non-constrained network (for
   instance, smart light bulbs are usually mains powered, and speak
   802.11).  It could also be used by non-constrained devices across a
   non-energy constrained, but challenged network (such as 802.15.4).
   The certificate contents, and the process by which the four questions
   above are resolved do apply to constrained devices.  It is simply the
   actual on-the-wire imprint protocol which could be inappropriate.

   This document presumes that network access control has either already
   occurred, is not required, or is integrated by the proxy and
   registrar in such a way that the device itself does not need to be
   aware of the details.  Although the use of an X.509 Initial Device
   Identity is consistant with IEEE 802.1AR [IDevID], and allows for
   alignment with 802.1X network access control methods, its use here is
   for Pledge authentication rather than network access control.
   Integrating this protocol with network access control, perhaps as an
   Extensible Authentication Protocol (EAP) method (see [RFC3748]), is
   out-of-scope.

1.4.  Leveraging the new key infrastructure / next steps

   As a result of the protocol described herein the bootstrapped devices
   have a common trust anchor and a certificate has optionally been
   issued from a local PKI.  This makes it possible to automatically
   deploy services across the domain in a secure manner.

   Services which benefit from this:

   o  Device management.

   o  Routing authentication.

   o  Service discovery.

   The major beneficiary is that it possible to use the credentials
   deployed by this protocol to secure the Autonomic Control Plane (ACP)
   ([I-D.ietf-anima-autonomic-control-plane]).

2.  Architectural Overview

   The logical elements of the bootstrapping framework are described in
   this section.  Figure 1 provides a simplified overview of the
   components.  Each component is logical and may be combined with other
   components as necessary.

                                             .
                                             .+------------------------+

                                              +------------------------+
      +--------------Drop Ship-------------->.| Ship--------------->| Vendor Service         |
      |                                      .+------------------------+                                       +------------------------+
      |                                       |                                      .| M anufacturer|         |
      |                                      .|                                       | A uthorized  |Ownership|
      |                                      .|                                       | S igning     |Tracker  |
      |                                      .|                                       | A uthority   |         |
      |                                      .+--------------+---------+                                       +--------------+---------+
      |                                      ..............                                                      ^
      |                                                      |  BRSKI-
      V                                                      |   MASA
   +-------+     ............................................|...
   |       |     .                                           |  .
   |       |     .  +------------+       +-----------+       |  .
   |       |     .  |            |       |           |       |  .
   |Pledge |     .  |   Circuit  |       | Domain    <-------+  .
   |       |     .  |   Proxy    |       | Registrar |          .
   |       <-------->            <------->       <-------->............<-------> (PKI RA)  |          .
   |       |     .  |        |        BRSKI-EST   |           |          .
   |X.509
   |       |     .  +------------+  |            |       +-----+-----+          .
   |IDevID |     .  +------------+             | EST RFC7030    .
   |       |     .           +-----------------+----------+     .
   |       |     .           | Key Infrastructure         |     .
   |       |     .           | (e.g. PKI Certificate      |     .
   +-------+     .           |       Authority)           |     .
                 .           +----------------------------+     .
                 .                                              .
                 ................................................
                               "Domain" components

   Figure 1

   We assume a multi-vendor network.  In such an environment there could
   be a Vendor Service for each vendor that supports devices following
   this document's specification, or an integrator could provide a
   generic service authorized by multiple vendors.  It is unlikely that
   an integrator could provide Ownership Tracking services for multiple
   vendors due to the required sales channel integrations necessary to
   track ownership.

   The domain is the managed network infrastructure with a Key
   Infrastructure the Pledge is joining.  The a domain provides initial
   device connectivity sufficient for bootstrapping with a Circuit
   Proxy.  The Domain registrar Registrar authenticates the Pledge, makes
   authorization decisions, and distributes vouchers obtained from the
   Vendor Service.  Optionally the Registrar also acts as a PKI
   Registration Authority.

2.1.  Secure Imprinting using Vouchers

   A voucher is a cryptographically protected statement to the Pledge
   device authorizing a zero-touch imprint on the Registrar domain.

   The format and cryptographic mechanism  Behavior of vouchers is described in
   detail in [I-D.ietf-anima-voucher].

   Vouchers provide a flexible mechanism to secure imprinting: the Pledge device only imprints when

   The pledge goes through a voucher can be validated.  At the
   lowest security levels the MASA server can indiscriminately issue
   vouchers.  At the highest security levels issuance series of vouchers can be
   integrated with complex sales channel integrations that steps which are beyond
   the scope of this document.  This provides the flexibility for outlined here at
   a
   number of use cases via high level.

                +--------------+
                |   Factory    |
                |   default    |
                +------+-------+
                       |
                +------v-------+
                |  Discover    |
   +------------>              |
   |            +------+-------+
   |                   |
   |            +------v-------+
   |            |  Identity    |
   ^------------+              |
   | rejected   +------+-------+
   |                   |
   |            +------v-------+
   |            | Request      |
   |            | Join         |
   |            +------+-------+
   |                   |
   |            +------v-------+
   |            |  Imprint     |   Optional
   ^------------+              <--+Manual input (Appendix C)
   | Bad Vendor +------+-------+
   | response          |  send Voucher Status Telemetry
   |            +------v-------+
   |            |  Enroll      |
   ^------------+              |
   | Enroll     +------+-------+
   | Failure           |
   |            +------v-------+
   |            |  Enrolled    |
   ^------------+              |
    Factory     +--------------+
    reset

   Figure 2

   State descriptions for the pledge are as follows:

   1.  Discover a single common protocol mechanism on communication channel to a Registrar.

   2.  Identify itself.  This is done by presenting an X.509 IDevID
       credential to the
   Pledge and discovered Registrar devices that (via the Proxy) in a TLS
       handshake.  (The Registrar credentials are only provisionally
       accepted at this time).

   3.  Requests to Join the discovered Registrar.  A unique nonce can be widely deployed in
       included ensuring that any responses can be associated with this
       particular bootstrapping attempt.

   4.  Imprint on the
   field.  The MASA vendor services have Registrar.  This requires verification of the flexibility to leverage
   either
       vendor service provided voucher.  A voucher contains sufficient
       information for the currently defined claim mechanisms or Pledge to experiment with
   higher or lower security levels.

   Vouchers provide complete authentication of a signed but non-encrypted communication channel
   between the Pledge,
       Registrar.  (It enables the MASA, and Pledge to finish authentication of
       the Registrar.  The Registrar
   maintains control over the transport and TLS server certificate).

   5.  Enroll.  By accepting the domain specific information from a
       Registrar, and by obtaining a domain certificate from a Registrar
       using a standard enrollment protocol, e.g.  Enrollment over
       Secure Transport (EST) [RFC7030].

   6.  The Pledge is now a member of, and can be managed by, the domain
       and will only repeat the discovery aspects of bootstrapping if it
       is returned to factory default settings.

2.2.  Secure Imprinting using Vouchers

   A voucher is a cryptographically protected statement to the Pledge
   device authorizing a zero-touch imprint on the Registrar domain.

   The format and cryptographic mechanism of vouchers is described in
   detail in [I-D.ietf-anima-voucher].

   Vouchers provide a flexible mechanism to secure imprinting: the
   Pledge device only imprints when a voucher can be validated.  At the
   lowest security levels the MASA server can indiscriminately issue
   vouchers.  At the highest security levels issuance of vouchers can be
   integrated with complex sales channel integrations that are beyond
   the scope of this document.  This provides the flexibility for a
   number of use cases via a single common protocol mechanism on the
   Pledge and Registrar devices that are to be widely deployed in the
   field.  The MASA vendor services have the flexibility to leverage
   either the currently defined claim mechanisms or to experiment with
   higher or lower security levels.

   Vouchers provide a signed but non-encrypted communication channel
   between the Pledge, the MASA, and the Registrar.  The Registrar
   maintains control over the transport and policy decisions allowing
   the local security policy of the domain network to be enforced.

2.2.

2.3.  Initial Device Identifier

   Pledge authentication and voucher request signing is via an X.509
   certificate installed during the manufacturing process.  This Initial
   Device Identifier provides a basis for authenticating the Pledge
   during subsequent protocol exchanges and informing the Registrar of
   the MASA URI.  There is no requirement for a common root PKI
   hierarchy.  Each device vendor can generate their own root
   certificate.

   The following previously defined fields are in the X.509 IDevID
   certificate:

   o  The subject field's DN encoding MUST include the "serialNumber"
      attribute with the device's unique serial number.

   o  The subject-alt field's encoding SHOULD include a non-critical
      version of the RFC4108 defined HardwareModuleName.

   In order to build the voucher "serial-number" field these IDevID
   fields need to be converted into a serial-number of "type string".
   The following methods is used depending on the first available IDevID
   certificate field (attempted in this order):

   o  An RFC4514 String Representation of the Distinguished Name
      "serialNumber" attribute.

   o  The HardwareModuleName hwSerialNum OCTET STRING base64 encoded.

   o  The RFC4514 String Representation of the Distinguished Name
      "common name" attribute.

   The following newly defined field SHOULD be in the X.509 IDevID
   certificate: An X.509 non-critical certificate extension that
   contains a single Uniform Resource Identifier (URI) that points to an
   on-line Manufacturer Authorized Signing Authority.  The URI is
   represented as described in Section 7.4 of [RFC5280].

   Any Internationalized Resource Identifiers (IRIs) MUST be mapped to
   URIs as specified in Section 3.1 of [RFC3987] before they are placed
   in the certificate extension.  The URI provides the authority
   information.  The BRSKI .well-known tree is described in Section 3 5

   The new extension is identified as follows:

   <CODE BEGINS>

   MASAURLExtnModule-2016 { iso(1) identified-organization(3) dod(6)
   internet(1) security(5) mechanisms(5) pkix(7)
   id-mod(0) id-mod-MASAURLExtn2016(TBD) }

   DEFINITIONS IMPLICIT TAGS ::= BEGIN

   -- EXPORTS ALL --

   IMPORTS
   EXTENSION
   FROM PKIX-CommonTypes-2009
   { iso(1) identified-organization(3) dod(6) internet(1)
   security(5) mechanisms(5) pkix(7) id-mod(0)
   id-mod-pkixCommon-02(57) }

   id-pe
   FROM PKIX1Explicit-2009
   { iso(1) identified-organization(3) dod(6) internet(1)
   security(5) mechanisms(5) pkix(7) id-mod(0)
   id-mod-pkix1-explicit-02(51) } ;
   MASACertExtensions EXTENSION ::= { ext-MASAURL, ... }
   ext-MASAURL EXTENSION ::= { SYNTAX MASAURLSyntax
   IDENTIFIED BY id-pe-masa-url }

   id-pe-masa-url OBJECT IDENTIFIER ::= { id-pe TBD }

   MASAURLSyntax ::= IA5String

   END

   <CODE ENDS>

   The choice of id-pe is based on guidance found in Section 4.2.2 of
   [RFC5280], "These extensions may be used to direct applications to
   on-line information about the issuer or the subject".  The MASA URL
   is precisely that: online information about the particular subject.

2.3.

2.4.  Protocol Flow

   A representative flow is shown in Figure 2: 3:

   +--------+         +---------+    +------------+     +------------+
   | Pledge |         | Circuit |    | Domain     |     | Vendor     |
   |        |         | Proxy   |    | Registrar  |     | Service    |
   |        |         |         |    |  (JRC)     |     | (Internet (MASA)     |
   +--------+         +---------+    +------------+     +------------+
     |                     |                   |           Internet |
     |<-RFC4862 IPv6 addr  |                   |                    |
     |<-RFC3927 IPv4 adr addr  | Appendix A        |                    |
   or|<-RFC4862 IPv6 adr   |                   |                    |
     |                     |                   |                    |
     |-------------------->|                   |                    |
     | optional: mDNS query| Appendix B        |                    |
     | RFC6763/RFC6762     |                   |                    |
     |                     |                   |                    |
     |<--------------------|                   |                    |
     | GRASP M_FLOOD       |                   |                    |
     |   periodic broadcast|                   |                    |
     |                     |                   |                    |
     |<------------------->C<----------------->|                    |
     |              TLS via the Circuit Proxy  |                    |
     |<--Registrar TLS server authentication---|                    |
   [PROVISIONAL accept of server cert]         |                    |
     P---X.509 client authentication---------->|                    |
     P                     |                   |                    |
     P---Request Voucher
     P---Voucher Request (include nonce)------>|                    |
     P                     |                   |                    |
     P                     |       /--->       |                    |
     P                     |       |      [accept device?]          |
     P                     |       |      [contact Vendor]          |
     P                     |       |           |--Pledge ID-------->|
     P                     |       |           |--Domain ID-------->|
     P                     |       |           |--optional:nonce--->|
     P                     |       |           |     [extract DomainID]
     P                     |       |           |                    |
     P                     |    optional:      |     [update audit log]
     P                     |       |can        |                    |
     P                     |       |occur      |                    |
     P                     |       |in         |                    |
     P                     |       |advance    |                    |
     P                     |       |       |if         |                    |
     P                     |       |nonceless  |                    |           |<-device audit log--|
     P                     |       |           |<- voucher ---------|
     P                     |       \---->      |                    |
     P                     |                   |                    |
     P                     |       [verify audit log and voucher]   |
     P                     |                   |                    |
     P<------voucher---------------------------|                    |
   [verify voucher ]       |                   |                    |
   [verify provisional cert|                   |                    |
     |                     |                   |                    |
     |---------------------------------------->|                    |
     |      [voucher status telemetry]         |<-device audit log--|
     |                     |       [verify audit log and voucher]   |
     |                     |                   |                    |
     |<--------------------------------------->|                    |
     | Continue with RFC7030 enrollment        |                    |
     | using now bidirectionally authenticated |                    |
     | TLS session.        |                   |                    |
     |                     |                   |                    |
     |                     |                   |                    |
     |                     |                   |                    |

   Figure 2

2.4. 3

2.4.1.  Architectural component: Pledge

   The Pledge is the device which is attempting to join.  Until the
   pledge completes the enrollment process, it does has network
   connectivity only to the Proxy.

2.4.2.  Architectural component: Circuit Proxy

   The (Circuit) Proxy provides HTTPS connectivity between the pledge
   and the registrar.  The proxy mechanism is described in Section 4,
   with an optional stateless mechanism described in Appendix C.

2.4.3.  Architectural component: Domain Registrar

   The Domain Registrar (having the formal name Join Registrar/
   Coordinator (JRC)), operates as a CMC Registrar, terminating the EST
   and BRSKI connections.  The Registrar is manually configured or
   distributed with a list of trust anchors necessary to authenticate
   any Pledge device expected on the network.  The Registrar
   communicates with the Vendor supplied MASA to establish ownership.

2.4.4.  Architectural component: Vendor Service

   The Vendor Service provides two logically seperate functions: the
   Manufacturer Authorized Signing Authority (MASA), and an ownership
   tracking/auditing function.

2.5.  Lack of realtime clock

   Many devices when bootstrapping do not have knowledge of the current
   time.  Mechanisms like Network Time Protocols can not be secured
   until bootstrapping is complete.  Therefore bootstrapping is defined
   in a method that does not require knowledge of the current time.

   Unfortunately there are moments during bootstrapping when
   certificates are verified, such as during the TLS handshake, where
   validity periods are confirmed.  This paradoxical "catch-22" is
   resolved by the Pledge maintaining a concept of the current "window"
   of presumed time validity that is continually refined throughout the
   bootstrapping process as follows:

   o  Initially the Pledge does not know the current time.

   o  During Pledge authentiation by the Registrar a realtime clock can
      be used by the Registrar.  This bullet expands on a closely
      related issue regarding Pledge lifetimes.  RFC5280 indicates that
      long lived Pledge certifiates "SHOULD be assigned the
      GeneralizedTime value of 99991231235959Z" [RFC7030] so the
      Registrar MUST support such lifetimes and SHOULD support ignoring
      Pledge lifetimes if they did not follow the RFC5280
      recommendations.

   o  The Pledge authenticates the voucher presented to it.  During this
      authentication the Pledge ignores certificate lifetimes (by
      necessity because it does not have a realtime clock).

   o  If the voucher contains a nonce then the Pledge MUST confirm the
      nonce matches the original voucher request.  This ensures the
      voucher is fresh.  See / (Section 3.2). 5.2).

   o  Once the voucher is accepted the validity period of the
      domainCAcert pinned-
      domain-cert in the voucher (see Section 3.4) now serves as a valid time window.  Any
      subsequent certificate validity periods checked during RFC5280
      path validation MUST occur within this window.

   o  When accepting an enrollment certificate the validity period
      within the new certificate is assumed to be valid by the Pledge.
      The Pledge is now willing to use this credential for client
      authentication.

2.5.

2.6.  Cloud Registrar

   The Pledge MAY contact a well known URI of a cloud Registrar if a
   local Registrar can not be discovered or if the Pledge's target use
   cases do not include a local Registrar.

   If the Pledge uses a well known URI for contacting a cloud Registrar
   an Implicit Trust Anchor database (see [RFC7030]) MUST be used to
   authenticate service as described in RFC6125.  This is consistent
   with the human user configuration of an EST server URI in [RFC7030]
   which also depends on RFC6125.

3.  Protocol Details

2.7.  Determining the MASA to contact

   The Pledge MUST initiate BRSKI after boot if it registrar needs to be able to contact a MASA that is unconfigured.  The trusted by
   the Pledge MUST NOT automatically initiate BRSKI if it has been
   configured or is in the process of being configured.

   BRSKI is described as extensions to EST [RFC7030] order to reduce obtain vouchers.  There are three mechanisms
   described:

   The device's Initial Device Identifier will normally contain the
   number of TLS connections and crypto operations required on MASA
   URL as detailed in Section 2.3.  This is the RECOMMENDED mechanism.

   If the
   Pledge.  The Registrar implements is integrated with [I-D.ietf-opsawg-mud] and the BRSKI REST interface within
   Pledge IDevID contains the
   same .well-known URI tree as id-pe-mud-url then the Registrar MAY
   attempt to obtain the existing EST URIs as described in
   EST [RFC7030] section 3.2.2.  A MASA URI is therefore "https://
   authority "./well-known/est".

   Establishment of URL from the TLS connection MUD file.  The MUD file
   extension for bootstrapping the MASA URL is as specified defined in EST [RFC7030] section 4.1.1 "Bootstrap Distribution of CA
   Certificates" [RFC7030] with Appendix D.

   It can be operationally difficult to ensure the following extensions for automation:

   Automation necessary X.509
   extensions for are in the Pledge (equivalent Pledge's' IDevID due to EST client) are:

   o  The Pledge provisionally accepts the Registrar certificate during the TLS handshake as detailed in EST.

   o  If difficulty of
   aligning current Pledge manufacturing with software releases and
   development.  As a final fallback the Registrar responds MAY be manually
   configured or distributed with a redirection to other web origins MASA URL for each vendor.  Note that
   the Pledge MUST follow Registrar can only select the configured MASA URL based on the
   trust anchor -- so vendors can only leverage this approach if they
   ensure a single redirection.  (EST supports
      redirection but does not allow redirections to other web origins
      without user input).

   o  The Registar MAY respond MASA URL works for all Pledge's associated with each
   trust anchor.

3.  Voucher Request artifact

   The voucher request is how an HTTP 202 ("the entity requests a voucher.  The Pledge
   forms a voucher request has been
      accepted for processing, but and submits it to the processing has not been
      completed") as described Registrar.  The
   Registrar in EST [RFC7030] section 4.2.3 wherein
      the client "MUST wait at least the specified 'retry-after' time
      before repeating turn submits a voucher request to the same request".  The Pledge MASA server.  A
   voucher request is RECOMMENDED to
      provide local feed (blinked LED etc) during this wait cycle if
      mechanisms for this are available.  To prevent a voucher structure with an attacker
      Registrar from significantly delaying bootstrapping the Pledge
      MUST limit the 'retry-after' time additional "prior-
   signed-voucher-request" "leaf to 60 seconds.  To avoid waiting
      on a single erroneous Registrar the Pledge MUST drop support forwarding the
      connection after 5 seconds and proceed to other discovered
      Registrars.  Ideally Pledge's
   initial voucher request.

   Unless otherwise signaled (outside the Pledge could keep track of voucher artifact), the
      appropriate retry-after value signing
   structure is as defined for any number vouchers, see [I-D.ietf-anima-voucher].

3.1.  Tree Diagram

   The following tree diagram illustrates a high-level view of outstanding
      Registrars but this would involve a large state table on the
      Pledge.  Instead voucher
   request document.  The notation used in this diagram is described in
   [I-D.ietf-anima-voucher].  Each node in the Pledge MAY ignore diagram is fully
   described by the exact retry-after value YANG module in favor of a single hard coded value that takes effect between
      discovery (Appendix D.1.1.1) attempts.  A Registrar that is unable
      to complete Section 3.3.  Please review the transaction YANG
   module for a detailed description of the first time due voucher request format.

   module: ietf-voucher-request
     groupings:
     voucher-request-grouping
         +---- voucher
            +---- created-on?                      yang:date-and-time
            +---- expires-on?                      yang:date-and-time
            +---- assertion                        enumeration
            +---- serial-number                    string
            +---- idevid-issuer?                   binary
            +---- pinned-domain-cert?              binary
            +---- domain-cert-revocation-checks?   boolean
            +---- nonce?                           binary
            +---- last-renewal-date?               yang:date-and-time
            +---- prior-signed-voucher-request?    binary
            +---- proximity-registrar-cert?        binary

3.2.  Examples

   This section provides voucher examples for illustration purposes.
   That these examples conform to timing reasons
      will have future chances.

   o the encoding rules defined in
   [RFC7951].

   Example (1)  The following example illustrates a Pledge requests generated
                voucher-request.  The assertion leaf is indicated as
                'proximity' and validates a voucher using the new REST
      calls described below.

   o  If necessary the Pledge calls Registrar's TLS server certificate
                is included in the EST defined /cacerts method to
      obtain the current CA certificate.  These are validated using the
      Voucher.

   o 'pinned-domain-cert' leaf.  See
                Section 5.2.

   {
       "ietf-voucher-request:voucher": {
           "nonce": "62a2e7693d82fcda2624de58fb6722e5",
           "created-on": "2017-01-01T00:00:00.000Z",
           "assertion": "proximity",
           "proximity-registrar-cert": "base64encodedvalue=="
       }
   }

   Example (2)  The Pledge completes authentication of following example illustrates a Registrar generated
                voucher-request.  The 'prior-signed-voucher-request'
                leaf is populated with the server certificate Pledge's voucher request
                (such as
      detailed in Section 3.4.1.  This moves the TLS connection out of
      the provisional state.  Optionally the TLS connection can now be
      used for EST enrollment. prior example).  See Section 5.4.

   {
       "ietf-voucher-request:voucher": {
           "nonce": "62a2e7693d82fcda2624de58fb6722e5",
           "created-on": "2017-01-01T00:00:02.000Z",
           "assertion": "proximity",
           "idevid-issuer": "base64encodedvalue=="
           "serial-number": "JADA123456789"
           "prior-signed-voucher": "base64encodedvalue=="
       }
   }

   Example (3)  The Pledge establishes the TLS connection with the following example illustrates a Registrar through
   the circuit proxy (see Appendix D.1.2) but the TLS connection generated
                voucher-request.  The 'prior-signed-voucher-request'
                leaf is not populated with the Registar; so in the above section the "Pledge" Pledge's voucher request
                nor is the TLS client
   and nonce leaf.  This form might be used by a
                Registrar requesting a voucher when the "Registrar" Pledge is the TLS server.  All security associations
   established are between the new device and
                offline or when the Registrar regardless
   of proxy operations. expects to be offline
                during deployment.  See Section 5.4.

   {
       "ietf-voucher-request:voucher": {
           "created-on": "2017-01-01T00:00:02.000Z",
           "assertion": "TBD",
           "idevid-issuer": "base64encodedvalue=="
           "serial-number": "JADA123456789"
       }
   }

   Example (4)  The extensions for following example illustrates a Registrar (equivalent to EST server) are:

   o  Client authentication is automated using Initial Device Identity. generated
                voucher-request.  The subject field's DN encoding MUST include the "serialNumber"
      attribute 'prior-signed-voucher-request'
                leaf is not populated with the device's unique serial number.  In Pledge's voucher request
                because the language
      of RFC6125 this provides for a SERIALNUM-ID category of identifier
      that can be included in a certificate and therefore that can also Pledge did not sign it's own request.  This
                form might be used for matching purposes. when more constrained Pledges are
                being deployed.  The SERIALNUM-ID whitelist nonce is
      collated according to vendor trust anchor since serial numbers are
      not globally unique.

   o  The Registrar requests and validates the Voucher populated from the vendor
      authorized MASA service.

   o  The Registrar forwards the Voucher to the Pledge when requested.

   o  The Registar performs log verifications in addition to local
      authorization checks before accepting optional Pledge device
      enrollment requests.

3.1.  Discovery

   The result of discovery
                Pledge's request.  See Section 5.4.

   {
       "ietf-voucher-request:voucher": {
           "nonce": "62a2e7693d82fcda2624de58fb6722e5",
           "created-on": "2017-01-01T00:00:02.000Z",
           "assertion": "proximity",
           "idevid-issuer": "base64encodedvalue=="
           "serial-number": "JADA123456789"
       }
   }

3.3.  YANG Module

   Following is a logical communication with a Registrar,
   through a Proxy.  The Proxy is transparent to YANG [RFC7950] module formally extending the Pledge but
   [I-D.ietf-anima-voucher] voucher into the voucher request.

<CODE BEGINS> file "ietf-voucher-request@2017-10-13.yang"
module ietf-voucher-request {
  yang-version 1.1;

  namespace
    "urn:ietf:params:xml:ns:yang:ietf-voucher-request";
  prefix "vch";

  import ietf-restconf {
    prefix rc;
    description
      "This import statement is
   always assumed only present to exist.

   To discover the Registrar access
       the Pledge performs yang-data extension defined in RFC 8040.";
    reference "RFC 8040: RESTCONF Protocol";
  }

  import ietf-voucher {
    prefix v;
    description
      "FIXME";
    reference "RFC ????: Voucher Profile for Bootstrapping Protocols";
  }

  organization
   "IETF ANIMA Working Group";

  contact
   "WG Web:   <http://tools.ietf.org/wg/anima/>
    WG List:  <mailto:anima@ietf.org>
    Author:   Kent Watsen
              <mailto:kwatsen@juniper.net>
    Author:   Max Pritikin
              <mailto:pritikin@cisco.com>
    Author:   Michael Richardson
              <mailto:mcr+ietf@sandelman.ca>
    Author:   Toerless Eckert
              <mailto:tte+ietf@cs.fau.de>";

  description
   "This module... FIXME

    The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT',
    'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and 'OPTIONAL' in
    the following actions:

   a.  MUST: Obtains a local address using IPv6 methods module text are to be interpreted as described in
       [RFC4862] IPv6 Stateless Address AutoConfiguration.  [RFC7217] is
       encouraged.  Pledges will generally prefer use of IPv6 Link-Local
       addresses, RFC 2119.

    Copyright (c) 2017 IETF Trust and discovery the persons identified as
    authors of Proxy will be by Link-Local
       mechanisms.  IPv4 methods are described the code. All rights reserved.

    Redistribution and use in Appendix A

   b.  MUST: Listen for GRASP M_FLOOD ([I-D.ietf-anima-grasp])
       announcements of source and binary forms, with or without
    modification, is permitted pursuant to, and subject to the objective: "ACP+Proxy".  See section
       Section 3.1.1 for license
    terms contained in, the details Simplified BSD License set forth in Section
    4.c of the IETF Trust's Legal Provisions Relating to IETF Documents
    (http://trustee.ietf.org/license-info).

    This version of this YANG module is part of RFC XXXX; see the objective.  The Pledge
       may listen concurrently RFC
    itself for other sources of information, see
       Appendix B.

   Once a proxy is discovered the Pledge communicates with a Registrar
   through the proxy using the bootstrapping protocol full legal notices.";

  revision "2017-10-13" {
    description
     "Initial version";
    reference
     "RFC XXXX: Voucher Profile for Bootstrapping Protocols";
  }

  // Top-level statement
  rc:yang-data voucher-request-artifact {
    uses voucher-request-grouping;
  }

  // Grouping defined for future usage
  grouping voucher-request-grouping {
    description
      "Grouping to allow reuse/extensions in
   Section 3.

   Each discovery method attempted SHOULD exponentially back-off
   attempts (to a maximum of one hour) future work.";

    uses v:voucher-artifact-grouping {
      refine "voucher/created-on" {
        mandatory false;
      }

      refine "voucher/pinned-domain-cert" {
        mandatory false;
      }

      augment "voucher"  {
        description
          "Adds leaf nodes appropriate for requesting vouchers.";

        leaf prior-signed-voucher-request {
          type binary;
          description
            "If it is necessary to avoid overloading change a voucher, or re-sign and
             forward a voucher that was previously provided along a
             protocol path, then the network
   infrastructure with discovery.  The back-off timer for each method
   MUST be independent of other methods.

   Methods previously signed voucher SHOULD be run
             included in parallel to avoid head of queue problems
   wherein an attacker running this field.

             For example, a fake proxy or registrar can operate
   protocol actions intentionally slowly.

   Once pledge might sign a connection proximity voucher, which
             an intermediate registrar then re-signs to a Registrar make its own
             proximity assertion.  This is established (e.g. establishment
   of a TLS session key) there are expectations simple mechanism for a
             chain of more timely
   responses, see Section 3.2.

   Once all discovered services are attempted the device SHOULD return trusted parties to listening for GRASP M_FLOOD.  It should periodically retry change a voucher, while
             maintaining the
   vendor specific mechanisms. prior signature information.

             The Pledge MAY prioritize selection
   order as appropriate pledge MUST ignore all prior voucher information when
             accepting a voucher for imprinting. Other parties MAY
             examine the anticipated environment.

3.1.1.  Proxy Discovery Protocol Details

   The proxy uses prior signed voucher information for the GRASP M_FLOOD mechanism to announce itself.  This
   announcement is done with
             purposes of policy decisions. For example this information
             could be useful to a MASA to determine that both pledge and
             registrar agree on proximity assertions. The MASA SHOULD
             remove all prior-signed-voucher information when signing
             a voucher for imprinting so as to minimize the same message final
             voucher size.";
        }

        leaf proximity-registrar-cert {
          type binary;
          description
            "An X.509 v3 certificate structure as specified by RFC 5280,
             Section 4 encoded using the ACP announcement
   detailed ASN.1 distinguished encoding
             rules (DER), as specified in ITU-T X.690.

             The first certificate in [I-D.ietf-anima-autonomic-control-plane].

    proxy-objective = ["Proxy", [ O_IPv6_LOCATOR, ipv6-address,
    transport-proto, port-number ] ]

    ipv6-address       - the v6 LL of the proxy
    transport-proto    - 6, for TCP 17 for UDP
    port-number        - the TCP or UDP port number to find the proxy

   Figure 5

3.1.2.  Registrar Discovery Protocol Details

   A Registrar is typically configured manually.  When TLS server
             certificate_list sequence  (see [RFC5246]) presented by
             the Registrar
   joins an Autonomic Control Plane
   ([I-D.ietf-anima-autonomic-control-plane]) it MUST respond to GRASP
   ([I-D.ietf-anima-grasp]) M_NEG_SYN message.

   The registrar responds to discovery messages from the proxy (or GRASP
   caches between them) as follows: (XXX changed from M_DISCOVERY)

    objective         = ["AN_registrar", F_DISC, 255 ]
    discovery-message = [M_NEG_SYN, session-id, initiator, objective]

   Figure 6: Registrar Discovery

   The response from the registrar (or cache) will Pledge. This MUST be populated in a M_RESPONSE with
             Pledge's voucher request if the following parameters:

    response-message = [M_RESPONSE, session-id, initiator, ttl,
    (+locator-option // divert-option), ?objective)]
    initiator = ACP address of Registrar
    locator1  = [O_IPv6_LOCATOR, fd45:1345::6789, 6,  443]
    locator2  = [O_IPv6_LOCATOR, fd45:1345::6789, 17, 5683]
    locator3  = [O_IPv6_LOCATOR, fe80::1234, 41, nil]

   Figure 7: Registrar Response proximity assertion is
             populated.";
        }
      }
    }
  }

}

<CODE ENDS>

4.  Proxy details

   The set role of locators the Proxy is to be interpreted as follows.  A protocol of 6
   indicates that TCP proxying on facilitate communications.  The Proxy
   forwards packets between the indicated port is desired.  A
   protocol of 17 indicates Pledge and a Registrar that UDP proxying has been
   configured on the indicated port Proxy.

   The Proxy does not terminate the TLS handshake: it passes streams of
   bytes onward without examination.

   A proxy MAY assume TLS framing for auditing purposes, but MUST NOT
   assume any TLS version.

   A Proxy is
   desired.  In each case, always assumed even if it is directly integrated into a
   Registrar.  (In a completely autonomic network, the traffic SHOULD Registrar MUST
   provide proxy functionality so that it can be proxied to discovered, and the same
   port at
   network can grow concentrically around the ULA address provided.

   A protocol Registrar)

   As a result of 41 indicates that packets may the Proxy Discovery process in section Section 4.1.1,
   the port number exposed by the proxy does not need to be IPIP proxy'ed.  In well known,
   or require an IANA allocation.

   If the
   case of that IPIP proxying is used, then Proxy joins an Autonomic Control Plane
   ([I-D.ietf-anima-autonomic-control-plane]) it SHOULD use Autonomic
   Control Plane secured GRASP ([I-D.ietf-anima-grasp]) to discovery the provided link-local
   Registrar address MUST be advertised on and port.  As part of the discovery process, the local link using
   proxy neighbour
   discovery.  The Join mechanism (Circuit Proxy MAY limit forwarded traffic vs IPIP encapsulation) is agreed to
   between the
   protocol (6 and 17) Registrar and Join Proxy.

   For the IPIP encapsulation methods (described in Appendix C), the
   port numbers indicated announced by locator1 and
   locator2.  The address to which the IPIP traffic should Proxy SHOULD be sent is
   the initiator address (an ACP address of the Registrar), not same as on the
   address given registrar in
   order for the locator.

   Registrars MUST accept TCP / UDP traffic on proxy to remain stateless.

   In order to permit the ports given at proxy functionality to be implemented on the
   ACP address
   maximum variety of devices the Registrar.  If the Registrar supports IPIP
   tunnelling, it MUST also accept traffic encapsulated with IPIP.

   Registrars MUST accept HTTPS/EST traffic on chosen mechanism SHOULD use the TCP ports indicated.
   Registrars MAY accept DTLS/CoAP/EST traffic
   minimum amount of state on the UDP proxy device.  While many devices in addition to
   TCP traffic.

3.2.  Request Voucher from
   the Registrar

   When ANIMA target space will be rather large routers, the Pledge bootstraps it makes proxy
   function is likely to be implemented in the control plane CPU of such
   a request device, with available capabilities for the proxy function similar
   to many class 2 IoT devices.

   The document [I-D.richardson-anima-state-for-joinrouter] provides a Voucher from a
   Registrar.

   This is done with an HTTPS POST using
   more extensive analysis and background of the operation path value alternative proxy
   methods.

4.1.  Pledge discovery of
   "/requestvoucher".

   The request media types are:

   application/voucherrequest Proxy

   The request result of discovery is a "YANG-defined JSON
      document that has been signed using logical communication with a PKCS#7 structure" as
      described in [I-D.ietf-anima-voucher] using the JSON encoded
      described in [RFC7951].  Signing the request Registrar,
   through a Proxy.  The Proxy is RECOMMENDED if transparent to the Pledge has sufficient processing but is
   always assumed to perform the crypto operations.
      Doing so allows exist.

   To discover the Registrar to forward Proxy the Pledge's signed
      'proximity' assertion to Pledge performs the MASA following actions:

   1.  MUST: Obtains a local address using IPv6 methods as discussed described in the security
      considerations.

   application/unsignedvoucherrequest  The request is the "YANG-defined
      JSON document" but has not been signed.  It
       [RFC4862] IPv6 Stateless Address AutoConfiguration.  Use of

       [RFC4941] temporary addresses is encouraged.  A new temporary
       address SHOULD be allocated whenever the inner JSON
      structure protected only by the TLS client authentication.  This
      reduces the cryptographic requirements on the Pledge.

   For simplicity the term 'voucher request' discovery process is used
       forced to refer restart due to either failures.  Pledges will generally prefer
       use of these media types.  Registrar impementations SHOULD anticipate
   future media types but IPv6 Link-Local addresses, and discovery of course Proxy will simply fail the request if
   those types are not yet known.

   The Pledge populates the voucher request fields as follows:

   created-on:  Pledges that have a realtime clock be
       by Link-Local mechanisms.  IPv4 methods are RECOMMENDED to
      populate this field.  This provides additional information to described in
       Appendix A

   2.  MUST: Listen for GRASP M_FLOOD ([I-D.ietf-anima-grasp])
       announcements of the
      MASA.

   nonce:  The voucher request MUST contain a cryptographically strong
      random or pseudo-random number nonce.  Doing so ensures objective: "AN_Proxy".  See section
       Section 2.4 functionality.  The nonce MUST NOT be reused 4.1.1 for
      multiple bootstrapping attempts.

   assertion: the details of the objective.  The voucher request MAY contain an assertion Pledge may
       listen concurrently for other sources of
      "proximity".

   pinned-domain-cert:  In information, see
       Appendix B.

   Once a Pledge voucher request this proxy is discovered the Pledge communicates with a Registrar certificate as extracted from
   through the TLS handshake (for
      example proxy using the first certificate bootstrapping protocol defined in
   Section 5.

   Each discovery method attempted SHOULD exponentially back-off
   attempts (to a maximum of one hour) to avoid overloading the TLS 'certificate_list'
      sequence (see [RFC5246]).  This network
   infrastructure with discovery.  The back-off timer for each method
   MUST be populated in a Pledge's
      voucher request if the "proximity" assertion is populated.

   All independent of other fields MAY methods.

   Methods SHOULD be ommitted run in the voucher request.

   An example JSON payload parallel to avoid head of queue problems
   wherein an attacker running a voucher request from fake proxy or registrar can operate
   protocol actions intentionally slowly.

   Once a connection to a Pledge:

   {
     "ietf-voucher:voucher": {
       "nonce": "62a2e7693d82fcda2624de58fb6722e5",
       "created-on": "2017-01-01T00:00:00.000Z",
       "assertion": "proximity",
       "pinned-domain-cert": "<base64 encoded certificate>"
     }
   }

   The Registrar validates the client identity as described in EST
   [RFC7030] section 3.3.2.  If the request is signed established (e.g. establishment
   of a TLS session key) there are expectations of more timely
   responses, see Section 5.2.

   Once all discovered services are attempted the Registrar
   confirms device SHOULD return
   to listening for GRASP M_FLOOD.  It should periodically retry the 'proximity' asserion and associated 'pinned-domain-cert'
   are correct.
   vendor specific mechanisms.  The registrar performs authorization Pledge MAY prioritize selection
   order as detailed in
   [[EDNOTE: UNRESOLVED.  See Appendix D "Pledge Authorization"]].  If
   these validations fail the Registrar SHOULD respond with an appropriate HTTP error code.

   If authorization is successful for the Registrar obtains a voucher from anticipated environment.

4.1.1.  Proxy Grasp announcements

   A proxy uses the MASA service (see Section 3.3) and returns that MASA signed
   voucher GRASP M_FLOOD mechanism to the announce itself.  The
   pledge as described in Section 3.4.

3.3.  Request Voucher from MASA

   when a Registrar recieves a voucher request from a Pledge it in turn
   requests a voucher from SHOULD listen for messages of these form.  This announcement
   can be within the MASA service.  For simplicity this is
   defined as an optional EST same message between a Registrar and an EST
   server running on the MASA service although as the Registrar is not
   required to make use ACP announcement detailed in
   [I-D.ietf-anima-autonomic-control-plane].

    proxy-objective = ["AN_Proxy", [ O_IPv6_LOCATOR, ipv6-address,
    transport-proto, port-number ] ]

    ipv6-address       - the v6 LL of any other EST functionality when
   communicating with the MASA service.  (The MASA service MUST properly
   reject any EST functionality requests it does not wish to service; a
   requirement that holds proxy
    transport-proto    - 6, for any REST interface).

   This is done with an HTTP POST using TCP 17 for UDP
    port-number        - the operation path value of
   "/requestvoucher".

   The request media type is:

   application/voucherrequest  The request is a "YANG-defined JSON
      document that has been signed using a PKCS#7 structure" as
      described in [I-D.ietf-anima-voucher] using TCP or UDP port number to find the JSON encoded
      described in [RFC7951].  The proxy

   Figure 5

4.2.  CoAP connection to Registrar MUST sign the request.

   The
      entire Registrar certificate chain, up use of CoAP to connect from Pledge to Registrar is out of scope
   for this document, and including the Domain
      CA, MUST may be included described in the PKCS#7 structure.

   For simplicity the term 'voucher request' is used.  MASA
   impementations SHOULD anticipate future media types but work.

4.3.  HTTPS proxy connection to Registrar

   The proxy SHOULD also provide one of: an IPIP encapsulation of course
   will simply fail HTTP
   traffic to the request if those types are not yet known.

   The Registrar populates registrar, or a TCP circuit proxy that connects the voucher request fields as follows:

   created-on:  Registrars are RECOMMENDED
   Pledge to populate this field.  This a Registrar.

   When the Proxy provides additional information a circuit proxy to a Registrar the MASA.

   nonce: Registrar
   MUST accept HTTPS connections.

4.4.  Proxy discovery of Registrar

   The optional nonce value from the Pledge request if desired
      (see below).

   serial-number:  The serial number Registrar SHOULD announce itself so that proxies can find it and
   determine what kind of connections can be terminated.

   When the Pledge Registrar joins an Autonomic Control Plane
   ([I-D.ietf-anima-autonomic-control-plane]) it MUST respond to GRASP
   ([I-D.ietf-anima-grasp]) M_NEG_SYN message.

   The registrar responds to discovery messages from the proxy (or GRASP
   caches between them) as follows: (XXX changed from M_DISCOVERY)

    objective         = ["AN_registrar", F_DISC, 255 ]
    discovery-message = [M_NEG_SYN, session-id, initiator, objective]

   Figure 6: Registrar would
      like a voucher for.

   idevid-issuer: Discovery

   The idevid-issuer value response from the pledge certificate
      is included to ensure registrar (or cache) will be a statistically unique identity. M_RESPONSE with
   the following parameters:

    response-message = [M_RESPONSE, session-id, initiator, ttl,
    (+locator-option // divert-option), ?objective)]
    initiator = ACP address of Registrar
    locator1  = [O_IPv6_LOCATOR, fd45:1345::6789, 6,  443]
    locator2  = [O_IPv6_LOCATOR, fd45:1345::6789, 17, 5683]
    locator3  = [O_IPv6_LOCATOR, fe80::1234, 41, nil]

   Figure 7: Registrar Response

   The
      Pledge's serial number set of locators is extracted from to be interpreted as follows.  A protocol of 6
   indicates that TCP proxying on the X.509 IDevID.  See
      Section 2.2.

   prior-signed-voucher:  If indicated port is desired.  A
   protocol of 17 indicates that UDP proxying on the Pledge provided a signed voucher
      request then it indicated port is
   desired.  In each case, the traffic SHOULD be included in proxied to the voucher request built by same
   port at the Registrar.

   All other fields MAY ULA address provided.

   A protocol of 41 indicates that packets may be ommitted in IPIP proxy'ed.  In the voucher request.

   An example JSON payload
   case of a voucher request from a Registrar:

   {
     "ietf-voucher:voucher": {
       "nonce": "62a2e7693d82fcda2624de58fb6722e5",
       "created-on": "2017-01-01T00:00:00.000Z",
       "assertion": "proximity"
       "idevid-issuer": "<base64 encoded Authority Key Identifier>"
       "serial-number": "JADA123456789"
       "prior-signed-voucher": "<base64 encode prior voucher request>"
     }
   }

   A Registrar MAY exclude that IPIP proxying is used, then the nonce from provided link-local
   address MUST be advertised on the voucher request it submits local link using proxy neighbour
   discovery.  The Join Proxy MAY limit forwarded traffic to the MASA.  Doing so allows the Registrar
   protocol (6 and 17) and port numbers indicated by locator1 and
   locator2.  The address to request a Voucher when which the Pledge IPIP traffic should be sent is offline, or when
   the Registrar is expected to be
   offline when initiator address (an ACP address of the Pledge is being deployed.  These use cases require Registrar), not the Registrar to learn
   address given in the appropriate IDevID SerialNumber field from locator.

   Registrars MUST accept TCP / UDP traffic on the physical device labeling or from ports given at the sales channel (out-of-scope
   ACP address of this document). the Registrar.  If a nonce is not provided the MASA server Registrar supports IPIP
   tunnelling, it MUST
   authenticate also accept traffic encapsulated with IPIP.

   Registrars MUST accept HTTPS/EST traffic on the Registrar as described TCP ports indicated.
   Registrars MAY accept DTLS/CoAP/EST traffic on the UDP in addition to
   TCP traffic.

5.  Protocol Details

   The Pledge MUST initiate BRSKI after boot if it is unconfigured.  The
   Pledge MUST NOT automatically initiate BRSKI if it has been
   configured or is in the process of being configured.

   BRSKI is described as extensions to EST [RFC7030] section
   3.3.2 to reduce the risk
   number of DDoS attacks and to provide an
   authenticated identity as an input to sales channel integration TLS connections and
   authorizations (also out-of-scope of this document).

   The MASA verifies that crypto operations required on the voucher request is internally consistent
   but does not authenticate
   Pledge.  The Registrar implements the domain identity information since BRSKI REST interface within the
   domain is not know to
   same .well-known URI tree as the MASA server in advance.  The MASA
   validation checks before issuing a voucher are existing EST URIs as follows:

   Renew for expired voucher:  As described in [I-D.ietf-anima-voucher]
      vouchers are normally short lived to avoid revocation issues.  If
   EST [RFC7030] section 3.2.2.  The communication channel between the request is for a previous (expired) voucher using
   Pledge and the same Registrar (as determined by is referred to as "BRSKI-EST" (see
   Figure 1).

   The communication channel between the Registrar pinned-domain-cert) and
      the MASA has not been informed that the claim is invalid then similarly
   described as extensions to EST within the
      request same ./well-known tree.

   For clarity this channel is referred to as "BRSKI-MASA".  (See
   Figure 1).

   MASA URI is "https:// authority "./well-known/est".

   BRSKI uses EST message formats for a renewed existing operations, uses JSON
   [RFC7159] for all new operations defined here, and voucher formats.

   While EST section 3.2 does not insist upon use of HTTP 1.1 persistent
   connections, BRSKI-EST connections SHOULD be automatically authorized.

   Voucher signature consistency: use persistent connections.
   The MASA MUST verify that the voucher
      request intention of this guidance is signed by a Registrar.  This to ensure the provisional TLS
   authentication occurs only once and is confirmed by verifying
      that properly managed.

   Summarized automation extensions for the id-kp-cmcRA extended key usage extension field (as
      detailed in EST RFC7030 section 3.6.1) exists in BRSKI-EST flow are:

   o  The Pledge provisionally accepts the Registrar certificate
      of during
      the entity that signed TLS handshake as detailed in Section 5.1.

   o  If the voucher request.  This verification
      is only Registrar responds with a consistency check that the unauthenticated domain CA
      intended this redirection to be a Registrar.  Performing this check provides
      value to domain PKI by assuring the domain administrator that other web origins
      the
      MASA service will Pledge MUST follow only respect claims from authorized Registration
      Authorities of the domain.  (The requirement for the Registrar a single redirection.  (EST supports
      redirection but does not allow redirections to
      include other web origins
      without user input).

   o  The Registar MAY respond with an HTTP 202 ("the request has been
      accepted for processing, but the Domain CA certificate processing has not been
      completed") as described in EST [RFC7030] section 4.2.3 wherein
      the signature structure was
      stated above).

   Registrar revocation consistency: client "MUST wait at least the specified 'retry-after' time
      before repeating the same request".  The MASA SHOULD check Pledge is RECOMMENDED to
      provide local feed (blinked LED etc) during this wait cycle if
      mechanisms for
      revocation of this are available.  To prevent an attacker
      Registrar from significantly delaying bootstrapping the Pledge
      MUST limit the 'retry-after' time to 60 seconds.  To avoid
      blocking on a single erroneous Registrar certificate.  The maximum lifetime of the voucher issued SHOULD NOT exceed Pledge MUST drop the lifetime of
      connection after 5 seconds in which there has been no progress on
      the
      Registrar's revocation validation (for example TCP connection.  It should proceed to other discovered
      Registrars if there are any.  If there were no other Registrars
      discovered, the Registrar
      revocation status is indicated in a CRL that is valid for two
      weeks then that pledge MAY continue to wait, as long as it is an appropriate lifetime
      concurrently listening for new proxy announcements.

   o  Ideally the voucher).
      Because the Registar certificate authority is unknown to Pledge could keep track of the MASA
      in advance this is only an extended consistency check and is not
      required.  The maximum lifetime appropriate retry-after
      value for any number of outstanding Registrars but this would
      involve a large state table on the voucher issued SHOULD NOT
      exceed the lifetime of Pledge.  Instead the Registrar's revocation validation (for
      example if pledge MAY
      ignore the Registrar revocation status is indicated exact retry-after value in favor of a CRL
      that is valid for two weeks then that is an appropriate lifetime
      for the voucher).

   Pledge proximity assertion:  The MASA server MAY verify single hard coded
      value that the takes effect between discovery ([[ProxyDiscovery]])
      attempts.  A Registrar signed voucher includes the 'prior-signed-voucher' field
      populated with a Pledge signed voucher that includes a pinned-
      domain-cert that is consistent with unable to complete the Registrar certificate
      chain. transaction
      the first time due to timing reasons will have future chances.

   o  The MASA server is aware of which Pledge's support signing
      of their voucher Pledge requests and can use this information to confirm
      proximity of validates a voucher using the new REST
      calls described below.

   o  If necessary the Pledge with calls the Registrar. EST defined /cacerts method to
      obtain the domain owners' CA certificate.  The root pinned-domain-
      certificate is extracted element from the signature method and used voucher should validate this
      certificate, or be identical to populate the "pinned-domain-cert" of the Voucher being issued. it.

   o  The domain ID (e.g. hash Pledge completes authentication of the public key server certificate as
      detailed in Section 5.5.1.  This moves the BRSKI-EST TLS
      connection out of the domain) is
   extracted from provisional state.  Optionally, the root certificate and is BRSKI-
      EST TLS connection can now be used to update the audit
   log.

3.4.  Voucher Response for EST enrollment.

   The voucher response to requests from the Pledge and requests from extensions for a Registrar are in the same format.  A Registrar either caches prior
   MASA responses or dynamically requests a new Voucher based on local
   policy.

   If the the join operation (equivalent to EST server) are:

   o  Client authentication is successful, automated using Initial Device Identity
      (IDevID) as per the server response MUST
   contain an HTTP 200 response code. EST certificate based client authentication.
      The server subject field's DN encoding MUST answer include the "serialNumber"
      attribute with a
   suitable 4xx or 5xx HTTP [RFC2616] error code when a problem occurs.
   The response data from the MASA server MUST be a plaintext human-
   readable (ASCII, english) error message containing explanatory
   information describing why device's unique serial number.  In the request was rejected.

   Response media type: application/voucher+cms

   The syntactic details language
      of vouchers are described in detail RFC6125 this provides for a SERIALNUM-ID category of identifier
      that can be included in
   [I-D.ietf-anima-voucher].  For example, the voucher consists of:

   {
     "ietf-voucher:voucher": {
       "nonce": "62a2e7693d82fcda2624de58fb6722e5",
       "assertion": "logging"
       "pinned-domain-cert": "<base64 encoded certificate>"
       "serial-number": "JADA123456789"
     }
   } a certificate and therefore that can also
      be used for matching purposes.  The Pledge verifies the signed voucher using the manufacturer
   installed SERIALNUM-ID whitelist is
      collated according to vendor trust anchor associated with the vendor's selected
   Manufacturer Authorized Signing Authority. since serial numbers are
      not globally unique.

   o  The 'pinned-domain-cert' element of Registrar requests and validates the voucher contains Voucher from the domain
   CA's public key. vendor
      authorized MASA service.

   o  The Pledge MUST use Registrar forwards the 'pinned-domain-cert' trust
   anchor Voucher to immediately complete authentication of the provisional TLS
   connection.

   The Pledge MUST be prepared to parse and fail gracefully from an
   Voucher response that does not contain a 'pinned-domain-cert' field. when requested.

   o  The Pledge MUST be prepared Registar performs log verifications in addition to ignore additional fields it does not
   recognize.

3.4.1.  Completing authentication of Provisional local
      authorization checks before accepting optional Pledge device
      enrollment requests.

5.1.  BRSKI-EST TLS establishment details

   The Pledge establishes the TLS connection

   If a Registrar's credentials can not be verified using with the pinned-
   domain-cert trust anchor from Registrar through
   the voucher then circuit proxy (see Section 4) but the TLS connection handshake is
   immediately discarded and the Pledge abandons attempts to bootstrap with this discovered registrar.  The pledge SHOULD send voucher
   status telemetry (described below) before closing the TLS connection.
   Registar.  The pledge MUST attempt to enroll using any other proxies it has
   found.  It SHOULD return to the same proxy again after attempting
   with other proxies.  Attempts should be attempted in BRSKI-EST Pledge is the exponential
   backoff described earlier.  Attempts SHOULD be repeated as failure
   may be TLS client and the result of a temporary inconsistently (an inconsistently
   rolled BRSKI-EST
   Registrar key, or some other mis-configuration).  The
   inconsistently could also be is the result an active MITM attack on TLS server.  All security associations established
   are between the Pledge and the
   EST connection.

   The Registrar MUST use a certificate that chains to regardless of proxy
   operations.

   Establishment of the pinned-
   domain-cert as its BRSKI-EST TLS server certificate.

   The Pledge's PKIX path validation of a Registrar certificate's
   validity period information connection is as described specified in Section 2.4.  Once EST
   [RFC7030] section 4.1.1 "Bootstrap Distribution of CA Certificates"
   [RFC7030] wherein the
   PKIX path validation client is successful authenticated with the TLS connection IDevID
   certificate, and the EST server (the Registrar) is no longer
   provisional.

   The pinned-domain-cert is installed as an Explicit Trust Anchor for
   future operations.  It can therefore can be used to authenticate any
   dynamically discovered EST provisionally
   authenticated with a unverified server that contain certificate.

   The Pledge maintains a security paranoia concerning the id-kp-cmcRA
   extended key usage extension provisional
   state, and all data recieved, until a voucher is received and
   verified as detailed specified in EST RFC7030 section
   3.6.1; but to reduce system complexity the Section 5.5.1

5.2.  Pledge SHOULD avoid
   additional discovery operations.  Instead Requests Voucher from the Registrar

   When the Pledge SHOULD
   communicate directly bootstraps it makes a request for a Voucher from a
   Registrar.

   This is done with an HTTPS POST using the Registrar as the EST server. operation path value of
   "/requestvoucher".

   The '
   pinned-domain-cert' request media types are:

   application/pkcs7-mime; smime-type=voucher-request  The request is not a complete distribution of
      "YANG-defined JSON document that has been signed using a PKCS#7
      structure" as described in Section 3 using the EST section
   4.1.3 CA Certificate Response which JSON encoding
      described in [RFC7951].  The Pledge SHOULD sign the request using
      the Section 2.3 credential.

   application/json  The request is an additional justification
   for the recommendation to proceed "YANG-defined JSON document" as
      described in Section 3 with EST key management operations.
   Once a full CA Certificate Response is obtained exception that it is more
   authoritative for not within a
      PKCS#7 structure.  It is protected only by the domain than TLS client
      authentication.  This reduces the limited 'pinned-domain-cert'
   response.'

3.5.  Voucher Status Telemetry

   The domain cryptographic requirements on
      the Pledge.

   For simplicity the term 'voucher request' is expected used to provide indications refer to either
   of these media types.  Registrar impementations SHOULD anticipate
   future media types but of course will simply fail the system
   administrators concerning device lifecycle status.  To facilitate
   this it needs telemetry information concerning the device's status.

   To indicate request if
   those types are not yet known.

   The Pledge status regarding populates the Voucher voucher request fields as follows:

   created-on:  Pledges that have a realtime clock are RECOMMENDED to
      populate this field.  This provides additional information to the client SHOULD
   post
      MASA.

   nonce:  The voucher request MUST contain a status message. cryptographically strong
      random or pseudo-random number nonce.  Doing so ensures
      Section 2.5 functionality.  The posted data media type: application/json nonce MUST NOT be reused for
      bootstrapping attempts.

   assertion:  The client HTTP POSTs voucher request MAY contain an assertion of
      "proximity".

   proximity-registrar-cert:  In a Pledge voucher request this is the following to
      first certificate in the TLS server at the EST well
   known URI /voucher_status.  The Status field indicates if 'certificate_list' sequence
      (see [RFC5246]) presented by the Voucher
   was acceptable.  If it was not acceptable Registrar to the Reason string indicates
   why.  In Pledge.  This
      MUST be populated in a Pledge's voucher request if the failure case this message "proximity"
      assertion is being sent to an
   unauthenticated, potentially malicious Registrar and therefore populated.

   All other fields MAY be omitted in the
   Reason string SHOULD NOT provide information beneficial to an
   attacker.  The operational benefit voucher request.

   An example JSON payload of this telemetry information a voucher request from a Pledge is
   balanced against in
   Section 3.2 Example 1.

   The Registrar validates the operational costs of not recording that an
   Voucher was ignored by a client identity as described in EST
   [RFC7030] section 3.3.2.  If the registar expected to continue
   joining request is signed the domain.

   {
     "version":"1",
     "Status":FALSE /* TRUE=Success, FALSE=Fail"
     "Reason":"Informative human readable message"
   } Registrar
   confirms the 'proximity' asserion and associated 'proximity-
   registrar-cert' are correct.  The server registrar performs authorization as
   detailed in [[EDNOTE: UNRESOLVED.  See Appendix D "Pledge
   Authorization"]].  If these validations fail the Registrar SHOULD
   respond with an appropriate HTTP 200 but MAY simply fail with
   an HTTP 404 error.  The client ignores any response.  Within the
   server logs the server SHOULD capture this telemetry information.

3.6.  MASA error code.

   If authorization log Request

   A registrar requests is successful the MASA authorization log Registrar obtains a voucher from
   the MASA service
   using this EST extension.  If a device had previously registered with
   another domain, a Registrar of (see Section 5.4) and returns that domain would show in MASA signed
   voucher to the log.

   This pledge as described in Section 5.5.

5.3.  BRSKI-MASA TLS establishment details

   The BRSKI-MASA TLS connection is done with an HTTP GET using the operation path value of
   "/requestauditlog". a 'normal' TLS connection
   appropriate for HTTPS REST interfaces.  The registrar MUST HTTP POSTs Registrar initiates the same Voucher Request
   connection and uses the MASA URL obtained as when
   requesting a Voucher.  It is posted to described in Section 2.7
   for RFC6125 authentication of the /requestauditlog URI
   instead. MASA server.

   The "idevid-issuer" and "serial-number" informs primary method of Registrar "authentication" by the MASA
   server which log is requested so
   detailed in Section 5.4.  As detailed in Section 8 the appropriate log can MASA might
   find it necessary to request additional Registrar authentication.
   Registrars MUST be prepared
   for the response.  Using the same media type and message minimizes
   cryptographic to support TLS client certificate
   authentication and message operations although it results HTTP Basic or Digest authentication as described
   in
   additional network traffic.  The relying RFC7030 for EST clients.  Implementors are advised that contacting
   the MASA server implementation
   MAY leverage internal state is to associate this request establish a secured REST connection with the
   original, a web service
   and by now already validated, voucher request so as to
   avoid an extra crypto validation.

   Request media type: application/voucherrequest+cms

3.7.  MASA authorization log Response

   A log data file is returned consisting of all log entries.  For
   example:

  {
    "version":"1",
    "events":[
      {
       "date":"<date/time that there are a number of the entry>",
       "domainID":"<domainID as extracted from the domain CA certificate authentication models being explored
   within the CMS of the audit voucher request>",
       "nonce":"<any nonce if supplied (or industry.  Registrars are RECOMMENDED to fail gracefully
   and generate useful administrative notifications or logs in the exact string 'NULL')>"
      },
      {
       "date":"<date/time
   advent of the entry>",
       "domainID":"<domainID as extracted unexpected HTTP 401 (Unauthorized) responses from the domain CA certificate
                    within the CMS of the audit MASA.

5.4.  Registrar Requests Voucher from MASA

   When a Registrar receives a voucher request>",
       "nonce":"<any nonce if supplied (or the exact string 'NULL')>"
      }
    ]
  }

   Distribution of request from a large log Pledge it in turn
   requests a voucher from the MASA service.  For simplicity this is less than ideal.  This structure can
   be optimized
   defined as follows: All nonce-less entries for the same domainID
   MAY be condensed into the single most recent nonceless entry.

   A an optional EST message between a Registrar SHOULD use this log information to make and an informed
   decision regarding the continued bootstrapping of EST
   server running on the Pledge.  For
   example if MASA service although the log includes unexpected domainIDs this Registrar is indicative not
   required to make use of problematic imprints by the Pledge.  If any other EST functionality when
   communicating with the log includes nonce-
   less entries this is indicative of the permanent ability for the
   indicated domain MASA service.  (The MASA service MUST properly
   reject any EST functionality requests it does not wish to trigger service; a reset of the device and take over
   management of it.  Equipment
   requirement that holds for any REST interface).

   This is purchased pre-owned can be
   expected to have done with an extensive history.  A Registrar MAY request logs
   at future times.  A Registrar MAY be configured to ignore HTTP POST using the history operation path value of the device but it is RECOMMENDED that this only be configured if
   hardware assisted NEA [RFC5209]
   "/requestvoucher".

   The request media type is:

   application/pkcs7-mime; smime-type=voucher-request  The request is supported.

   Log entries containing the Domain's ID can be compared against local
   history logs in search of discrepancies.

   This a
      "YANG-defined JSON document specifies that has been signed using a simple log format PKCS#7
      structure" as provided by described in [I-D.ietf-anima-voucher] using the MASA
   service JSON
      encoding described in [RFC7951].  The Registrar MUST sign the
      request.  The entire Registrar certificate chain, up to and
      including the registar.  This format could Domain CA, MUST be improved by
   distributed consensus technologies that integrate vouchers with a
   technologies such as block-chain or hash trees or included in the like.  Doing so PKCS#7 structure.

   For simplicity the term 'voucher request' is out used.  MASA
   impementations SHOULD anticipate future media types but of course
   will simply fail the scope of this document but request if those types are anticipated improvements
   for future work.  As such, the not yet known.

   The Registrar client SHOULD anticipate new
   kinds of responses, and SHOULD provide operator controls populates the voucher request fields as follows:

   created-on:  Registrars are RECOMMENDED to indicate
   how to process unknown responses.

3.8.  EST Integration for PKI bootstrapping populate this field.  This section describes EST extensions necessary
      provides additional information to enable fully
   automated bootstrapping.  Although the Voucher request/response
   structure members "idevid-issuer" and "pinned-domain-cert" are
   specific to PKI bootstrapping these are MASA.

   nonce:  The optional nonce value from the only PKI specific aspects Pledge request if desired
      (see below).

   serial-number:  The serial number of the extensions and future Pledge the Registrar would
      like a voucher definitions might replace them
   with non-PKI fields.

   Once for.

   idevid-issuer:  The idevid-issuer value from the Voucher pledge certificate
      is received, as specified in this document, the
   client has sufficient information included to leverage the existing
   communication channel with ensure a Registrar to continue an EST RFC7030
   enrollment. statistically unique identity.  The voucher provides an automated mechanism for
      Pledge's serial number is extracted from the
   "Bootstrap Distribution of CA Certificates" described in [RFC7030]
   section 4.1.1 wherein X.509 IDevID.  See
      Section 2.3.

   prior-signed-voucher:  If the Pledge "MUST [...]. engage provided a human user to
   authorize signed voucher
      request then it SHOULD be included in the CA certificate using out-of-band" information".
   Instead voucher request built by
      the Pledge now can automate Registrar.  (NOTE: this process using is the Pledge's complete voucher
   provided "pinned-domain-cert".

   The Pledge SHOULD use
      request, inclusive of the existing current TLS connection to proceed
   with EST enrollment, thus reducing 'assertion', 'proximity-registrar-cert',
      etc wrapped by the pledge's original PKCS#7 signature).

   A Registrar MAY exclude the nonce from the total amount of cryptographic
   and round trip operations required during bootstrapping.  After voucher verification request it submits
   to the MASA.  Doing so allows the Registrar to request a Voucher when
   the Pledge continues with EST enrollment
   operations including "CA Certificates Request", "CSR Attributes" and
   "Client Certificate Request" is offline, or "Server-Side Key Generation" etc.

   The Pledge when the Registrar is RECOMMENDED expected to implement the following EST automation
   extensions.  They supplement be
   offline when the RFC7030 EST to better support
   automated devices that do not have an end user.

3.8.1.  EST Distribution of CA Certificates

   The Pledge MUST request is being deployed.  These use cases require
   the full EST Distribution of CA Certificates
   message.  See RFC7030, section 4.1.

   This ensures that Registrar to learn the Pledge has appropriate IDevID SerialNumber field from
   the complete set of current CA
   certificates beyond physical device labeling or from the domainCAcert (see Section 3.4 for a
   discussion sales channel (out-of-scope
   of the limitations).  Although these restrictions are
   acceptable for this document).  If a Registrar integrated with initial bootstrapping they
   are nonce is not appropriate for ongoing PKIX end entity certificate
   validation.

3.8.2.  EST CSR Attributes

   Automated bootstrapping occurs without local administrative
   configuration of provided the Pledge.  In some deployments its plausible that MASA server MUST
   authenticate the Pledge generates a certificate request containing only identity
   information known Registrar as described in EST [RFC7030] section
   3.3.2 to reduce the Pledge (essentially the X.509 IDevID
   information) risk of DDoS attacks and ultimately receives a certificate containing domain
   specific to provide an
   authenticated identity information.  Conceptually the CA has complete
   control over all as an input to sales channel integration and
   authorizations (also out-of-scope of this document).

   All other fields issued MAY be omitted in the end entity certificate.
   Realistically this voucher request.

   Example JSON payloads of voucher requests from a Registrar are in
   Section 3.2 Example 2 through 4.

   The MASA verifies that the voucher request is operationally difficult with internally consistent
   but does not authenticate the current status
   of PKI registrar certificate authority deployments where since the CSR
   registrar is submitted not know to the CA via MASA server in advance.  The MASA
   validation checks before issuing a number of non-standard protocols.  Even with all
   standardized protocols used, it could operationally be problematic voucher are as follows:

   Renew for expired voucher:  As described in [I-D.ietf-anima-voucher]
      vouchers are normally short lived to
   expect that service specific certificate fields can be created avoid revocation issues.  If
      the request is for a previous (expired) voucher using the same
      Registrar (as determined by the Registrar pinned-domain-cert) and
      the MASA has not been informed that the claim is invalid then the
      request for a
   CA renewed voucher SHOULD be automatically authorized.

   Voucher signature consistency:  The MASA MUST verify that the voucher
      request is likely operated signed by a group Registrar.  This is confirmed by verifying
      that has no insight into
   different network services/protocols used.  For example, the CA could
   even be outsourced.

   To alleviate these operational difficulties, id-kp-cmcRA extended key usage extension field (as
      detailed in EST RFC7030 section 3.6.1) exists in the Pledge MUST request certificate
      of the EST "CSR Attributes" from entity that signed the EST server and voucher request.  This verification
      is only a consistency check that the EST server needs unauthenticated domain CA
      intended this to be able a Registrar.  Performing this check provides
      value to reply with domain PKI by assuring the attributes necessary for use domain administrator that the
      MASA service will only respect claims from authorized Registration
      Authorities of the
   certificate in its intended protocols/services.  This approach allows domain.  (The requirement for minimal CA integrations and instead the local infrastructure (EST
   server) informs the Pledge of the proper fields Registrar to
      include the Domain CA certificate in the
   generated CSR.  This approach is beneficial to automated boostrapping
   in signature structure was
      stated above).

   Registrar revocation consistency:  The MASA SHOULD check for
      revocation of the widest number Registrar certificate.  The maximum lifetime of environments.

   If
      the hardwareModuleName in voucher issued SHOULD NOT exceed the X.509 IDevID lifetime of the
      Registrar's revocation validation (for example if the Registrar
      revocation status is populated indicated in a CRL that is valid for two
      weeks then it
   SHOULD by default be propagated to the LDevID along with that is an appropriate lifetime for the
   hwSerialNum.  The EST server SHOULD support local policy concerning
   this functionality.

   In networks using voucher).
      Because the BRSKI enrolled Registar certificate authority is unknown to authenticate the
   ACP (Autonomic Control Plane), MASA
      in advance this is only an extended consistency check and is not
      required.  The maximum lifetime of the EST attributes MUST include voucher issued SHOULD NOT
      exceed the
   "ACP information" field.  See
   [I-D.ietf-anima-autonomic-control-plane] for more details.

   The Registar MUST also confirm lifetime of the resulting CSR Registrar's revocation validation (for
      example if the Registrar revocation status is formatted as indicated before forwarding the request to in a CA.  If CRL
      that is valid for two weeks then that is an appropriate lifetime
      for the Registar voucher).

   Pledge proximity assertion:  The MASA server MAY verify that the
      Registrar signed voucher includes the 'prior-signed-voucher' field
      populated with a Pledge signed voucher that includes a 'proximity-
      registrar-cert' that is
   communicating consistent with the CA using a protocol like full CMC which
   provides mechanisms to override certificate the CSR attributes, then these
   mechanisms MAY be
      Registrar used even if to sign the client ignores CSR Attribute
   guidance.

3.8.3.  EST Client Certificate Request voucher request.  The Pledge MUST request a new client certificate.  See RFC7030,
   section 4.2.

3.8.4.  Enrollment Status Telemetry

   For automated bootstrapping MASA server is
      aware of devices the adminstrative elements
   providing bootstrapping also provide indications which Pledge's support signing of their voucher requests
      and can use this information to confirm proximity of the system
   administrators concerning device lifecycle status.  This might
   include information concerning attempted bootstrapping messages seen
   by Pledge
      with the client, MASA provides logs and status of credential
   enrollment. Registrar.

   The EST protocol assumes an end user Registrar certificate chain root certificate is extracted from
   the signature method and therefore does
   not include a final success indication back used to populate the server.  This is
   insufficient for automated use cases.

   To indicate successful enrollment "pinned-domain-cert" of
   the client SHOULD re-negotiate Voucher being issued.  The domain ID (e.g. hash of the
   EST TLS session using public key
   of the newly obtained credentials.  This occurs by domain) is extracted from the client initiating a new TLS ClientHello message on root certificate and is used to
   update the existing
   TLS connection. audit log.

5.5.  Voucher Response

   The client MAY simply close voucher response to requests from the old TLS session Pledge and
   start requests from a
   Registrar are in the same format.  A Registrar either caches prior
   MASA responses or dynamically requests a new one. Voucher based on local
   policy.

   If the join operation is successful, the server response MUST contain
   an HTTP 200 response code.  The server MUST support either model.

   In the case of answer with a FAIL the Reason string indicates why the most recent
   enrollment failed. suitable
   4xx or 5xx HTTP [RFC2616] error code when a problem occurs.  The SubjectKeyIdentifier field
   response data from the MASA server MUST be included
   if a plaintext human-readable
   (ASCII, english) error message containing explanatory information
   describing why the enrollment attempt request was rejected.

   A 403 (Forbidden) response is appropriate if the voucher request is
   not signed correctly, stale, or if the pledge has another outstanding
   voucher which can not be overridden.

   A 404 (Not Found) response is appropriate when the request is for a keypair that
   device which is locally not known to the client.  If EST /serverkeygen was used MASA.

   A 406 (Not Acceptable) response is appropriate if a voucher of the
   desired type, or using the desired algorithms (as indicated by the
   Accept: headers, and failed then algorithms used in the field
   is omitted from signature) can not be
   issued, such as because the status telemetry.

   In MASA knows the case of pledge can not process
   that type.

   A 415 (Unsupported Media Type) response is approriate for a SUCCESS the Reason string request
   that has a voucher encoding that is omitted. not understood.

   The
   SubjectKeyIdentifier response media type is:

   application/pkcs7-mime; smime-type=voucher  The response is included so a "YANG-
      defined JSON document that has been signed using a PKCS#7
      structure" as described in [I-D.ietf-anima-voucher] using the server can record the
   successful certificate distribution.

   Status media type: application/json JSON
      encoded described in [RFC7951].  The client HTTP POSTs the following to MASA MUST sign the server at request.

   The syntactic details of vouchers are described in detail in
   [I-D.ietf-anima-voucher].  For example, the new EST well
   known URI /enrollstatus. voucher consists of:

   {
    "version":"1",
    "Status":TRUE /* TRUE=Success, FALSE=Fail"
    "Reason":"Informative human readable message"
    "SubjectKeyIdentifier":"<base64 encoded subjectkeyidentifier for the
                             enrollment that failed>"
     "ietf-voucher:voucher": {
       "nonce": "62a2e7693d82fcda2624de58fb6722e5",
       "assertion": "logging"
       "pinned-domain-cert": "base64encodedvalue=="
       "serial-number": "JADA123456789"
     }
   }

   The server SHOULD respond with an HTTP 200 but MAY simply fail with
   an HTTP 404 error.

   Within Pledge verifies the server logs signed voucher using the server MUST capture if this message was
   received over an TLS session manufacturer
   installed trust anchor associated with a matching client certificate.
   This allows for clients that wish to minimize their crypto operations
   to simply POST this response without renegotiating the TLS session -
   at the cost vendor's selected
   Manufacturer Authorized Signing Authority.

   The 'pinned-domain-cert' element of the server not being able to accurately verify that
   enrollment was truly successful.

3.8.5.  EST over CoAP

   This document describes extensions to EST for voucher contains the purposes of
   bootstrapping of remote key infrastructures.  Bootstrapping is
   relevant for CoAP enrollment discussions as well. domain
   CA's public key.  The defintion Pledge MUST use the 'pinned-domain-cert' trust
   anchor to immediately complete authentication of
   EST the provisional TLS
   connection.

   The Pledge MUST be prepared to parse and BRSKI over CoAP is not discussed within this document beyond
   ensuring proxy support for CoAP operations.  Instead it is
   anticipated that fail gracefully from a definition of CoAP mappings will occur in
   subsequent documents such as [I-D.vanderstok-ace-coap-est] and
   Voucher response that
   CoAP mappings for BRSKI will does not contain a 'pinned-domain-cert' field.
   The Pledge MUST be discussed either there or in future
   work.

4.  Reduced security operational modes

   A common requirement prepared to ignore additional fields it does not
   recognize.

5.5.1.  Completing authentication of bootstrapping Provisional TLS connection

   If a Registrar's credentials can not be verified using the pinned-
   domain-cert trust anchor from the voucher then the TLS connection is
   immediately discarded and the Pledge abandons attempts to support less secure
   operational modes for support specific use cases. bootstrap
   with this discovered registrar.  The following
   sections detail specific ways that pledge SHOULD send voucher
   status telemetry (described below) before closing the Pledge, Registrar and MASA can
   be configured TLS connection.
   The pledge MUST attempt to run enroll using any other proxies it has
   found.  It SHOULD return to the same proxy again after attempting
   with other proxies.  Attempts should be attempted in a less secure mode for the indicated reasons.

4.1.  Trust Model
   +--------+         +---------+    +------------+     +------------+
   | Pledge |         | Circuit |    | Domain     |     | Vendor     |
   |        |         | Proxy   |    | exponential
   backoff described earlier.  Attempts SHOULD be repeated as failure
   may be the result of a temporary inconsistently (an inconsistently
   rolled Registrar  |     | Service    |
   |        |         |         |    |            |     | (Internet  |
   +--------+         +---------+    +------------+     +------------+

   Figure 10

   Pledge: key, or some other mis-configuration).  The Pledge
   inconsistently could also be compromised and providing the result an active MITM attack
      vector for malware. on the
   EST connection.

   The entity is trusted to only imprint using
      secure methods described in this document.  Additional endpoint
      assessment techniques are RECOMMENDED but are out-of-scope of this
      document.

   Proxy:  Provides proxy functionalities but is not involved in
      security considerations.

   Registrar:  When interacting with Registrar MUST use a MASA certificate that chains to the pinned-
   domain-cert as its TLS server certificate.

   The Pledge's PKIX path validation of a Registrar makes all
      decisions.  When Ownership Vouchers are involved a Registrar certificate's
   validity period information is
      only a conduit and all security decisions are made on as described in Section 2.5.  Once the vendor
      service.

   Vendor Service, MASA:  This form of vendor service
   PKIX path validation is trusted to
      accurately log all claim attempts and to provide authoritative log
      information to Registrars.  The MASA does not know which devices
      are associated with which domains.  These claims could be
      strengthened by using cryptographic log techniques to provide
      append only, cryptographic assured, publicly auditable logs.
      Current text provides only for a trusted vendor.

   Vendor Service, Ownership Validation:  This form of vendor service is
      trusted to accurately know which device successful the TLS connection is owned by which domain.

4.2.  Pledge security reductions no longer
   provisional.

   The Pledge pinned-domain-cert is installed as an Explicit Trust Anchor for
   future operations.  It can choose therefore can be used to accept vouchers using less secure methods.
   These methods enable offline and emergency (touch based) deployment
   use cases:

   1.  The authenticate any
   dynamically discovered EST server that contain the id-kp-cmcRA
   extended key usage extension as detailed in EST RFC7030 section
   3.6.1; but to reduce system complexity the Pledge MUST accept nonceless vouchers.  This allows for
       offline use cases.  Logging and validity periods address SHOULD avoid
   additional discovery operations.  Instead the
       inherent security considerations of supporting these use cases.

   2.  The Pledge MAY support "trust on first use" for physical
       interfaces such SHOULD
   communicate directly with the Registrar as a local console port or physical user
       interface but MUST NOT support "trust on first use" on network
       interfaces.  This is because "trust on first use" permanently
       degrades the security for all use cases.

   3. EST server.  The Pledge MAY have an operational mode where it skips Voucher
       validation one time.  For example if a physical button '
   pinned-domain-cert' is
       depressed during the bootstrapping operation.  This can be useful
       if not a complete distribution of the vendor service EST section
   4.1.3 CA Certificate Response which is unavailable.  This behavior SHOULD be
       available via local configuration or physical presence methods to
       ensure new entities can always be deployed even when autonomic
       methods fail.  This allows an additional justification
   for unsecured imprint.

   It the recommendation to proceed with EST key management operations.
   Once a full CA Certificate Response is RECOMMENDED that "trust on first use" or skipping voucher
   validation only be available if hardware assisted Network Endpoint
   Assessment [RFC5209] obtained it is supported.  This recommendation ensures that more
   authoritative for the domain network monitoring can detect innappropriate use of offline or
   emergency deployment procedures.

4.3.  Registrar security reductions

   A Registrar can choose than the limited 'pinned-domain-cert'
   response.'

5.6.  Voucher Status Telemetry

   The domain is expected to provide indications to accept devices using less secure methods.
   These methods are acceptable when low security models are needed, as the security decisions are being made by system
   administrators concerning device lifecycle status.  To facilitate
   this it needs telemetry information concerning the local administrator, but
   they MUST NOT be device's status.

   To indicate Pledge status regarding the default behavior:

   1.  A registrar MAY choose to accept all devices, or all devices of Voucher, the pledge MUST post
   a
       particular type, at status message.

   The posted data media type: application/json

   The client HTTP POSTs the administrator's discretion.  This could
       occur when informing all Registrars of unique identifiers of new
       entities might be operationally difficult.

   2.  A registrar MAY choose following to accept devices that claim a unique
       identity without the benefit of authenticating that claimed
       identity.  This could occur when server at the Pledge does not include an
       X.509 IDevID factory installed credential.  New Entities without
       an X.509 IDevID credential MAY form EST well
   known URI /voucher_status.  The Status field indicates if the Section 3.2 request using Voucher
   was acceptable.  If it was not acceptable the Section 3.3 format to ensure Reason string indicates
   why.  In the Pledge's serial number
       information failure case this message is provided being sent to an
   unauthenticated, potentially malicious Registrar and therefore the Registar (this includes the IDevID
       AuthorityKeyIdentifier value which would be statically configured
       on the Pledge).  The Pledge MAY refuse to provide a TLS client
       certificate (as one is not available).  The Pledge
   Reason string SHOULD support
       HTTP-based or certificate-less TLS authentication as described in
       EST RFC7030 section 3.3.2.  A Registrar MUST NOT accept
       unauthenticated New Entities unless it has been configured provide information beneficial to do
       so by an administrator that has verified that only expected new
       entities can communicate with a Registrar (presumably via a
       physically secured perimeter).

   3.  A Registrar MAY request nonce-less Vouchers from
   attacker.  The operational benefit of this telemetry information is
   balanced against the MASA service
       (by operational costs of not including recording that an
   Voucher was ignored by a nonce in client the request).  These Vouchers can
       then be transmitted registar expected to continue
   joining the Registrar and stored until they are
       needed during bootstrapping operations.  This is for use cases
       where target network is protected by domain.

   {
     "version":"1",
     "Status":FALSE /* TRUE=Success, FALSE=Fail"
     "Reason":"Informative human readable message"
     "reason-context": { additional JSON }
   }

   The server SHOULD respond with an air gap and therefore can
       not contact the MASA service during Pledge deployment.

   4.  A registrar HTTP 200 but MAY ignore unrecognized nonce-less log entries.  This
       could occur when used equipment is purchased simply fail with a valid history
       being deployed in air gap networks that required permanent
       Vouchers.

4.4.  MASA security reductions

   Lower security modes chosen by
   an HTTP 404 error.  The client ignores any response.  Within the MASA service effect all device
   deployments unless bound to
   server logs the specific device identities.  In server SHOULD capture this telemetry information.

   The reason-context attribute is an arbitrary JSON object (literal
   value or hash of values) which
   case these modes can be provided as provides additional features for information
   specific
   customers. to this pledge.  The contents of this field are not subject
   to standardization."

   Additional standard responses MAY be added via Specification
   Required.

5.7.  MASA authorization log Request

   After receiving the voucher status telemetry Section 5.6, the
   Registrar SHOULD request the MASA authorization log from the MASA
   service can choose to run in less secure modes
   by:

   1.  Not enforcing that using this EST extension.  If a nonce is in the Voucher.  This results in
       distribution device had previously
   registered with another domain, a Registrar of Voucher that never expires and domain would show
   in effect makes the Domain log.

   This is done with an always trusted entity to HTTP GET using the Pledge during any
       subsequent bootstrapping attempts.  That this occurred operation path value of
   "/requestauditlog".

   The registrar MUST HTTP POSTs the same Voucher Request as when
   requesting a Voucher.  It is
       captured in posted to the /requestauditlog URI
   instead.  The "idevid-issuer" and "serial-number" informs the MASA
   server which log information is requested so that the Domain registrar can
       make appropriate security decisions when a Pledge joins the
       Domain.  This is useful to support use cases where Registrars
       might not log can be online during actual device deployment.  Because
       this results in long lived Voucher and does not require the proof
       that the device is online this is only accepted when prepared
   for the
       Registrar is authenticated by response.  Using the MASA server same media type and authorized to
       provide this functionality. message minimizes
   cryptographic and message operations although it results in
   additional network traffic.  The relying MASA server is RECOMMENDED implementation
   MAY leverage internal state to
       use associate this functionality only in concert request with an enhanced level of
       ownership tracking (out-of-scope).  If the Pledge device is known
       to have a real-time-clock that is set from the factory use of a
   original, and by now already validated, voucher validity period is RECOMMENDED.

   2.  Not verifying ownership before responding with request so as to
   avoid an Voucher.  This extra crypto validation.

   The request media type is:

   application/pkcs7-mime; smime-type=voucher-request  The request is expected to be a common operational model because doing so
       relieves the vendor providing MASA services from having to track
       ownership during shipping and supply chain and allows for
      "YANG-defined JSON document that has been signed using a very
       low overhead MASA service.  A Registrar uses the audit log
       information PKCS#7
      structure" as a defense described in depth strategy to ensure that this
       does not occur unexpectedly (for example when purchasing new
       equipment Section 3 using the JSON encoded
      described in [RFC7951].  The Registrar would throw an error if any audit log
       information is reported). MUST sign the request.  The MASA should verify
      entire Registrar certificate chain, up to and including the 'prior-
       signed-voucher' information for Pledge's that support that
       functionality.  This provides a proof-of-proximity check that
       reduces Domain
      CA, MUST be included in the need for ownership verification.

5.  IANA Considerations

5.1.  PKIX Registry

   This document requests a number for id-mod-MASAURLExtn2016(TBD) PKCS#7 structure.

5.7.1.  MASA authorization log Response

   A log data file is returned consisting of all log entries.  For
   example:

  {
    "version":"1",
    "events":[
      {
       "date":"<date/time of the entry>",
       "domainID":"<domainID as extracted from the pkix(7) id-mod(0) Registry.  [[EDNOTE: fix names]]

   This document requests a number domain CA certificate
                    within the CMS of the audit voucher request>",
       "nonce":"<any nonce if supplied (or the exact string 'NULL')>"
      },
      {
       "date":"<date/time of the entry>",
       "domainID":"<domainID as extracted from the id-pe registry domain CA certificate
                    within the CMS of the audit voucher request>",
       "nonce":"<any nonce if supplied (or the exact string 'NULL')>"
      }
    ]
  }

   Distribution of a large log is less than ideal.  This structure can
   be optimized as follows: All nonce-less entries for id-pe-
   masa-url.  XXX

6.  Security Considerations

   There are uses cases where the MASA could same domainID
   MAY be unavailable or
   uncooperative to condensed into the Registrar.  They include planned and unplanned
   network partitions, changes single most recent nonceless entry.

   A Registrar SHOULD use this log information to MASA policy, or other instances where
   MASA policy rejects a claim.  These introduce make an operational risk to informed
   decision regarding the Registrar owner that MASA/vendor behavior might limit continued bootstrapping of the ability
   to re-boostrap a Pledge device. Pledge.  For
   example if the log includes unexpected domainIDs this might be an issue
   during disaster recovery.  This risk can be mitigated is indicative
   of problematic imprints by Registrars
   that request and maintain long term copies the Pledge.  If the log includes nonce-
   less entries this is indicative of "nonceless" Vouchers.
   In that way they are guaranteed to be able to repeat bootstrapping the permanent ability for their devices.

   The issuance of nonceless vouchers themselves create a security
   concern.  If the Registrar of a previous
   indicated domain can intercept
   protocol communications then it can use a previously issued nonceless
   voucher to establish management control of trigger a pledge reset of the device even after
   having sold and take over
   management of it.  This risk  Equipment that is mitigated by recording purchased pre-owned can be
   expected to have an extensive history.  A Registrar MAY request logs
   at future times.  A Registrar MAY be configured to ignore the issuance history
   of
   such vouchers in the MASA audit log device but it is RECOMMENDED that this only be configured if
   hardware assisted NEA [RFC5209] is verified by the
   subsequent Registrar.  This reduces the resale value of the equipment
   because future owners will detect supported.

   Log entries containing the lowered security inherent Domain's ID can be compared against local
   history logs in
   the existence search of a nonceless voucher that would be trusted by their
   Pledge. discrepancies.

   This reflects document specifies a balance between partition resistant recovery
   and security of future bootstrapping.  Registrars take simple log format as provided by the Pledge's
   audit history into account when applying policy to new devices.

   The MASA server is exposed
   service to DoS attacks wherein attackers claim an
   unbounded number of devices.  Ensuring the registar.  This format could be improved by
   distributed consensus technologies that integrate vouchers with a Registrar
   technologies such as block-chain or hash trees or the like.  Doing so
   is representative out of a valid vendor customer, even without validating ownership the scope of
   specific Pledge devices, helps this document but are anticipated improvements
   for future work.  As such, the Registrar client SHOULD anticipate new
   kinds of responses, and SHOULD provide operator controls to mitigate this. indicate
   how to process unknown responses.

5.8.  EST Integration for PKI bootstrapping

   The Pledge signatures
   on SHOULD follow the initial voucher request, as forwarded by BRSKI operations with EST enrollment
   operations including "CA Certificates Request", "CSR Attributes" and
   "Client Certificate Request" or "Server-Side Key Generation" etc.
   This is a relatively seamless integration since BRSKI REST calls
   provide an automated alternative to the Registrar manual bootstrapping method
   described in the
   prior-signed-voucher field, significantly reduce this risk by
   ensuring the MASA can confirm proximity between [RFC7030].  As noted above, use of HTTP 1.1 persistent
   connections simplifies the Pledge and state machine.

   The Pledge is also RECOMMENDED to implement the
   Registrar making following EST
   automation extensions.  They supplement the request.  This mechanism is optional RFC7030 EST to allow
   for constrained devices.

   It is possible for better
   support automated devices that do not have an attacker end user.

   Although EST allows clients to request a voucher from obtain multiple certificates by
   sending multiple CSR requests BRSKI mandates use of the MASA
   service directly after CSR
   Attributes request and mandates that the real Registrar obtains an audit log.  If validate the attacker could also force CSR
   against the bootstrapping protocol to reset
   there is expected attributes.  This implies that client requests
   will "look the same" and therefore result in a theoretical opportunity for single logical
   certificate being issued even if the attacker to use their
   voucher client were to take control of the Pledge make multiple
   requests.  Registrars MAY contain more complex logic but then proceed doing so is
   out-of-scope of this specification.  BRSKI does not signal any
   enhancement or restriction to this capability.  Pledges that require
   multiple certificates could establish direct EST connections to enroll with
   the target domain.  Possible prevention mechanisms include:

   o  Per device rate limits on the MASA service ensure such timing
      attacks are difficult.

   o
   Registrar.

5.8.1.  EST Distribution of CA Certificates

   The Registrar can repeat the Pledge MUST request for audit log information at
      some time after bootstrapping is complete.

   To facilitate logging and administrative oversight the Pledge reports
   on Voucher parsing status to full EST Distribution of CA Certificates
   message.  See RFC7030, section 4.1.

   This ensures that the Registrar.  In Pledge has the case complete set of current CA
   certificates beyond the pinned-domain-cert (see Section 5.5.1 for a failure
   this information is informative to a potentially malicious Registar
   but this is RECOMMENDED anyway because
   discussion of the operational benefits of
   an informed administrator limitations inherent in cases where the failure is indicative having a single certificate
   instead of a problem.

   To facilitate truely limited clients full CA Certificates response).  Although these
   limitations are acceptable during initial bootstrapping they are not
   appropriate for ongoing PKIX end entity certificate validation.

5.8.2.  EST RFC7030 section 3.3.2
   requirements that CSR Attributes

   Automated bootstrapping occurs without local administrative
   configuration of the client MUST support a client authentication
   model have been reduced in Section 4 to a statement Pledge.  In some deployments its plausible that
   the
   Registrar "MAY" choose to accept devices that fail cryptographic
   authentication.  This reflects current (poor) practices in shipping
   devices without Pledge generates a cryptographic certificate request containing only identity that are NOT RECOMMENDED.

   During
   information known to the provisional period of Pledge (essentially the connection all HTTP header X.509 IDevID
   information) and
   content data MUST treated as untrusted data.  HTTP libraries are
   regularly exposed to non-secured HTTP traffic: mature libraries
   should not have any problems.

   Pledge's might chose to engage ultimately receives a certificate containing domain
   specific identity information.  Conceptually the CA has complete
   control over all fields issued in protocol operations the end entity certificate.
   Realistically this is operationally difficult with multiple
   discovered Registrars in parallel.  As noted above they will only do
   so the current status
   of PKI certificate authority deployments where the CSR is submitted
   to the CA via a number of non-standard protocols.  Even with distinct nonce values, but all
   standardized protocols used, it could operationally be problematic to
   expect that service specific certificate fields can be created by a
   CA that is likely operated by a group that has no insight into
   different network services/protocols used.  For example, the end result CA could
   even be multple
   voucher's issued outsourced.

   To alleviate these operational difficulties, the Pledge MUST request
   the EST "CSR Attributes" from the MASA if all registrars attempt EST server and the EST server needs
   to claim be able to reply with the
   device. attributes necessary for use of the
   certificate in its intended protocols/services.  This is not a failure approach allows
   for minimal CA integrations and instead the local infrastructure (EST
   server) informs the Pledge choses whichever
   voucher to accept based on internal logic.  The Registrar's verifying
   log information will see multiple entries and take this into account
   for their analytics purposes.

7.  Acknowledgements

   We would like of the proper fields to thank include in the various reviewers for their input,
   generated CSR.  This approach is beneficial to automated boostrapping
   in
   particular Brian Carpenter, Toerless Eckert, Fuyu Eleven, Eliot Lear,
   Sergey Kasatkin, Markus Stenberg, and Peter van der Stok

8.  References

8.1.  Normative References

   [I-D.ietf-anima-autonomic-control-plane]
              Behringer, M., Eckert, T., and S. Bjarnason, "An Autonomic
              Control Plane", draft-ietf-anima-autonomic-control-
              plane-06 (work in progress), March 2017.

   [I-D.ietf-anima-voucher]
              Watsen, K., Richardson, M., Pritikin, M., and T. Eckert,
              "Voucher Profile for Bootstrapping Protocols", draft-ietf-
              anima-voucher-04 (work in progress), July 2017.

   [I-D.vanderstok-ace-coap-est]
              Kumar, S., Stok, P., Kampanakis, P., Furuhed, M., and S.
              Raza, "EST over secure CoAP (EST-coaps)", draft-
              vanderstok-ace-coap-est-02 (work in progress), June 2017.

   [IDevID]   IEEE Standard, "IEEE 802.1AR Secure Device Identifier",
              December 2009, <http://standards.ieee.org/findstds/
              standard/802.1AR-2009.html>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC3542]  Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei,
              "Advanced Sockets Application Program Interface (API) for
              IPv6", RFC 3542, DOI 10.17487/RFC3542, May 2003,
              <http://www.rfc-editor.org/info/rfc3542>.

   [RFC3748]  Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
              Levkowetz, Ed., "Extensible Authentication Protocol
              (EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004,
              <http://www.rfc-editor.org/info/rfc3748>.

   [RFC3927]  Cheshire, S., Aboba, B., and E. Guttman, "Dynamic
              Configuration of IPv4 Link-Local Addresses", RFC 3927,
              DOI 10.17487/RFC3927, May 2005,
              <http://www.rfc-editor.org/info/rfc3927>.

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862,
              DOI 10.17487/RFC4862, September 2007,
              <http://www.rfc-editor.org/info/rfc4862>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <http://www.rfc-editor.org/info/rfc5246>.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
              <http://www.rfc-editor.org/info/rfc5280>.

   [RFC5386]  Williams, N. and M. Richardson, "Better-Than-Nothing
              Security: An Unauthenticated Mode of IPsec", RFC 5386,
              DOI 10.17487/RFC5386, November 2008,
              <http://www.rfc-editor.org/info/rfc5386>.

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
              RFC 5652, DOI 10.17487/RFC5652, September 2009,
              <http://www.rfc-editor.org/info/rfc5652>.

   [RFC5660]  Williams, N., "IPsec Channels: Connection Latching",
              RFC 5660, DOI 10.17487/RFC5660, October 2009,
              <http://www.rfc-editor.org/info/rfc5660>.

   [RFC6762]  Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
              DOI 10.17487/RFC6762, February 2013,
              <http://www.rfc-editor.org/info/rfc6762>.

   [RFC6763]  Cheshire, S. and M. Krochmal, "DNS-Based Service
              Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
              <http://www.rfc-editor.org/info/rfc6763>.

   [RFC7030]  Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
              "Enrollment over Secure Transport", RFC 7030,
              DOI 10.17487/RFC7030, October 2013,
              <http://www.rfc-editor.org/info/rfc7030>.

   [RFC7228]  Bormann, C., Ersue, M., and A. Keranen, "Terminology for
              Constrained-Node Networks", RFC 7228,
              DOI 10.17487/RFC7228, May 2014,
              <http://www.rfc-editor.org/info/rfc7228>.

   [RFC7951]  Lhotka, L., "JSON Encoding of Data Modeled with YANG",
              RFC 7951, DOI 10.17487/RFC7951, August 2016,
              <http://www.rfc-editor.org/info/rfc7951>.

8.2.  Informative References

   [I-D.behringer-homenet-trust-bootstrap]
              Behringer, M., Pritikin, M., and S. Bjarnason,
              "Bootstrapping Trust on a Homenet", draft-behringer-
              homenet-trust-bootstrap-02 (work in progress), February
              2014.

   [I-D.ietf-anima-grasp]
              Bormann, C., Carpenter, B., and B. Liu, "A Generic
              Autonomic Signaling Protocol (GRASP)", draft-ietf-anima-
              grasp-13 (work in progress), June 2017.

   [I-D.ietf-netconf-zerotouch]
              Watsen, K., Abrahamsson, M., and I. Farrer, "Zero Touch
              Provisioning for NETCONF or RESTCONF based Management",
              draft-ietf-netconf-zerotouch-14 (work in progress), June
              2017.

   [I-D.lear-mud-framework]
              Lear, E., "Manufacturer Usage Description Framework",
              draft-lear-mud-framework-00 (work in progress), January
              2016.

   [I-D.richardson-anima-state-for-joinrouter]
              Richardson, M., "Considerations for stateful vs stateless
              join router in ANIMA bootstrap", draft-richardson-anima-
              state-for-joinrouter-01 (work in progress), July 2016.

   [imprinting]
              Wikipedia, "Wikipedia article: Imprinting", July 2015,
              <https://en.wikipedia.org/wiki/Imprinting_(psychology)>.

   [RFC2473]  Conta, A. and S. Deering, "Generic Packet Tunneling in
              IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473,
              December 1998, <http://www.rfc-editor.org/info/rfc2473>.

   [RFC7217]  Gont, F., "A Method for Generating Semantically Opaque
              Interface Identifiers with IPv6 Stateless Address
              Autoconfiguration (SLAAC)", RFC 7217,
              DOI 10.17487/RFC7217, April 2014,
              <http://www.rfc-editor.org/info/rfc7217>.

   [RFC7435]  Dukhovni, V., "Opportunistic Security: Some Protection
              Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
              December 2014, <http://www.rfc-editor.org/info/rfc7435>.

   [RFC7575]  Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,
              Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
              Networking: Definitions and Design Goals", RFC 7575,
              DOI 10.17487/RFC7575, June 2015,
              <http://www.rfc-editor.org/info/rfc7575>.

   [Stajano99theresurrecting]
              Stajano, F. and R. Anderson, "The resurrecting duckling:
              security issues for ad-hoc wireless networks", 1999,
              <https://www.cl.cam.ac.uk/~fms27/papers/1999-StajanoAnd-
              duckling.pdf>.

Appendix A.  IPv4 operations

A.1.  IPv4 Link Local addresses

   Instead of an IPv6 link-local address, an IPv4 address may be
   generated using [RFC3927]  Dynamic Configuration of IPv4 Link-Local
   Addresses.

   In the case that an IPv4 Local-Local address is formed, then the
   bootstrap process would continue as in the IPv6 case by looking for a
   (circuit) proxy.

A.2.  Use of DHCPv4

   The Plege MAY obtain an IP address via DHCP [RFC2131].  The DHCP
   provided parameters for the Domain Name System can be used to perform
   DNS operations if all local discovery attempts fail.

Appendix B.  mDNS / DNSSD proxy discovery options

   The Pledge MAY perform DNS-based Service Discovery [RFC6763] over
   Multicast DNS [RFC6762] searching for the service
   "_bootstrapks._tcp.local.".

   To prevent unaccceptable levels of network traffic the congestion
   avoidance mechanisms specified in [RFC6762] section 7 MUST be
   followed.  The Pledge SHOULD listen for an unsolicited broadcast
   response as described in [RFC6762].  This allows devices to avoid
   announcing their presence via mDNS broadcasts and instead silently
   join a network by watching for periodic unsolicited broadcast
   responses.

   Performs DNS-based Service Discovery [RFC6763] over normal DNS
   operations.  The service searched for is
   "_bootstrapks._tcp.example.com".  In this case the domain
   "example.com" is discovered as described in [RFC6763] section 11.

   This method is only available if the host has received a useable IPv4
   address via DHCPv4 as suggested in Appendix A.

   If no local bootstrapks service is located using the GRASP
   mechanisms, or the above mentioned DNS-based Service Discovery
   methods the Pledge MAY contact a well known vendor provided
   bootstrapping server by performing a DNS lookup using a well known
   URI such as "bootstrapks.vendor-example.com".  The details of the URI
   are vendor specific.  Vendors that leverage this method on the Pledge
   are responsible for providing the bootstrapks service.

   The current DNS services returned during each query is maintained
   until bootstrapping is completed.  If bootstrapping fails and the
   Pledge returns to the Discovery state it picks up where it left off
   and continues attempting bootstrapping.  For example if the first
   Multicast DNS _bootstrapks._tcp.local response doesn't work then the
   second and third responses are tried.  If these fail the Pledge moves
   on to normal DNS-based Service Discovery.

Appendix C.  IPIP Join Proxy mechanism

   The Circuit Proxy mechanism suffers from requiring a state on the
   Join Proxy for each connection that is relayed.  The Circuit Proxy
   can be considered a kind of Algorithm Gateway [FIND-good-REF].

   An alternative to proxying at the TCP layer is to selectively forward
   at the IP layer.  This moves all per-connection to the Join
   Registrar.  The IPIP tunnel statelessly forwards packets.  This
   section provides some explanation of some of the details of the
   Registrar discovery procotol which are not important to Circuit
   Proxy, and some implementation advice.

   The IPIP tunnel is described in [RFC2473].  Each such tunnel is
   considered a unidirectional construct, but two tunnels may be
   associated to form a bidirectional mechanism.  An IPIP tunnel is
   setup as follows.  The outer addresses are an ACP address of the Join
   Proxy, and the ACP address of the Join Registrar.  The inner
   addresses seen in the tunnel are the link-local addresses of the
   network on which the join activity is occuring.

   One way to look at this construct is to consider that the Registrar
   is extending attaching an interface to the network on which the Join
   Proxy is physically present.  The Registrar then interacts as if it
   were present on that network using link-local (fe80::) addresses.
   The Join node is unaware that the traffic is being proxied through a
   tunnel, and does not need any special routing.

   There are a number of considerations with this mechanism which
   require cause some minor amounts of complexity.  Note that due to the
   tunnels, the Registrar sees multiple connections to a fe80::/10
   network on not just physical interfaces, but on each of the virtual
   interfaces represending the tunnels.

C.1.  Multiple Join networks on the Join Proxy side

   The Join Proxy will in the general case be a routing device with
   multiple interfaces.  Even a device as simple as a wifi access point
   may have wired, and multiple frequencies of wireless interfaces,
   potentially with multiple ESSIDs.

   Each of these interfaces on the Join Proxy may be seperate L3 routing
   domains, and therefore will have a unique set of link-local
   addresses.  An IPIP packet being returned by the Registrar needs to
   be forwarded to the correct interface, so the Join Proxy needs an
   additional key to distinguish which network the packet should be
   returned to.

   The simplest way to get this additional key is to allocate an
   additional ACP address; one address for each network on which join
   traffic is occuring.  The Join Proxy SHOULD do a GRASP M_NEG_SYN for
   each interface which they wish to relay traffic, as this allows the
   Registrar to do any static tunnel configuration that may be required.

C.2.  Automatic configuration of tunnels on Registrar

   The Join Proxy is expected to do a GRASP negotiation with the proxy
   for each Join Interface that it needs to relay traffic from.  This is
   to permit Registrars to configure the appropriate virtual interfaces
   before join traffic arrives.

   A Registrar serving a large number of interfaces may not wish to
   allocate resources to every interface at all times, but can instead
   dynamically allocate interfaces.  It can do this by monitoring IPIP
   traffic that arrives on it's ACP interface, and when packets arrive
   from new Join Proxys, it can dynamically configure virtual
   interfaces.

   A more sophisticated Registrar willing to modify the behaviour of
   it's TCP and UDP stack could note the IPIP traffic origination in the
   socket control block and make information available to the TCP layer
   (for HTTPS connections), or to the the application (for CoAP
   connections) via a proprietary extension to the socket API.

C.3.  Proxy Neighbor Discovery by Join Proxy

   The Join Proxy MUST answer neighbor discovery messages for the
   address given by the Registrar as being it's link-local address.  The
   Join Proxy must also advertise this address as the address to which
   to connect to when advertising it's existence.

   This proxy neighbor discovery means that the pledge will create TCP
   and UDP connections to the correct Registrar address.  This matters
   as the TCP and UDP pseudo-header checksum includes the destination
   address, and for the proxy to remain completely stateless, it must
   not be necessary for the checksum to be updated.

C.4.  Use of connected sockets; or IP_PKTINFO for CoAP on Registrar

   TCP connections on the registrar SHOULD properly capture the ifindex
   of the incoming connection into the socket structure.  This is normal
   IPv6 socket API processing.  The outgoing responses will go out on
   the same (virtual) interface by ifindex.

   When using UDP sockets with CoAP, the application will have to pay
   attention to the incoming ifindex on the socket.  Access to this
   information is available using the IP_PKTINFO auxiliary extension
   which is a standard part of the IPv6 sockets API.

   A registrar application could, after receipt of an initial CoAP
   message from the Pledge, create a connected UDP socket (including the
   ifindex information).  The kernel would then take care of accurate
   demultiplexing upon receive, and subsequent transmission to the
   correct interface.

C.5.  Use widest number of socket extension rather than virtual interface

   Some operating systems on which a Registrar need be implemented may
   find need for a virtual interface per Join Proxy to be problematic.
   There are other mechanism which can make be done. environments.

   If the IPIP decapsulator can mark the (SYN) packet inside the kernel
   with the address of the Join Proxy sending hardwareModuleName in the traffic, X.509 IDevID is populated then an
   interface per Join Proxy may not be needed.  The outgoing path need
   just pay attention to this extra information and add an appropriate
   IPIP header on outgoing.  A CoAP over UDP mechanism may need to
   expose this extra information to the application as the UDP sockets
   are often not connected, and the application will need to specify the
   outgoing path on each packet send.

   Such an additional socket mechanism has not been standardized.
   Terminating L2TP connections over IPsec transport mode suffers from
   the same challenges.

Appendix D.  To it
   SHOULD by default be deprecated: Consolidation remnants

   [[EDNOTE: As per working group feedback there were multiple instances
   where this document repeated itself.  To address this we have moved
   all text propagated to this appendix and restored only one copy of each
   normative discussion. the LDevID along with the
   hwSerialNum.  The next pass will reduce and delete EST server SHOULD support local policy concerning
   this
   appendix functionality.

   In networks using the BRSKI enrolled certificate to '0'; although some may be maintained in a design
   considerations appendix.]]

D.1.  Functional Overview

   Entities behave in an autonomic fashion.  They discover each other
   and autonomically bootstrap into a key infrastructure delineating authenticate the
   autonomic domain.
   ACP (Autonomic Control Plane), the EST attributes MUST include the
   "ACP information" field.  See [RFC7575]
   [I-D.ietf-anima-autonomic-control-plane] for more information.

   This section details the state machine and operational flow for each
   of the main three entities. details.

   The pledge, Registar MUST also confirm the domain (primarily resulting CSR is formatted as
   indicated before forwarding the request to a
   Registrar) and CA.  If the MASA service.

   A representative flow Registar is shown in Figure 2:

   +--------+         +---------+    +------------+     +------------+
   | Pledge |         | Circuit |    | Domain     |     | Vendor     |
   |        |         | Proxy   |    | Registrar  |     | Service    |
   |        |         |         |    |            |     | (Internet  |
   +--------+         +---------+    +------------+     +------------+
     |                     |                   |                    |
     |<-RFC3927 IPv4 adr   | Appendix A        |                    |
   or|<-RFC4862 IPv6 adr   |                   |                    |
     |                     |                   |                    |
     |-------------------->|                   |                    |
     | optional: mDNS query| Appendix B        |                    |
     | RFC6763/RFC6762     |                   |                    |
     |                     |                   |                    |
     |<--------------------|                   |                    |
     | GRASP M_FLOOD       |                   |                    |
     |   periodic broadcast|                   |                    |
     |                     |                   |                    |
     |<------------------->C<----------------->|                    |
     |              TLS via
   communicating with the CA using a protocol like full CMC which
   provides mechanisms to override the CSR attributes, then these
   mechanisms MAY be used even if the Circuit Proxy  |                    |
     |<--Registrar TLS server authentication---|                    |
   [PROVISIONAL accept of server cert]         |                    |
     P---X.509 client authentication---------->|                    |
     P                     |                   |                    |
     P---Request Voucher (include nonce)------>|                    |
     P                     |                   |                    |
     P                     |       /--->       |                    |
     P                     |       |      [accept device?]          |
     P                     |       |      [contact Vendor]          |
     P                     |       |           |--Pledge ID-------->|
     P                     |       |           |--Domain ID-------->|
     P                     |       |           |--optional:nonce--->|
     P                     |       |           |     [extract DomainID]
     P                     |       |           |                    |
     P                     |    optional:      |     [update audit log]
     P                     |       |can        |                    |
     P                     |       |occur      |                    |
     P                     |       |in         |                    |
     P                     |       |advance    |                    |
     P                     |       |           |                    |
     P                     |       |           |<-device audit log--|
     P                     |       |           |<- voucher ---------|
     P                     |       \---->      |                    |
     P                     |                   |                    |
     P                     |       [verify audit log ignores CSR Attribute
   guidance.

5.8.3.  EST Client Certificate Request

   The Pledge MUST request a new client certificate.  See RFC7030,
   section 4.2.

5.8.4.  Enrollment Status Telemetry

   For automated bootstrapping of devices the adminstrative elements
   providing bootstrapping also provide indications to the system
   administrators concerning device lifecycle status.  This might
   include information concerning attempted bootstrapping messages seen
   by the client, MASA provides logs and voucher]   |
     P                     |                   |                    |
     P<------voucher---------------------------|                    |
   [verify voucher ]       |                   |                    |
   [verify provisional cert|                   |                    |
     |                     |                   |                    |
     |<--------------------------------------->|                    |
     | Continue with RFC7030 status of credential
   enrollment.  The EST protocol assumes an end user and therefore does
   not include a final success indication back to the server.  This is
   insufficient for automated use cases.

   To indicate successful enrollment        |                    |
     | the client SHOULD re-negotiate the
   EST TLS session using now bidirectionally authenticated |                    |
     | the newly obtained credentials.  This occurs by
   the client initiating a new TLS session.        |                   |                    |
     |                     |                   |                    |
     |                     |                   |                    |
     |                     |                   |                    |

   Figure 2

   [[UNRESOLVED:need to restore some functional overview section ClientHello message on the existing
   TLS connection.  The client MAY simply close the old TLS session and
   start a new one.  The server MUST support either model.

   In the case of a FAIL the Reason string indicates why the most recent
   enrollment failed.  The SubjectKeyIdentifier field MUST be included
   if the enrollment attempt was for all
   these diagrams]]In order to obtain a Voucher keypair that is locally known to
   the client.  If EST /serverkeygen was used and associated logs failed then the field
   is omitted from the status telemetry.

   In the case of a
   Registrar contacts SUCCESS the MASA service Service using REST calls:

              +-----------+ +----------+ +-----------+ +----------+
              | New       | | Circuit  | |           | |          |
              | Entity    | | Proxy    | | Registrar | | Vendor   |
              |           | |          | |           | |          |
              ++----------+ +--+-------+ +-----+-----+ +--------+-+
               |               |               |                |
               |               |               |                |
               |   TLS hello   |  TLS hello    |                |
   Establish   +---------------C--------------->                |
   TLS         |               |               |                |
   connection  |               | Server Cert   |                |
               <---------------C---------------+                |
               | Client Cert   |               |                |
               +---------------C--------------->                |
               |               |               |                | Reason string is omitted.  The
   SubjectKeyIdentifier is included so that the server can record the
   successful certificate distribution.

   Status media type: application/json

   The client HTTP POSTs the following to the server at the new EST well
   known URI /enrollstatus.

   {
     "version":"1",
     "Status":TRUE /* TRUE=Success, FALSE=Fail"
     "Reason":"Informative human readable message"
     "reason-context": "Additional information"
   }

   The server SHOULD respond with an HTTP REST   | POST /requestvoucher          |                |
   Data        +--------------------nonce------>                |
               |               .               | /requestvoucher|
               |               .               +---------------->
               |                               <----------------+
               |                               | /requestlog    |
               |                               +---------------->
               |            voucher            <----------------+
               <-------------------------------+                |
               | (optional config information) |                |
               |               .               |                |
               |               .               |                |

   Figure 8

   In some use cases 200 but MAY simply fail with
   an HTTP 404 error.

   Within the Registrar may need server logs the server MUST capture if this message was
   received over an TLS session with a matching client certificate.
   This allows for clients that wish to contact minimize their crypto operations
   to simply POST this response without renegotiating the Vendor in
   advanced, TLS session -
   at the cost of the server not being able to accurately verify that
   enrollment was truly successful.

5.8.5.  EST over CoAP

   This document describes extensions to EST for example when the target network purposes of
   bootstrapping of remote key infrastructures.  Bootstrapping is air-gapped.
   relevant for CoAP enrollment discussions as well.  The
   nonceless request format defintion of
   EST and BRSKI over CoAP is provided not discussed within this document beyond
   ensuring proxy support for CoAP operations.  Instead it is
   anticipated that a definition of CoAP mappings will occur in
   subsequent documents such as [I-D.vanderstok-ace-coap-est] and that
   CoAP mappings for BRSKI will be discussed either there or in future
   work.

6.  Reduced security operational modes

   A common requirement of bootstrapping is to support less secure
   operational modes for support specific use cases.  The following
   sections detail specific ways that the Pledge, Registrar and MASA can
   be configured to run in a less secure mode for this and the resulting flow
   is slightly different.  The security differences associated with not
   knowing the nonce are discussed below:

              +-----------+ +----------+ +-----------+ +----------+ indicated reasons.

6.1.  Trust Model

   +--------+         +---------+    +------------+     +------------+
   | New Pledge |         | Circuit |    | Domain     |     | Vendor     |
   | Entity        |         | Proxy   |    | Registrar  |     | Vendor   |
              |           | |          | |           | |          |
              ++----------+ +--+-------+ +-----+-----+ +--------+-+
               |               |               |                |
               |               |               |                |
               |               |               | /requestvoucher|
               |               |  (nonce       +---------------->
               |               |  unknown)     <----------------+
               |               |               | /requestlog    |
               |               |               +---------------->
               |               |               <----------------+
               |   TLS hello   |  TLS hello    |                |
   Establish   +---------------C--------------->                |
   TLS         |               |               |                |
   connection  |               | Server Cert   |                |
               <---------------C---------------+                |
               | Client Cert   |               |                |
               |               |               |                |
   HTTP REST   | POST /requestvoucher          |                |
   Data        +----------------------nonce---->   (discard     |
               |            voucher            |   nonce)       |
               <-------------------------------+                | Service    | (optional config information)
   |        |         |               .         |    |            |               .     | (Internet  |
   +--------+         +---------+    +------------+     +------------+

   Figure 9

D.1.1.  Behavior 10

   Pledge:  The Pledge could be compromised and providing an attack
      vector for malware.  The entity is trusted to only imprint using
      secure methods described in this document.  Additional endpoint
      assessment techniques are RECOMMENDED but are out-of-scope of this
      document.

   Proxy:  Provides proxy functionalities but is not involved in
      security considerations.

   Registrar:  When interacting with a MASA server a Registrar makes all
      decisions.  When Ownership Vouchers are involved a Registrar is
      only a conduit and all security decisions are made on the vendor
      service.

   Vendor Service, MASA:  This form of vendor service is trusted to
      accurately log all claim attempts and to provide authoritative log
      information to Registrars.  The MASA does not know which devices
      are associated with which domains.  These claims could be
      strengthened by using cryptographic log techniques to provide
      append only, cryptographic assured, publicly auditable logs.
      Current text provides only for a trusted vendor.

   Vendor Service, Ownership Validation:  This form of vendor service is
      trusted to accurately know which device is owned by which domain.

6.2.  Pledge

   A pledge that has not yet been bootstrapped attempts security reductions

   The Pledge can choose to find a local
   domain accept vouchers using less secure methods.
   These methods enable offline and join it.  A pledge [[RESOLVED:MUST NOT]] automatically
   initiate bootstrapping if it has already been configured or is in emergency (touch based) deployment
   use cases:

   1.  The Pledge MUST accept nonceless vouchers.  This allows for
       offline use cases.  Logging and validity periods address the
   process of being configured.

   States
       inherent security considerations of a pledge are as follows:

                +--------------+
                |   Factory    |
                |   default    |
                +------+-------+
                       |
                +------v-------+
                |  Discover    |
   +------------>              |
   |            +------+-------+
   |                   |
   |            +------v-------+
   |            |  Identity    |
   ^------------+              |
   | rejected   +------+-------+
   |                   |
   |            +------v-------+
   |            | Request      |
   |            | Join         |
   |            +------+-------+
   |                   |
   |            +------v-------+
   |            |  Imprint     |   Optional
   ^------------+              <--+Manual input (Appendix C)
   | Bad Vendor +------+-------+
   | response          |
   |            +------v-------+
   |            |  Enroll      |
   ^------------+              |
   | Enroll     +------+-------+
   | Failure           |
   |            +------v-------+
   |            |  Enrolled    |
   ^------------+              |
    Factory     +--------------+
    reset

   Figure 3

   State descriptions supporting these use cases.

   2.  The Pledge MAY support "trust on first use" for the pledge are physical
       interfaces such as follows:

   1.  Discover a communication channel to local console port or physical user
       interface but MUST NOT support "trust on first use" on network
       interfaces.  This is because "trust on first use" permanently
       degrades the security for all use cases.

   3.  The Pledge MAY have an operational mode where it skips Voucher
       validation one time.  For example if a Registrar.

   2.  Identify itself. physical button is
       depressed during the bootstrapping operation.  This can be useful
       if the vendor service is done by presenting an X.509 IDevID
       credential unavailable.  This behavior SHOULD be
       available via local configuration or physical presence methods to the discovered
       ensure new entities can always be deployed even when autonomic
       methods fail.  This allows for unsecured imprint.

   It is RECOMMENDED that "trust on first use" or skipping voucher
   validation only be available if hardware assisted Network Endpoint
   Assessment [RFC5209] is supported.  This recommendation ensures that
   domain network monitoring can detect innappropriate use of offline or
   emergency deployment procedures.

6.3.  Registrar (via the Proxy) in a TLS
       handshake.  (The security reductions

   A Registrar credentials are only provisionally
       accepted at this time).

   3.  Requests can choose to Join accept devices using less secure methods.
   These methods are acceptable when low security models are needed, as
   the discovered Registrar.  A unique nonce
       [[RESOLVED:can be]] included ensuring that any responses can security decisions are being made by the local administrator, but
   they MUST NOT be
       associated with this the default behavior:

   1.  A registrar MAY choose to accept all devices, or all devices of a
       particular bootstrapping attempt.

   4.  Imprint on type, at the Registrar. administrator's discretion.  This requires verification could
       occur when informing all Registrars of the
       vendor service provided voucher. unique identifiers of new
       entities might be operationally difficult.

   2.  A voucher contains sufficient
       information for the Pledge registrar MAY choose to complete authentication of accept devices that claim a
       Registrar.  (It enables unique
       identity without the Pledge to finish authentication benefit of authenticating that claimed
       identity.  This could occur when the Registrar TLS server certificate).

   5.  Enroll.  By accepting Pledge does not include an
       X.509 IDevID factory installed credential.  New Entities without
       an X.509 IDevID credential MAY form the domain specific information from a
       Registrar, and by obtaining a domain certificate from a Registrar Section 5.2 request using a standard enrollment protocol, e.g.  Enrollment over
       Secure Transport (EST) [RFC7030].

   6.  The Pledge is now a member of, and can be managed by,
       the domain
       and will only repeat Section 5.4 format to ensure the discovery aspects of bootstrapping if it Pledge's serial number
       information is returned provided to factory default settings.

   The following sections describe each of these steps in more detail.

D.1.1.1.  Discovery

   [[RESOLVED:TEXT moved up into above]]

D.1.1.2.  Identity

   The Pledge identifies itself during the communication protocol
   handshake.  If Registar (this includes the client identity is rejected (that is, IDevID
       AuthorityKeyIdentifier value which would be statically configured
       on the Pledge).  The Pledge MAY refuse to provide a TLS
   handshake does client
       certificate (as one is not complete) the available).  The Pledge repeats the Identity process
   using the next proxy SHOULD support
       HTTP-based or discovery method available.

   [[RESOLVED: need normative statement certificate-less TLS authentication as described in protocol section]] The
   bootstrapping protocol server is
       EST RFC7030 section 3.3.2.  A Registrar MUST NOT accept
       unauthenticated New Entities unless it has been configured to do
       so by an administrator that has verified that only expected new
       entities can communicate with a Registrar (presumably via a
       physically secured perimeter).

   3.  A Registrar MAY request nonce-less Vouchers from the MASA service
       (by not initially authenticated.  Thus including a nonce in the request).  These Vouchers can
       then be transmitted to the connection is provisional Registrar and all data received is untrusted stored until sufficiently validated even though it is over a TLS connection. they are
       needed during bootstrapping operations.  This is aligned with the existing provisional mode of EST [RFC7030]
   during s4.1.1 "Bootstrap Distribution of CA Certificates".  See
   Section 3.4 for more information about when the TLS connection
   authentication use cases
       where target network is completed.

   [[RESOLVED:]]All security associations established are between the
   new device and the Bootstrapping server regardless of proxy
   operations.

D.1.1.2.1.  Concurrent attempts to join

   [[RESOLVED: protected by dropping this text. the "priority mechanism" is
   unspecified thus any discussion is unclear.  Not only that once an
   initial request is sent to the registrar air gap and therefore can
       not contact the question of multiple MASA interactions has already occurred.  Nothing breaks if
   implementations do this.  I've added text to the security
   considerations indicating the end result (MASA entries that might be
   ignored by the device but which confuse the end administrator)]] The service during Pledge deployment.

   4.  A registrar MAY attempt multiple mechanisms concurrently, but if it does
   so, it MUST wait ignore unrecognized nonce-less log entries.  This
       could occur when used equipment is purchased with a valid history
       being deployed in air gap networks that required permanent
       Vouchers.

6.4.  MASA security reductions

   Lower security modes chosen by the provisional state until MASA service effect all mechanisms have
   either succeeded or failed, and then MUST proceed with device
   deployments unless bound to the highest
   priority mechanism specific device identities.  In which has succeed.  To proceed beyond this point,
   specifically,
   case these modes can be provided as additional features for specific
   customers.  The MASA service can choose to provide a nonce, could result run in the MASA
   gratuitously auditing a connection.

D.1.1.3.  Request Join

   The Pledge POSTs less secure modes
   by:

   1.  Not enforcing that a request to join the domain to nonce is in the Bootstrapping
   server. Voucher.  This request contains a Pledge generated nonce results in
       distribution of Voucher that never expires and informs in effect makes
       the Bootstrapping server which imprint methods Domain an always trusted entity to the Pledge will
   accept.

   The nonce ensures during any
       subsequent bootstrapping attempts.  That this occurred is
       captured in the Pledge can verify log information so that responses are specific
   to this bootstrapping attempt.  This minimizes the use of global time
   and provides a substantial benefit for devices without Registrar can make
       appropriate security decisions when a valid clock.

D.1.1.3.1.  Redirects during Pledge joins the Join Process

   [[RESOVED via current root protocol discussion. reference to
   mdnsmethods Domain.
       This is dropped]] EST [RFC7030] describes situations useful to support use cases where Registrars might not be
       online during actual device deployment.  Because this results in
       long lived Voucher and does not require the
   bootstrapping server MAY redirect proof that the client to an alternate server
   via a 3xx status code.  Such redirects MAY be device
       is online this is only accepted if when the pledge
   has used Registrar is
       authenticated by the methods described in Appendix B, MASA server and authorized to provide this
       functionality.  The MASA server is RECOMMENDED to use this
       functionality only in combination concert with an
   implicit trust anchor.  Redirects during enhanced level of ownership
       tracking (out-of-scope).  If the provisional Pledge device is known to have a
       real-time-clock that is set from the factory use of a voucher
       validity period are
   otherwise unstrusted, is RECOMMENDED.

   2.  Not verifying ownership before responding with an Voucher.  This
       is expected to be a common operational model because doing so
       relieves the vendor providing MASA services from having to track
       ownership during shipping and supply chain and MUST cause allows for a failure.

D.1.1.4.  Imprint

   The Pledge validates the voucher and accepts the Registrar ID.  The
   provisional TLS connection is validated using the very
       low overhead MASA service.  A Registrar ID from
   the voucher.

D.1.1.5.  Lack of realtime clock APPENDIX

   [[RESOVED: entire section promoted back into the main text]]
   Many devices when bootstrapping do not have knowledge of uses the current
   time.  Mechanisms like Network Time Protocols can not be secured
   until bootstrapping is complete.  Therefore bootstrapping is defined
   in audit log
       information as a method defense in depth strategy to ensure that this
       does not require knowledge of the current time.

   Unfortunately there are moments during bootstrapping occur unexpectedly (for example when
   certificates are verified, such as during purchasing new
       equipment the TLS handshake, where
   validity periods are confirmed.  This paradoxical "catch-22" Registrar would throw an error if any audit log
       information is
   resolved by reported).  The MASA should verify the Pledge maintaining 'prior-
       signed-voucher' information for Pledge's that support that
       functionality.  This provides a concept of the current "window"
   of presumed time validity proof-of-proximity check that is continually refined throughout
       reduces the
   bootstrapping process as follows:

   o  Initially need for ownership verification.

7.  IANA Considerations

   This document requests the Pledge does not know following Parameter Values for the current time. "smime-
   type" Parameters:

   o  During Pledge authentiation by  voucher-request

   o  voucher

7.1.  PKIX Registry

   IANA is requested to register the Registrar following:

   This document requests a number for id-mod-MASAURLExtn2016(TBD) from
   the pkix(7) id-mod(0) Registry.  [[EDNOTE: fix names]]

   This document requests a number from the id-pe registry for id-pe-
   masa-url.  XXX

7.2.  MIME

   Type name:

   Subtype name:

   Required parameters:

   Optional parameters:

   Encoding considerations:

   Security considerations:

   Interoperability considerations:

   Published specification:

   Applications that use this media type:

   Fragment identifier considerations:

   Additional information:

   Deprecated alias names for this type:

        Magic number(s):

        File extension(s):

        Macintosh file type code(s):

      Person and email address to contact for further information:

   Intended usage:  LIMITED USED

   Restrictions on usage:

   Author:

   Change controller:

   Provisional registration? (standards tree only):

7.3.  Voucher Status Telemetry

   IANA is requested to create a realtime clock registry entitled: _Voucher Status
   Telemetry Attributes_.  New items can be used by the Registrar.  This bullet expands on a closely
      related issue regarding Pledge lifetimes.  RFC5280 indicates that
      long lived Pledge certifiates "SHOULD be assigned the
      GeneralizedTime value of 99991231235959Z" [RFC7030] so the
      Registrar MUST support such lifetimes and SHOULD support ignoring
      Pledge lifetimes if they did not follow added using the RFC5280
      recommendations.

   o
   Specification Required.  The Pledge authenticates the voucher presented following items are to it.  During this
      authentication the Pledge ignores certificate lifetimes (by
      necessity because it does not have a clock).  The voucher itself
      SHOULD contain the nonce included be in the original request which
      proves initial
   registration, with this document as the voucher is fresh. reference:

   o  Once the voucher is accepted the validity period of  version

   o  Status

   o  Reason

   o  reason-context

8.  Security Considerations

   There are uses cases where the
      domainCAcert in MASA could be unavailable or
   uncooperative to the voucher (see Section 3.4) now serves as Registrar.  They include planned and unplanned
   network partitions, changes to MASA policy, or other instances where
   MASA policy rejects a
      valid time window.  Any subsequent certificate validity periods
      checked during RFC5280 path validation MUST occur within this
      window.

   o  When accepting claim.  These introduce an enrollment certificate operational risk to
   the validity period
      within Registrar owner that MASA/vendor behavior might limit the new certificate is assumed ability
   to re-boostrap a Pledge device.  For example this might be valid an issue
   during disaster recovery.  This risk can be mitigated by the Pledge.
      The Pledge is now willing Registrars
   that request and maintain long term copies of "nonceless" Vouchers.
   In that way they are guaranteed to be able to use this credential repeat bootstrapping
   for client
      authentication.

D.1.1.6.  Enrollment

   As the final step their devices.

   The issuance of bootstrapping nonceless vouchers themselves create a security
   concern.  If the Registrar helps to issue of a previous domain specific credential to the Pledge.  For simplicity in this
   document, can intercept
   protocol communications then it can use a Registrar primarily facilitates issuing previously issued nonceless
   voucher to establish management control of a credential pledge device even after
   having sold it.  This risk is mitigated by
   acting as an RFC5280 Registration Authority for recording the Domain
   Certification Authority.

   Enrollment proceeds as described in [RFC7030].  Authentication issuance of
   such vouchers in the
   EST server MASA audit log that is done using verified by the Voucher rather than
   subsequent Registrar.  This reduces the methods defined
   in EST.

   [[RESOLVED: moved to protocol discussion]]Once resale value of the Voucher is
   received, as specified equipment
   because future owners will detect the lowered security inherent in this document,
   the client has sufficient
   information to leverage existence of a nonceless voucher that would be trusted by their
   Pledge.  This reflects a balance between partition resistant recovery
   and security of future bootstrapping.  Registrars take the existing communication channel with Pledge's
   audit history into account when applying policy to new devices.

   The MASA server is exposed to DoS attacks wherein attackers claim an
   unbounded number of devices.  Ensuring a Registrar is representative
   of a valid vendor customer, even without validating ownership of
   specific Pledge devices, helps to continue an EST RFC7030 enrollment.  Enrollment picks up
   at RFC7030 section 4.1.1.  bootstrapping where the Voucher provides
   the "out-of-band" CA certificate fingerprint (in this case the full
   CA certificate) such that mitigate this.  Pledge signatures
   on the client can now complete initial voucher request, as forwarded by the TLS server
   authentication.  At Registrar in the
   prior-signed-voucher field, significantly reduce this point risk by
   ensuring the client continues with EST
   enrollment operations including "CA Certificates Request", "CSR
   Attributes" MASA can confirm proximity between the Pledge and "Client Certificate Request" or "Server-Side Key
   Generation".

   [[RESOLVED: included into EST discussion]]For the purposes of
   creating
   Registrar making the ANIMA Autonomic Control Plane, request.  This mechanism is optional to allow
   for constrained devices.

   It is possible for an attacker to request a voucher from the contents of MASA
   service directly after the new
   certificate MUST be carefully specified.
   [I-D.ietf-anima-autonomic-control-plane] section 5.1.1 contains
   details.  The real Registrar MUST provide obtains an audit log.  If
   the attacker could also force the correct ACP information bootstrapping protocol to populate the subjectAltName / rfc822Name field in reset
   there is a theoretical opportunity for the "CSR
   Attributes" step.

D.1.1.7.  Being Managed

   [[RESOLVED: by slight change to introduction text.]] Functionality attacker to
   provide generic "configuration" information is supported.  The
   parsing of this data and any subsequent use their
   voucher to take control of the data, for example
   communications with a Network Management System is out of scope Pledge but
   is expected then proceed to occur after bootstrapping enrollment is complete.
   This ensures that all communications enroll with management systems which
   can divulge local security information (e.g. network topology or raw
   key material) is secured using
   the local credentials issued during
   enrollment.

   The Pledge uses bootstrapping to join only one target domain.  Management by
   multiple domains is out-of-scope of bootstrapping.  After the  Possible prevention mechanisms include:

   o  Per device
   has successfully joined a domain and is being managed it is plausible
   that the domain can insert credentials for other domains depending rate limits on the device capabilities.

   See Appendix D.1.5.

D.1.2.  Behavior of a Join Proxy MASA service ensure such timing
      attacks are difficult.

   o  The role of Registrar can repeat the Proxy request for audit log information at
      some time after bootstrapping is to complete.

   To facilitate communications.  The Proxy
   forwards packets between logging and administrative oversight the Pledge and a Registrar that has been
   configured reports
   on the Proxy.

   [[UNRESOLVED: since proxy behavior is not visible we can limit
   ourselves Voucher parsing status to discussion of what the protocol does to enable/faciliate
   a theoretical proxy]]The Proxy does not terminate Registrar.  In the TLS handshake.

   [[UNRESOLVED: case of a failure
   this information is an anima architecture requirement to use BRSKI?
   move informative to there?]] A Proxy a potentially malicious Registar
   but this is always assumed even if it RECOMMENDED anyway because of the operational benefits of
   an informed administrator in cases where the failure is directly
   integrated into a Registrar.  (In indicative of
   a completely autonomic network, the
   Registrar MUST provide proxy functionality so problem.

   To facilitate truely limited clients EST RFC7030 section 3.3.2
   requirements that it can be
   discovered, and the network can grow concentrically around the
   Registrar)

   As client MUST support a result of the Proxy Discovery process client authentication
   model have been reduced in section
   Appendix D.1.1.1, the port number exposed by the proxy does not need
   to be well known, or require an IANA allocation.

   If the Proxy joins an Autonomic Control Plane
   ([I-D.ietf-anima-autonomic-control-plane]) it SHOULD use Autonomic
   Control Plane secured GRASP ([I-D.ietf-anima-grasp]) Section 6 to discovery a statement that the
   Registrar address and port.  As part of the discovery process, the
   proxy mechanism (Circuit Proxy vs IPIP encapsulation) is agreed "MAY" choose to
   between the Registrar and Join Proxy.

   For the IPIP encapsulation methods, accept devices that fail cryptographic
   authentication.  This reflects current (poor) practices in shipping
   devices without a cryptographic identity that are NOT RECOMMENDED.

   During the port announced by provisional period of the Proxy connection all HTTP header and
   content data MUST be the same treated as on the registrar in order for the proxy to remain
   stateless.

   In order untrusted data.  HTTP libraries are
   regularly exposed to permit the proxy functionality non-secured HTTP traffic: mature libraries
   should not have any problems.

   Pledge's might chose to be implemented on the
   maximum variety of devices the chosen mechanism SHOULD use the
   minimum amount of state on the proxy device.  While many devices engage in
   the ANIMA target space protocol operations with multiple
   discovered Registrars in parallel.  As noted above they will only do
   so with distinct nonce values, but the end result could be rather large routers, multple
   voucher's issued from the proxy
   function is likely MASA if all registrars attempt to be implemented in claim the control plane CPU of such
   device.  This is not a device, with available capabilities for failure and the proxy function similar Pledge choses whichever
   voucher to many class 2 IoT devices. accept based on internal logic.  The document [I-D.richardson-anima-state-for-joinrouter] provides a
   more extensive analysis of Registrar's verifying
   log information will see multiple entries and take this into account
   for their analytics purposes.

8.1.  Freshness in Voucher Requests

   A concern has been raised that the voucher request produced by the
   Pledge should contain some content (a nonce) from the alternative proxy methods.

D.1.2.1.  CoAP connection to Registrar

   [[RESOLVED:this section thus removed]]The CoAP mechanism was
   depreciated.

D.1.2.2.  HTTPS proxy connection to Registrar

   The proxy SHOULD also provide one of: an IPIP encapsulation of HTTP
   traffic on TCP port TBD and/
   or MASA in order for those actors to verify that the registrar, or voucher request
   is fresh.

   There are a TCP circuit proxy that
   connects number of operational problems with getting a nonce from
   the Pledge MASA to a Registrar.

   When the Proxy provides a circuit proxy pledge.  It is somewhat easier to collect a Registrar random
   value from the Registrar
   MUST accept HTTPS connections.

   When Registrar, but as the Proxy provides Registrar is not yet vouched
   for, such a stateless IPIP encapsulation Registrar nonce has little value.  There are privacy and
   logistical challenges to addressing these operational issues, so if
   such a
   Registrar, then the Registrar will thing were to be considered, it would have to perform IPIP
   decapsulation, remembering provide some
   clear value.  This section examines the originating outer IPIP source address
   in order to qualify impacts of not having a fresh
   voucher request from the inner link-local address.  This is pledge.

   Because the Registrar authenticates the Pledge a kind of
   encapsulation and processing which full Man-in-the-
   Middle attack is similar in many ways to how
   mobile IP works.

   Being able to connect not possible, despite the provisional TLS
   authentication by the Pledge (see Section 5).  Instead we examine the
   case of a TCP (HTTP) fake Registrar (Rm) that communicates with the Pledge in
   parallel or UDP (CoAP) socket to a link-
   local address in close time proximity with an encapsulated IPIP header requires API
   extensions beyond [RFC3542] for UDP use, and requires the intended Registrar.
   (This scenario is intentionally supported as described in
   Section 4.1).

   The fake Registrar (Rm) can obtain a form of
   connection latching (see section 4.1 of [RFC5386] and all of
   [RFC5660], except voucher signed by the MASA
   either directly or through arbitrary intermediaries.  Assuming that
   the MASA accepts the voucher request (either because Rm is
   collaborating with a simple IPIP tunnel legitimate Registrar according to supply chain
   information, or because the MASA is used rather than an
   IPsec tunnel).

D.1.3.  Behavior of in audit-log only mode), then a
   voucher linking the pledge to the Registrar

   A Registrar listens for Pledges and determines if they can join Rm is issued.

   Such a voucher, when passed back to the Pledge, would link the
   domain.  A pledge
   to Registrar obtains a Voucher from the MASA service Rm, and
   delivers them to would permit the Pledge as well as facilitating enrollment with
   the domain PKI.

   [[RESOLVED: moved to discovery discussion]] A Registrar is typically
   configured manually.  When end the Registrar joins an Autonomic Control
   Plane ([I-D.ietf-anima-autonomic-control-plane]) provisional
   state.  It now trusts Rm and, if it MUST respond has any security vulnerabilities
   leveragable by an Rm with full administrative control, can be assumed
   to
   GRASP ([I-D.ietf-anima-grasp]) M_DISCOVERY message.  See
   Section 3.1.2

   Registrar behavior be a threat against the intended Registrar.

   This flow is as follows:

   Contacted mitigated by Pledge
           +
           |
   +-------v----------+
   | Entity           | fail?
   | Authentication   +---------+
   +-------+----------+         |
           |                    |
   +-------v----------+         |
   | Entity           | fail?   |
   | Authorization    +--------->
   +-------+----------+         |
           |                    |
   +-------v----------+         |
   | Claiming the     | fail?   |
   | Entity           +--------->
   +-------+----------+         |
           |                    |
   +-------v----------+         |
   | Log Verification | fail?   |
   |                  +--------->
   +-------+----------+         |
           |                    |
   +-------v----------+    +----v-------+
   | Forward          |    |            |
   | Voucher          |    | Reject     |
   | to intended Registar verifying the Pledge    |    | Device     |
   |                  |    |            |
   +------------------+    +------------+

   Figure 4

D.1.3.1.  Pledge Authentication

   The applicable authentication methods detailed in EST [RFC7030] are:

   o  [[RESOLVED:pointed out audit
   logs available from the MASA as described in protocol details]]the use of an X.509
      IDevID credential during Section 5.7.  Rm might
   chose to wait until after the TLS client authentication,

   o  or intended Registrar completes the use of a secret that is transmitted out of band between
   authorization process before submitting the
      Pledge and a Registrar (this use case is not autonomic). now-stale voucher
   request.  The Rm would need to remove the Pledge's nonce.

   In order to validate successfully use the X.509 IDevID credential a Registrar
   maintains a database of vendor trust anchors (e.g. vendor root
   certificates or keyIdentifiers for vendor root public keys).  For
   user interface purposes this database can be mapped resulting "stale voucher" Rm would
   have to colloquial
   vendor names.  Registrars can be shipped with attack the Pledge and return it to a bootstrapping enabled
   state.  This would require wiping the trust anchors Pledge of current configuration
   and triggering a
   significant number re-bootstrapping of third-party vendors within the target market.

D.1.3.2.  Pledge Authorization

   [[UNRESOLVED: this Pledge.  This is referenced above as how no more
   likely than simply taking control of the MASA does
   authorization.  That Pledge directly but if this
   is incorrect]]

   In a fully automated network all devices must be securely identified
   and authorized to join consideration the domain.

   A Registrar accepts or declines a request target network is RECOMMENDED to join the domain, based
   on take the authenticated identity presented.  Automated acceptance
   criteria include:
   following steps:

   o  allow any device of a specific type (as determined  Ongoing network monitoring for unexpected bootstrapping attempts
      by the X.509
      IDevID), Pledges.

   o  allow  Retreival and examination of MASA log information upon the
      occurance of any device from a specific vendor (as determined by such unexpected events.  Rm will be listed in the
      X.509 IDevID),

   o  allow a specific device from a vendor (as determined by
      logs.

9.  Acknowledgements

   We would like to thank the X.509
      IDevID) against a domain white list.  (The mechanism various reviewers for their input, in
   particular Brian Carpenter, Toerless Eckert, Fuyu Eleven, Eliot Lear,
   Sergey Kasatkin, Markus Stenberg, and Peter van der Stok

10.  References

10.1.  Normative References

   [I-D.ietf-anima-autonomic-control-plane]
              Behringer, M., Eckert, T., and S. Bjarnason, "An Autonomic
              Control Plane (ACP)", draft-ietf-anima-autonomic-control-
              plane-10 (work in progress), September 2017.

   [I-D.ietf-anima-voucher]
              Watsen, K., Richardson, M., Pritikin, M., and T. Eckert,
              "Voucher Profile for Bootstrapping Protocols", draft-ietf-
              anima-voucher-05 (work in progress), August 2017.

   [I-D.vanderstok-ace-coap-est]
              Kumar, S., Stok, P., Kampanakis, P., Furuhed, M., and S.
              Raza, "EST over secure CoAP (EST-coaps)", draft-
              vanderstok-ace-coap-est-02 (work in progress), June 2017.

   [IDevID]   IEEE Standard, "IEEE 802.1AR Secure Device Identifier",
              December 2009, <http://standards.ieee.org/findstds/
              standard/802.1AR-2009.html>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3542]  Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei,
              "Advanced Sockets Application Program Interface (API) for checking
      a shared white list potentially used by multiple Registrars is out
              IPv6", RFC 3542, DOI 10.17487/RFC3542, May 2003,
              <https://www.rfc-editor.org/info/rfc3542>.

   [RFC3748]  Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
              Levkowetz, Ed., "Extensible Authentication Protocol
              (EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004,
              <https://www.rfc-editor.org/info/rfc3748>.

   [RFC3927]  Cheshire, S., Aboba, B., and E. Guttman, "Dynamic
              Configuration of scope).

   [[RESOLVED: this looks like good text to include in above]]To look
   the Pledge up in a domain white list a consistent method IPv4 Link-Local Addresses", RFC 3927,
              DOI 10.17487/RFC3927, May 2005,
              <https://www.rfc-editor.org/info/rfc3927>.

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862,
              DOI 10.17487/RFC4862, September 2007,
              <https://www.rfc-editor.org/info/rfc4862>.

   [RFC4941]  Narten, T., Draves, R., and S. Krishnan, "Privacy
              Extensions for
   extracting device identity from the Stateless Address Autoconfiguration in
              IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,
              <https://www.rfc-editor.org/info/rfc4941>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <https://www.rfc-editor.org/info/rfc5246>.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 certificate is required.
   RFC6125 describes Domain-Based Application Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
              <https://www.rfc-editor.org/info/rfc5280>.

   [RFC5386]  Williams, N. and M. Richardson, "Better-Than-Nothing
              Security: An Unauthenticated Mode of IPsec", RFC 5386,
              DOI 10.17487/RFC5386, November 2008,
              <https://www.rfc-editor.org/info/rfc5386>.

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
              RFC 5652, DOI 10.17487/RFC5652, September 2009,
              <https://www.rfc-editor.org/info/rfc5652>.

   [RFC5660]  Williams, N., "IPsec Channels: Connection Latching",
              RFC 5660, DOI 10.17487/RFC5660, October 2009,
              <https://www.rfc-editor.org/info/rfc5660>.

   [RFC6762]  Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
              DOI 10.17487/RFC6762, February 2013,
              <https://www.rfc-editor.org/info/rfc6762>.

   [RFC6763]  Cheshire, S. and M. Krochmal, "DNS-Based Service identity but here
   we require Vendor Device-Based identity.  The subject field's DN
   encoding MUST include the "serialNumber" attribute with the device's
   unique serial number.  In the language of RFC6125 this provides for a
   SERIALNUM-ID category of identifier that can be included in a
   certificate
              Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
              <https://www.rfc-editor.org/info/rfc6763>.

   [RFC7030]  Pritikin, M., Ed., Yee, P., Ed., and therefore that can also be used D. Harkins, Ed.,
              "Enrollment over Secure Transport", RFC 7030,
              DOI 10.17487/RFC7030, October 2013,
              <https://www.rfc-editor.org/info/rfc7030>.

   [RFC7159]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
              2014, <https://www.rfc-editor.org/info/rfc7159>.

   [RFC7228]  Bormann, C., Ersue, M., and A. Keranen, "Terminology for matching
   purposes.  The SERIALNUM-ID whitelist is collated according to vendor
   trust anchor since serial numbers are not globally unique.

   [[RESOLVED: into log request]]The Registrar MUST use the vendor
   provided MASA service to verify that the device's history log does
   not include unexpected Registrars.  If a device had previously
   registered
              Constrained-Node Networks", RFC 7228,
              DOI 10.17487/RFC7228, May 2014,
              <https://www.rfc-editor.org/info/rfc7228>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [RFC7951]  Lhotka, L., "JSON Encoding of Data Modeled with another domain, YANG",
              RFC 7951, DOI 10.17487/RFC7951, August 2016,
              <https://www.rfc-editor.org/info/rfc7951>.

10.2.  Informative References

   [I-D.behringer-homenet-trust-bootstrap]
              Behringer, M., Pritikin, M., and S. Bjarnason,
              "Bootstrapping Trust on a Registrar of that domain would show Homenet", draft-behringer-
              homenet-trust-bootstrap-02 (work in the log.

   [[RESOLVED: est integration section used 'SHOULD']]The authorization
   performed during BRSKI MAY be used for EST enrollment requests by
   proceeding with EST enrollment using the authenticated progress), February
              2014.

   [I-D.ietf-anima-grasp]
              Bormann, C., Carpenter, B., and authorized
   TLS connection.  This minimizes the number of cryptographic B. Liu, "A Generic
              Autonomic Signaling Protocol (GRASP)", draft-ietf-anima-
              grasp-15 (work in progress), July 2017.

   [I-D.ietf-netconf-zerotouch]
              Watsen, K., Abrahamsson, M., and
   protocol operations necessary to complete bootstrapping of the local
   key infrastructure.

D.1.3.3.  Claiming the Pledge

   Claiming an pledge establishes an audit log at the MASA server I. Farrer, "Zero Touch
              Provisioning for NETCONF or RESTCONF based Management",
              draft-ietf-netconf-zerotouch-17 (work in progress),
              September 2017.

   [I-D.ietf-opsawg-mud]
              Lear, E., Droms, R., and
   provides a Registrar with proof, D. Romascanu, "Manufacturer Usage
              Description Specification", draft-ietf-opsawg-mud-12 (work
              in the form of the Voucher, that the
   log entry has been inserted.  As indicated progress), October 2017.

   [I-D.richardson-anima-state-for-joinrouter]
              Richardson, M., "Considerations for stateful vs stateless
              join router in Appendix D.1.1.4 a
   Pledge will only proceed with bootstrapping if a Voucher has been
   received.  The Pledge therefore enforces that bootstrapping only
   occurs if the claim has been logged.  There is no requirement ANIMA bootstrap", draft-richardson-anima-
              state-for-joinrouter-01 (work in progress), July 2016.

   [imprinting]
              Wikipedia, "Wikipedia article: Imprinting", July 2015,
              <https://en.wikipedia.org/wiki/Imprinting_(psychology)>.

   [RFC2473]  Conta, A. and S. Deering, "Generic Packet Tunneling in
              IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473,
              December 1998, <https://www.rfc-editor.org/info/rfc2473>.

   [RFC7217]  Gont, F., "A Method for Generating Semantically Opaque
              Interface Identifiers with IPv6 Stateless Address
              Autoconfiguration (SLAAC)", RFC 7217,
              DOI 10.17487/RFC7217, April 2014,
              <https://www.rfc-editor.org/info/rfc7217>.

   [RFC7435]  Dukhovni, V., "Opportunistic Security: Some Protection
              Most of the
   vendor to definitively know that the device is owned by the
   Registrar.

   The Registrar obtains the MASA URI via static configuration or by
   extracting it from the X.509 IDevID credential.  See Section 2.2.

   During initial bootstrapping the Pledge provides a nonce specific to
   the particular bootstrapping attempt.  [[RESOLVED: to resolve this I
   updated many points where vouchers are referenced]]The Registrar
   SHOULD include this nonce when claiming the Pledge from the MASA
   service.  Claims from Time", RFC 7435, DOI 10.17487/RFC7435,
              December 2014, <https://www.rfc-editor.org/info/rfc7435>.

   [RFC7575]  Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,
              Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
              Networking: Definitions and Design Goals", RFC 7575,
              DOI 10.17487/RFC7575, June 2015,
              <https://www.rfc-editor.org/info/rfc7575>.

   [Stajano99theresurrecting]
              Stajano, F. and R. Anderson, "The resurrecting duckling:
              security issues for ad-hoc wireless networks", 1999,
              <https://www.cl.cam.ac.uk/~fms27/
              papers/1999-StajanoAnd-duckling.pdf>.

Appendix A.  IPv4 operations

A.1.  IPv4 Link Local addresses

   Instead of an unauthenticated Registrar are only serviced
   by IPv6 link-local address, an IPv4 address may be
   generated using [RFC3927]  Dynamic Configuration of IPv4 Link-Local
   Addresses.

   In the MASA resource if a nonce is provided.

   The Registrar can claim a Pledge case that an IPv4 Local-Local address is offline by forming the
   request using formed, then the entities unique identifier and not including a
   nonce
   bootstrap process would continue as in the claim request.  Vouchers obtained in this way do not
   have a lifetime and they provide a permanent method IPv6 case by looking for the domain to
   claim the device.  Evidence of such a claim is
   (circuit) proxy.

A.2.  Use of DHCPv4

   The Plege MAY obtain an IP address via DHCP [RFC2131].  The DHCP
   provided in the audit
   log entries available to any future Registrar.  Such claims reduce
   the ability parameters for future domains to secure bootstrapping and therefore the Registrar MUST Domain Name System can be authenticated by used to perform
   DNS operations if all local discovery attempts fail.

Appendix B.  mDNS / DNSSD proxy discovery options

   The Pledge MAY perform DNS-based Service Discovery [RFC6763] over
   Multicast DNS [RFC6762] searching for the MASA service although no
   requirement is implied that the MASA associates this authentication
   with ownership.

   An Ownership Voucher requires the vendor to definitively know that a
   device is owned by a specific domain.
   "_bootstrapks._tcp.local.".

   To prevent unaccceptable levels of network traffic the congestion
   avoidance mechanisms specified in [RFC6762] section 7 MUST be
   followed.  The method used to "claim"
   this are out-of-scope.  A MASA ignores or reports failures when Pledge SHOULD listen for an
   attempt is made unsolicited broadcast
   response as described in [RFC6762].  This allows devices to claim a device that has avoid
   announcing their presence via mDNS broadcasts and instead silently
   join a an Ownership Voucher.

D.1.3.4.  Log Verification

   A Registrar requests the log information network by watching for the Pledge from the MASA
   service. periodic unsolicited broadcast
   responses.

   Performs DNS-based Service Discovery [RFC6763] over normal DNS
   operations.  The log service searched for is verified to confirm that
   "_bootstrapks._tcp.example.com".  In this case the following domain
   "example.com" is true
   to discovered as described in [RFC6763] section 11.
   This method is only available if the satisfaction of host has received a Registrar's configured policy:

   o  Any nonceless entries useable IPv4
   address via DHCPv4 as suggested in the log are associated with domainIDs
      recognized by the registrar.

   o  Any nonce'd entries are older than when the domain Appendix A.

   If no local bootstrapks service is known to
      have physical possession of located using the Pledge GRASP
   mechanisms, or that the domainIDs are
      recognized by the registrar.

   If any of these criteria are unacceptable to a Registrar above mentioned DNS-based Service Discovery
   methods the entity
   is rejected.  [[RESOLVED: moved to main body]] A Registrar Pledge MAY be
   configured to ignore the history of the device but it is RECOMMENDED
   that this only be configured if hardware assisted NEA [RFC5209] is
   supported.

   [[RESOLVED: added to main text]]This document specifies contact a simple log
   format as provided by the MASA service to the registar.  This format
   could be improved by distributed consensus technologies that
   integrate vouchers with well known vendor provided
   bootstrapping server by performing a technologies DNS lookup using a well known
   URI such as block-chain or hash
   trees or the like.  Doing so is out "bootstrapks.vendor-example.com".  The details of the scope of URI
   are vendor specific.  Vendors that leverage this document but method on the Pledge
   are anticipated improvements responsible for future work.

D.1.4.  Behavior of providing the MASA Service

   [[UNRESOLVED: primary value of keeping this discussion bootstrapks service.

   The current DNS services returned during each query is maintained
   until bootstrapping is completed.  If bootstrapping fails and the
   Pledge returns to
   distinguish between registrar the Discovery state it picks up where it left off
   and continues attempting bootstrapping.  For example if the first
   Multicast DNS _bootstrapks._tcp.local response doesn't work then the
   second and masa particularly wrt third responses are tried.  If these fail the Pledge moves
   on to normal DNS-based Service Discovery.

Appendix C.  IPIP Join Proxy mechanism

   The Circuit Proxy mechanism suffers from requiring a state on the
   protocol functions provided. perhaps add statements in
   Join Proxy for each protocol
   entry "provided by masa" etc?]]

   The Manufacturer Authorized Signing Authority service connection that is directly
   provided by the manufacturer, or relayed.  The Circuit Proxy
   can be provided by considered a third party kind of Algorithm Gateway [FIND-good-REF].

   An alternative to proxying at the
   manufacturer authorizes.  It TCP layer is a cloud resource.  The MASA service
   provides the following functionalities to Registrars:

   Issue Vouchers:  In response to Registrar requests the MASA service
      issues vouchers.  Depending on the MASA policy selectively forward
   at the Registrar claim
      of device ownership is either accepted or verified using out-of-
      scope methods (that are expected IP layer.  This moves all per-connection to improve over time).

   Log Vouchers Issued:  When a voucher is issued the act Join
   Registrar.  The IPIP tunnel statelessly forwards packets.  This
   section provides some explanation of some of the details of issuing it
      includes updating the certifiable logs.  Future work
   Registrar discovery procotol which are not important to enhance Circuit
   Proxy, and distribute these logs some implementation advice.

   The IPIP tunnel is out-of-scope described in [RFC2473].  Each such tunnel is
   considered a unidirectional construct, but expected over time.

   Provide Logs:  As two tunnels may be
   associated to form a baseline implementation of the certified logging
      mechanism the MASA bidirectional mechanism.  An IPIP tunnel is repsonsible for reporting logged
      information.
   setup as follows.  The current method involves trusting the MASA.
      Other logging methods where the MASA is less trusted outer addresses are expected
      to be developed over time.

D.1.5.  Leveraging an ACP address of the new key infrastructure / next steps

   As Join
   Proxy, and the devices have a common trust anchor, device identity can be
   securely established, making it possible to automatically deploy
   services across ACP address of the domain Join Registrar.  The inner
   addresses seen in a secure manner.

   Examples of services:

   o  Device management.

   o  Routing authentication.

   o  Service discovery.

D.1.5.1.  Network boundaries

   When a device has joined the domain, it can validate tunnel are the domain
   membership link-local addresses of other devices.  This makes it possible the
   network on which the join activity is occuring.

   One way to create trust
   boundaries where domain members have higher level of trusted than
   external devices.  Using look at this construct is to consider that the autonomic User Interface, specific
   devices can be grouped into Registrar
   is extending attaching an interface to sub domains and specific trust levels
   can be implemented between those.

D.1.6.  Interactions with Network Access Control

   [[RESOLVED: via paragraph in 'scope of solution' discussion.]] the network on which the Join
   Proxy is physically present.  The Registrar then interacts as if it
   were present on that network using link-local (fe80::) addresses.
   The assumption Join node is unaware that Network Access Control (NAC) completes using
   the Pledge 's X.509 IDevID credentials and results in the device
   having sufficient connectivity to discovery traffic is being proxied through a
   tunnel, and communicate does not need any special routing.

   There are a number of considerations with this mechanism which
   require cause some minor amounts of complexity.  Note that due to the
   proxy.  Any additional connectivity or quarantine behavior by
   tunnels, the NAC
   infrastructure is out-of-scope.  After Registrar sees multiple connections to a fe80::/10
   network on not just physical interfaces, but on each of the devices has completed
   bootstrapping virtual
   interfaces represending the mechanism to trigger NAC to re-authenticate tunnels.

C.1.  Multiple Join networks on the Join Proxy side

   The Join Proxy will in the general case be a routing device with
   multiple interfaces.  Even a device as simple as a wifi access point
   may have wired, and provide updated network privileges is also out-of-scope.

   This achieves the goal multiple frequencies of a bootstrap architecture that can integrate wireless interfaces,
   potentially with NAC but does not require NAC within multiple ESSIDs.

   Each of these interfaces on the network where it wasn't
   previously required.  Future optimizations can Join Proxy may be achieved seperate L3 routing
   domains, and therefore will have a unique set of link-local
   addresses.  An IPIP packet being returned by
   integrating the bootstrapping protocol directly into an initial EAP
   exchange.

D.2.  Domain Operator Activities

   This section describes how an operator interacts with a domain that
   supports Registrar needs to
   be forwarded to the bootstrapping as described in this document.

D.2.1.  Instantiating correct interface, so the Domain Certification Authority

   This is a one time step by Join Proxy needs an
   additional key to distinguish which network the domain administrator.  This packet should be
   returned to.

   The simplest way to get this additional key is to allocate an "off
   the shelf" CA with the exception that it
   additional ACP address; one address for each network on which join
   traffic is designed occuring.  The Join Proxy SHOULD do a GRASP M_NEG_SYN for
   each interface which they wish to work relay traffic, as an
   integrated part of the security solution.  This precludes this allows the use of
   3rd party certification authority services that
   Registrar to do not provide
   support for delegation any static tunnel configuration that may be required.

C.2.  Automatic configuration of certificate issuance decisions tunnels on Registrar

   The Join Proxy is expected to do a domain
   managed Registration Authority.

D.2.2.  Instantiating GRASP negotiation with the Registrar proxy
   for each Join Interface that it needs to relay traffic from.  This is a one time step by the domain administrator.  One or more
   devices in
   to permit Registrars to configure the domain are configured take on a Registrar function. appropriate virtual interfaces
   before join traffic arrives.

   A device can be configured to act as a Registrar or serving a device can
   auto-select itself large number of interfaces may not wish to take on this function, using a detection
   mechanism
   allocate resources to resolve potential conflicts every interface at all times, but can instead
   dynamically allocate interfaces.  It can do this by monitoring IPIP
   traffic that arrives on it's ACP interface, and setup communication with
   the Domain Certification Authority.  Automated when packets arrive
   from new Join Proxys, it can dynamically configure virtual
   interfaces.

   A more sophisticated Registrar selection is
   outside scope for this document.

D.2.3.  Accepting New Entities

   For each Pledge willing to modify the Registrar is informed behaviour of
   it's TCP and UDP stack could note the unique identifier
   (e.g. serial number) along with the manufacturer's identifying
   information (e.g. manufacturer root certificate).  This can happen in
   different ways:

   1.  Default acceptance: In IPIP traffic origination in the simplest case,
   socket control block and make information available to the new device asserts
       its unique identity TCP layer
   (for HTTPS connections), or to the application (for CoAP connections)
   via a Registrar.  The registrar accepts all
       devices without authorization checks.  This mode does not provide
       security against intruders and is not recommended.

   2.  Per device acceptance: The new device asserts its unique identity proprietary extension to a Registrar.  A non-technical human validates the identity,
       for example socket API.

C.3.  Proxy Neighbor Discovery by comparing Join Proxy

   The Join Proxy MUST answer neighbor discovery messages for the identity displayed
   address given by the registrar
       (for example using a smartphone app) with Registrar as being it's link-local address.  The
   Join Proxy must also advertise this address as the identity shown on address to which
   to connect to when advertising it's existence.

   This proxy neighbor discovery means that the packaging of pledge will create TCP
   and UDP connections to the device.  Acceptance may be triggered by a
       click on a smartphone app "accept this device", or by other forms
       of pairing.  See also [I-D.behringer-homenet-trust-bootstrap] for
       how correct Registrar address.  This matters
   as the approach could work in a homenet.

   3.  Whitelist acceptance: In larger networks, neither of TCP and UDP pseudo-header checksum includes the previous
       approaches is acceptable.  Default acceptance is not secure, destination
   address, and
       a manual per device methods do for the proxy to remain completely stateless, it must
   not scale.  Here, be necessary for the registrar is
       provided a priori with a list checksum to be updated.

C.4.  Use of identifiers connected sockets; or IP_PKTINFO for CoAP on Registrar

   TCP connections on the registrar SHOULD properly capture the ifindex
   of devices that
       belong to the network. incoming connection into the socket structure.  This list can be extracted from an
       inventory database, or sales records.  If a device is detected
       that is not normal
   IPv6 socket API processing.  The outgoing responses will go out on
   the list of known devices, it can still be
       manually accepted same (virtual) interface by ifindex.

   When using UDP sockets with CoAP, the per device acceptance methods.

   4.  Automated Whitelist: an automated process that builds application will have to pay
   attention to the
       necessary whitelists and inserts them into incoming ifindex on the larger network
       domain infrastructure is plausible.  Once set up, no human
       intervention is required in socket.  Access to this process.  Defining
   information is available using the exact
       mechanisms for this IP_PKTINFO auxiliary extension
   which is out a standard part of scope although the IPv6 sockets API.

   A registrar
       authorization checks is identified as the logical integration
       point of any future work in this area.

   None application could, after receipt of these approaches require the network to have permanent
   Internet connectivity.  Even when the Internet based MASA service is
   used, it is possible to pre-fetch the required information an initial CoAP
   message from the
   MASA Pledge, create a priori, for example at time connected UDP socket (including the
   ifindex information).  The kernel would then take care of purchase such that devices can
   enroll later.  This supports use cases where accurate
   demultiplexing upon receive, and subsequent transmission to the domain network
   correct interface.

C.5.  Use of socket extension rather than virtual interface

   Some operating systems on which a Registrar need be implemented may
   find need for a virtual interface per Join Proxy to be entirely isolated during device deployment.

   Additional policy problematic.
   There are other mechanism which can make be stored for future authorization decisions.
   For example done.

   If the IPIP decapsulator can mark the (SYN) packet inside the kernel
   with the address of the Join Proxy sending the traffic, then an expected deployment time window or that a certain
   interface per Join Proxy must may not be used.

D.2.4.  Automatic Enrollment of Devices needed.  The approach outlined in outgoing path need
   just pay attention to this document provides a secure zero-touch
   method extra information and add an appropriate
   IPIP header on outgoing.  A CoAP over UDP mechanism may need to
   expose this extra information to enroll new devices without any pre-staged configuration.
   New devices communicate with already enrolled devices of the domain,
   which proxy between application as the new device UDP sockets
   are often not connected, and a Registrar.  As a result of
   this completely automatic operation, all devices obtain a domain
   based certificate.

D.2.5.  Secure Network Operations

   The certificate installed in the previous step can be used for all
   subsequent operations.  For example, application will need to determine the boundaries of specify the domain: If a neighbor
   outgoing path on each packet send.

   Such an additional socket mechanism has a certificate not been standardized.
   Terminating L2TP connections over IPsec transport mode suffers from
   the same trust
   anchor it can be assumed "inside" the same organization; if not, as
   outside.  See also challenges.

Appendix D.1.5.1. D.  MUD Extension

   The certificate can also be
   used following extension augments the MUD model to securely establish include a connection between devices single
   node, as described in [I-D.ietf-opsawg-mud] section 3.6, using the
   following sample module that has the following tree structure:

   module: ietf-mud-brski-masa
   augment /ietf-mud:mud:
   +--rw masa-server?   inet:uri

   The model is defined as follows:

   <CODE BEGINS>
   module ietf-mud-brski-masa {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-mud-brski-masa";
     prefix ietf-mud-brski-masa;
     import ietf-mud {
       prefix ietf-mud;
     }
     import ietf-inet-types {
       prefix inet;
     }

     organization
       "IETF ANIMA (Autonomic Networking Integrated Model and central
   control functions.  Also autonomic transactions can use
       Approach) Working Group";
       contact
       "WG Web: http://tools.ietf.org/wg/anima/
       WG List: anima@ietf.org
       ";
     description
       "BRSKI extension to a MUD file to indicate the domain
   certificates
       MASA URL.";

     revision 2017-10-09 {
       description
       "Initial revision.";
       reference
       "RFC XXXX: Manufacturer Usage Description
       Specification";
     }

     augment "/ietf-mud:mud" {
       description
       "BRSKI extension to authenticate and/or encrypt direct interactions
   between devices.  The usage of a MUD file to indicate the domain certificates
       MASA URL.";
       leaf masa-server {
         type inet:uri;
         description
         "This value is outside
   scope for this document. the URI of the MASA server";
       }
     }
   }
   <CODE ENDS>

Authors' Addresses

   Max Pritikin
   Cisco

   Email: pritikin@cisco.com

   Michael C. Richardson
   Sandelman Software Works

   Email: mcr+ietf@sandelman.ca
   URI:   http://www.sandelman.ca/

   Michael H. Behringer
   Cisco

   Email: mbehring@cisco.com

   Steinthor Bjarnason
   Cisco
   Arbor Networks

   Email: sbjarnas@cisco.com sbjarnason@arbor.net

   Kent Watsen
   Juniper Networks

   Email: kwatsen@juniper.net