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Versions: 00 01 02 03 04 draft-birkholz-i2nsf-tuda

Network Working Group                                           A. Fuchs
Internet-Draft                                               H. Birkholz
Intended status: Informational                            Fraunhofer SIT
Expires: September 22, 2016                                  I. McDonald
                                                          High North Inc
                                                              C. Bormann
                                                 Universitaet Bremen TZI
                                                          March 21, 2016


                 Time-Based Uni-Directional Attestation
                         draft-birkholz-tuda-01

Abstract

   This memo documents the method and bindings used to conduct time-
   based uni-directional attestation between distinguishable endpoints
   over the network.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 22, 2016.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Concept . . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Time-Based Uni-Directional Attestation  . . . . . . . . . . .   5
     2.1.  TUDA Information Elements Update Cycles . . . . . . . . .   7
   3.  REST Realization  . . . . . . . . . . . . . . . . . . . . . .   9
   4.  SNMP Realization  . . . . . . . . . . . . . . . . . . . . . .   9
     4.1.  Structure of TUDA MIB . . . . . . . . . . . . . . . . . .  10
       4.1.1.  Cycle Index . . . . . . . . . . . . . . . . . . . . .  10
       4.1.2.  Instance Index  . . . . . . . . . . . . . . . . . . .  11
       4.1.3.  Fragment Index  . . . . . . . . . . . . . . . . . . .  11
     4.2.  Relationship to Host Resources MIB  . . . . . . . . . . .  11
     4.3.  Relationship to Entity MIB  . . . . . . . . . . . . . . .  12
     4.4.  Relationship to Other MIBs  . . . . . . . . . . . . . . .  12
     4.5.  Definition of TUDA MIB  . . . . . . . . . . . . . . . . .  12
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  27
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  27
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  27
   8.  Change Log  . . . . . . . . . . . . . . . . . . . . . . . . .  27
   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  27
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  27
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  28
     10.2.  Informative References . . . . . . . . . . . . . . . . .  28
   Appendix A.  Realization with TPM 1.2 functions . . . . . . . . .  30
     A.1.  TPM Functions . . . . . . . . . . . . . . . . . . . . . .  30
       A.1.1.  Tick-Session and Tick-Stamp . . . . . . . . . . . . .  30
       A.1.2.  Platform Configuration Registers (PCRs) . . . . . . .  31
       A.1.3.  PCR restricted Keys . . . . . . . . . . . . . . . . .  32
       A.1.4.  CertifyInfo . . . . . . . . . . . . . . . . . . . . .  32
     A.2.  Protocol and Procedure  . . . . . . . . . . . . . . . . .  32
       A.2.1.  AIK and AIK Certificate . . . . . . . . . . . . . . .  32
       A.2.2.  Synchronization Token . . . . . . . . . . . . . . . .  33
       A.2.3.  RestrictionInfo . . . . . . . . . . . . . . . . . . .  35
       A.2.4.  Measurement Log . . . . . . . . . . . . . . . . . . .  37
       A.2.5.  Implicit Attestation  . . . . . . . . . . . . . . . .  38
       A.2.6.  Attestation Verification Approach . . . . . . . . . .  39
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  41

1.  Introduction

   Remote attestation describes the attempt to determine the integrity
   and trustworthiness of a computing platform or device without direct
   access.  One way to do so is based on measurements of software



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   components, where the hash values of all started software components
   are stored (extended into) a Trust Anchor implemented as Hardware
   Security Module (such as TPM and similar) and reported via a
   signature over these measurements.  Protocols that facilitate these
   Trust Anchor based signatures in order to provide remote attestations
   are usually bi-directional protocols, where one entity sends a
   challenge that is included inside the response to ensure the
   recentness of the attestation information.

   In many contexts and scenarios it is not feasible to deploy bi-
   directional protocols, due to constraints in the underlying
   communication schemes.  Furthermore, many communication schemes do
   not have a notion of connection, which disallows the usage of
   connection context related state information.  These constraints may
   make it impossible to deploy challenge-response based schemes to
   achieve freshness of messages in security protocols.  Examples of
   these constrained environments include broadcast and multicast
   schemes such as automotive IEEE802.1p as well as communication models
   that do not maintain connection state over time, such as REST [REST]
   and SNMP [RFC3411].

   This document describes the protocol TUDA for remote attestation that
   works over uni-directional communication channels whilst still
   providing up-to-date information about the integrity and thereby
   trustworthiness of the attested device.  The information elements
   that are transported by TUDA are encoded in the Concise Binary Object
   Representation, CBOR [RFC7049].  In this specification, the
   composition of the CBOR data items that represent the information
   elements is described using the CBOR Data Definition Language, CDDL
   [I-D.greevenbosch-appsawg-cbor-cddl].

1.1.  Concept

   The protocols usually employed for Remote Attestations using the
   Trusted Platform Module (TPM) - such as the Platform Trust Service
   (PTS) Protocol [PTS] - as specified by the Trusted Computing Group
   (TCG) are based upon the TPM_Quote() function.  It consists of the
   sending of a nonce-challenge that is then used within TPM_Quote()'s
   signature to prove the freshness of the Attestation response.  This
   scheme requires bi-directional communication.

   The TUDA protocol specification describes a new scheme for remote
   attestations based upon a combination of TPM_CertifyInfo() and
   TPM_TickStampBlob() to implement a time-based attestation scheme.The
   approach is based upon the work described in [MTAF] and [SFKE2008].

   The freshness properties of a challenge-response based protocol
   define the time-frame between the transmission of the nonce and the



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   reception of the response as the point in time of attestation.  Given
   the time-based attestation scheme, the point in time of attestation
   lies within the time-frame given by the accuracy of the time-
   synchronization and the drift of clocks.  If the point in time is
   within the range of the typical round-trip of a challenge response
   attestation, the freshness property of TUDA is equivalent to that of
   classic challenge response attestation.  Even if the typical round-
   trip time is exceeded slightly, the TUDA attestation statements
   provide sufficiently fresh proofs for most scenarios.

   In contrast to classical attestations, TUDA attestations can serve as
   proof of integrity in audit logs with point in time guarantees.
   Also, it can be used via uni-directional and connection-less
   communication channels.

   Appendix A contains a realization of TUDA using TPM 1.2 primitives.
   A realization of TUDA using TPM 2.0 primitives will be added with the
   next iteration of this document.

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 RFC
   2119, BCP 14 [RFC2119].

   This specification makes use of the terminology defined in [RFC4949]
   and uses CDDL as defined in [I-D.greevenbosch-appsawg-cbor-cddl] to
   define the composition of the TUDA information elements.

   The data structures defined by this protocol specification (for use
   by other specifications) introduce TUDA-specific terminology:

   tuda = [TUDA-Synctoken, TUDA-Verifytoken, TUDA-RestrictionInfo,
           TUDA-Cert, TUDA-Measurement-Log]

   Common types used in these are:

   Cert = bytes ; an X.509 certificate

   PCR-Hash = Hash
   Hash = bytes

   The roles used in the TUDA protocol are:

   Attestee:  the endpoint that is the subject of the attestation to
      another endpoint.




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   Verifier:  the endpoint that consumes the attestation of another
      endpoint.

   TSA:  Time Stamp Authority [RFC3161].

   Types of certificates that are essential to the TUDA protocol:

   TSA-CA:  a Certificate Authority, that provides the certificate for
      the TSA.

   AIK-CA:  The Attestation Identity Key (AIK) is a special key type
      used within TPMs for identity-related operations (such as
      TPM_Certify or TPM_Quote).  Such an AIK can be established in many
      ways, using either a combination of TPM_MakeIdentity and
      TPM_ActivateIdentity with a so-called PrivacyCA [AIK-Enrollment]
      or by means of TPM_CreateWrapKey, readout in a secure environment
      and regular certification by a custom CA similar to IDevIDs or
      LDevIDs in [IEEE802.1AR].  AIK-CA is a placeholder for any CA and
      AIK-Cert is a placeholder for the corresponding Certificate,
      depending on what protocol was used.  The specific protocols are
      out of scope for this document.

   Terms that are commonly used in this document and not necessarily
   self-explaining:

   PCR:  a Platform Configuration Register that is part of a Trusted
      Platform Module and is used to securely store and report
      measurements about security posture.

   In this specification, the term "byte" is used in its now customary
   sense as a synonym for "octet".

2.  Time-Based Uni-Directional Attestation

   A Time-Based Uni-Directional Attestation (TUDA) consists of the
   following seven information elements.  They are used to gain
   assurance of the Attestee's platform configuration at a certain point
   in time:

   o  TSA Certificate

      The certificate of the Time Stamp Authority that is used in a
      subsequent synchronization protocol token.  This certificate is
      signed by the TSA-CA.

   o  AIK Certificate ([AIK-Credential], [AIK-Enrollment]; see
      Appendix A.2.1).




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      A certificate about the Attestation Identity Key (AIK) used.  This
      may or may not also be an [IEEE802.1AR] IDevID or LDevID,
      depending on their setting of the corresponding identity property.

   o  Synchronization Token

      The reference for Attestations are the Tick-Sessions of the TPM.
      In order to put Attestations into relation with a Real Time Clock
      (RTC), it is necessary to provide a cryptographic synchronization
      between the tick session and the RTC.  To do so, a synchronization
      protocol is run with a Time Stamp Authority (TSA).

   o  Restriction Info

      The attestation relies on the capability of the TPM to operate on
      restricted keys.  Whenever the PCR values for the machine to be
      attested change, a new restricted key is created that can only be
      operated as long as the PCRs remain in their current state.

      In order to prove to the Verifier that this restricted temporary
      key actually has these properties and also to provide the PCR
      value that it is restricted, the TPM command TPM_CertifyInfo is
      used.  It creates a signed certificate using the AIK about the
      newly created restricted key.

   o  Measurement Log

      Similarly to regular attestations, the Verifier needs a way to
      reconstruct the PCRs' values in order to estimate the
      trustworthiness of the device.  As such, a list of those elements
      that were extended into the PCRs is reported.  Note though that
      for certain environments, this step may be optional if a list of
      valid PCR configurations exists and no measurement log is
      required.

   o  Implicit Attestation

      The actual attestation is then based upon a TPM_TickStampBlob
      operation using the restricted temporary key that was certified in
      the steps above.  The TPM_TickStampBlob is executed and thereby
      provides evidence that at this point in time (with respect to the
      TPM internal tick-session) a certain configuration existed (namely
      the PCR values associated with the restricted key).  Together with
      the synchronization token this tick-related timing can then be
      related to the real-time clock.

   o  Concise SWID tags




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      As an option to better assess the trustworthiness of an Attestee,
      a Verifier can request the reference hashes (often referred to as
      golden measurements) of all started software components to compare
      them with the entries in the measurement log.  References hashes
      regarding installed (and therefore running) software can be
      provided by the manufacturer via SWID tags.  SWID tags are
      provided by the Attestee using the Concise SWID representation
      [I-D-birkholz-sacm-coswid] and bundled into a CBOR array.
      Ideally, the reference hashes include a signature created by the
      manufacturer of the software.

   These information elements could be sent en bloc, but it is
   recommended to retrieve them separately to save bandwidth, since
   these elements have different update cycles.  In most cases,
   retransmitting all seven information elements would result in
   unnecessary redundancy.

   Furthermore, in some scenarios it might be feasible not to store all
   elements on the Attestee endpoint, but instead they could be
   retrieved from another location or pre-deployed to the Verifier.  It
   is also feasible to only store public keys at the Verifier and skip
   the whole certificate provisioning completely in order to save
   bandwidth and computation time for certificate verification.

2.1.  TUDA Information Elements Update Cycles

   An endpoint can be in various states and have various information
   associated with it during its life cycle.  For TUDA, a subset of the
   states (which can include associated information) that an endpoint
   and its TPM can be in, is important to the attestation process.

   o  Some states are persistent, even after reboot.  This includes
      certificates that are associated with the endpoint itself or with
      services it relies on.

   o  Some states are more volatile and change at the beginning of each
      boot cycle.  This includes the TPM-internal Tick-Session which
      provides the basis for the synchronization token and implicit
      attestation.

   o  Some states are even more volatile and change during an uptime
      cycle (the period of time an endpoint is powered on, starting with
      its boot).  This includes the content of PCRs of a TPM and thereby
      also the PCR-restricted keys used during attestation.

   Depending on this "lifetime of state", data has to be transported
   over the wire, or not.  E.g. information that does not change due to




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   a reboot typically has to be transported only once between the
   Attestee and the Verifier.

   There are three kinds of events that require a renewed attestation:

   o  The Attestee completes a boot-cycle

   o  A relevant PCR changes

   o  Too much time has passed since the last attestation statement

   The third event listed above is variable per application use case and
   can therefore be set appropriately.  For usage scenarios, in which
   the device would periodically push information to be used in an
   audit-log, a time-frame of approximately one update per minute should
   be sufficient in most cases.  For those usage scenarios, where
   verifiers request (pull) a fresh attestation statement, an
   implementation could use the TPM continuously to always present the
   most freshly created results.  To save some utilization of the TPM
   for other purposes, however, a time-frame of once per ten seconds is
   recommended, which would leave 80% of utilization for applications.

   Attestee                                                 Verifier
      |                                                         |
    Boot                                                        |
      |                                                         |
    Create Sync-Token                                           |
      |                                                         |
    Create Restricted Key                                       |
    Certify Restricted Key                                      |
      |                                                         |
      | AIK-Cert ---------------------------------------------> |
      | Sync-Token -------------------------------------------> |
      | Certify-Info -----------------------------------------> |
      | Measurement Log --------------------------------------> |
      | Attestation ------------------------------------------> |
      |                                           Verify Attestation
      |                                                         |
      |       <Time Passed>                                     |
      |                                                         |
      | Attestation ------------------------------------------> |
      |                                           Verify Attestation
      |                                                         |
      |       <Time Passed>                                     |
      |                                                         |
    PCR-Change                                                  |
      |                                                         |
    Create Restricted Key                                       |



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    Certify Restricted Key                                      |
      |                                                         |
      | Certify-Info -----------------------------------------> |
      | Measurement Log --------------------------------------> |
      | Attestation ------------------------------------------> |
      |                                           Verify Attestation
      |                                                         |
    Boot                                                        |
      |                                                         |
    Create Sync-Token                                           |
      |                                                         |
    Create Restricted Key                                       |
    Certify Restricted Key                                      |
      |                                                         |
      | Sync-Token -------------------------------------------> |
      | Certify-Info -----------------------------------------> |
      | Measurement Log --------------------------------------> |
      | Attestation ------------------------------------------> |
      |                                           Verify Attestation
      |                                                         |
      |       <Time Passed>                                     |
      |                                                         |
      | Attestation ------------------------------------------> |
      |                                           Verify Attestation
      |                                                         |

                   Figure 1: Example sequence of events

3.  REST Realization

   Each of the seven data items is defined as a media type (Section 5).
   Representations of resources for each of these media types can be
   retrieved from URIs that are defined by the respective servers
   [RFC7320].  As can be derived from the URI, the actual retrieval is
   via one of the HTTPs ([RFC7230], [RFC7540]) or CoAP [RFC7252].  How a
   client obtains these URIs is dependent on the application; e.g., CoRE
   Web links [RFC6690] can be used to obtain the relevant URIs from the
   self-description of a server, or they could be prescribed by a
   RESTCONF data model [I-D.ietf-netconf-restconf].

4.  SNMP Realization

   SNMPv3 [STD62] [RFC3411] is widely available on computers and also
   constrained devices.  To transport the TUDA information elements, an
   SNMP MIB is defined below which encodes each of the seven TUDA
   information elements into a table.  Each row in a table contains a
   single read-only columnar SNMP object of datatype OCTET-STRING.  The
   values of a set of rows in each table can be concatenated to



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   reconstitute a CBOR-encoded TUDA information element.  The Verifier
   can retrieve the values for each CBOR fragment by using SNMP GetNext
   requests to "walk" each table and can decode each of the CBOR-encoded
   data items based on the corresponding CDDL
   [I-D.greevenbosch-appsawg-cbor-cddl] definition.

   Design Principles:

   1.  Over time, TUDA attestation values age and should no longer be
       used.  Every table in the TUDA MIB has a primary index with the
       value of a separate scalar cycle counter object that
       disambiguates the transition from one attestation cycle to the
       next.

   2.  Over time, the measurement log information (for example) may grow
       large.  Therefore, read-only cycle counter scalar objects in all
       TUDA MIB object groups facilitate more efficient access with SNMP
       GetNext requests.

   3.  Notifications are supported by an SNMP trap definition with all
       of the cycle counters as bindings, to alert a Verifier that a new
       attestation cycle has occurred (e.g., synchronization data,
       measurement log, etc. have been updated by adding new rows and
       possibly deleting old rows).

4.1.  Structure of TUDA MIB

   The following table summarizes the object groups, tables and their
   indexes, and conformance requirements for the TUDA MIB:

   |-------------|-------|----------|----------|----------|
   | Group/Table | Cycle | Instance | Fragment | Required |
   |-------------|-------|----------|----------|----------|
   | General     |       |          |          | x        |
   | AIKCert     | x     | x        | x        |          |
   | TSACert     | x     | x        | x        |          |
   | SyncToken   | x     |          | x        | x        |
   | Restrict    | x     |          |          | x        |
   | Measure     | x     | x        |          |          |
   | VerifyToken | x     |          |          | x        |
   | SWIDTag     | x     | x        | x        |          |
   |-------------|-------|----------|----------|----------|

4.1.1.  Cycle Index

   A tudaV1<Group>CycleIndex is the:





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   1.  first index of a row (element instance or element fragment) in
       the tudaV1<Group>Table;

   2.  identifier of an update cycle on the table, when rows were added
       and/or deleted from the table (bounded by tudaV1<Group>Cycles);
       and

   3.  binding in the tudaV1TrapV2Cycles notification for directed
       polling.

4.1.2.  Instance Index

   A tudaV1<Group>InstanceIndex is the:

   1.  second index of a row (element instance or element fragment) in
       the tudaV1<Group>Table; except for

   2.  a row in the tudaV1SyncTokenTable (that has only one instance per
       cycle).

4.1.3.  Fragment Index

   A tudaV1<Group>FragmentIndex is the:

   1.  last index of a row (always an element fragment) in the
       tudaV1<Group>Table; and

   2.  accomodation for SNMP transport mapping restrictions for large
       string elements that require fragmentation.

4.2.  Relationship to Host Resources MIB

   The General group in the TUDA MIB is analogous to the System group in
   the Host Resources MIB [RFC2790] and provides context information for
   the TUDA attestation process.

   The Verify Token group in the TUDA MIB is analogous to the Device
   group in the Host MIB and represents the verifiable state of a TPM
   device and its associated system.

   The SWID Tag group (containing a Concise SWID reference hash profile
   [I-D-birkholz-sacm-coswid]) in the TUDA MIB is analogous to the
   Software Installed and Software Running groups in the Host Resources
   MIB [RFC2790].







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4.3.  Relationship to Entity MIB

   The General group in the TUDA MIB is analogous to the Entity General
   group in the Entity MIB v4 [RFC6933] and provides context information
   for the TUDA attestation process.

   The SWID Tag group in the TUDA MIB is analogous to the Entity Logical
   group in the Entity MIB v4 [RFC6933].

4.4.  Relationship to Other MIBs

   The General group in the TUDA MIB is analogous to the System group in
   MIB-II [RFC1213] and the System group in the SNMPv2 MIB [RFC3418] and
   provides context information for the TUDA attestation process.

4.5.  Definition of TUDA MIB

   <CODE BEGINS>
   TUDA-V1-ATTESTATION-MIB DEFINITIONS ::= BEGIN

   IMPORTS
       MODULE-IDENTITY, OBJECT-TYPE, Integer32, Counter32,
       enterprises, NOTIFICATION-TYPE
           FROM SNMPv2-SMI                 -- RFC 2578
       MODULE-COMPLIANCE, OBJECT-GROUP, NOTIFICATION-GROUP
           FROM SNMPv2-CONF                -- RFC 2580
       SnmpAdminString
           FROM SNMP-FRAMEWORK-MIB;        -- RFC 3411

   tudaV1MIB MODULE-IDENTITY
       LAST-UPDATED    "201603210000Z"  -- 21 March 2016
       ORGANIZATION
           "Fraunhofer SIT"
       CONTACT-INFO
           "Andreas Fuchs
           Fraunhofer Institute for Secure Information Technology
           Email: andreas.fuchs@sit.fraunhofer.de

           Henk Birkholz
           Fraunhofer Institute for Secure Information Technology
           Email: henk.birkholz@sit.fraunhofer.de

           Ira E McDonald
           High North Inc
           Email: blueroofmusic@gmail.com

           Carsten Bormann
           Universitaet Bremen TZI



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           Email: cabo@tzi.org"

       DESCRIPTION
           "The MIB module for monitoring of time-based unidirectional
           attestation information from a network endpoint system,
           based on the Trusted Computing Group TPM 1.2 definition.

           Copyright (C) High North Inc (2016)."

       REVISION "201603210000Z" -- 21 March 2016
       DESCRIPTION
           "Second version, published as draft-birkholz-tuda-01."

       REVISION "201510180000Z" -- 18 October 2015
       DESCRIPTION
           "Initial version, published as draft-birkholz-tuda-00."

           ::= { enterprises fraunhofersit(21616) mibs(1) tudaV1MIB(1) }

   tudaV1MIBNotifications      OBJECT IDENTIFIER ::= { tudaV1MIB 0 }
   tudaV1MIBObjects            OBJECT IDENTIFIER ::= { tudaV1MIB 1 }
   tudaV1MIBConformance        OBJECT IDENTIFIER ::= { tudaV1MIB 2 }

   --
   --  General
   --
   tudaV1General           OBJECT IDENTIFIER ::= { tudaV1MIBObjects 1 }

   tudaV1GeneralCycles OBJECT-TYPE
       SYNTAX      Counter32
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "Count of TUDA update cycles that have occurred, i.e.,
           sum of all the individual group cycle counters.

           DEFVAL intentionally omitted - counter object."
       ::= { tudaV1General 1 }

   tudaV1GeneralVersionInfo OBJECT-TYPE
       SYNTAX      SnmpAdminString (SIZE(0..255))
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "Version information for TUDA MIB, e.g., specific release
           version of TPM 1.2 base specification and release version
           of TPM 1.2 errata specification and manufacturer and model
           TPM module itself."



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       DEFVAL      { "" }
       ::= { tudaV1General 2 }

   --
   --  AIK Cert
   --
   tudaV1AIKCert           OBJECT IDENTIFIER ::= { tudaV1MIBObjects 2 }

   tudaV1AIKCertCycles OBJECT-TYPE
       SYNTAX      Counter32
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "Count of AIK Certificate chain update cycles that have
           occurred.

           DEFVAL intentionally omitted - counter object."
       ::= { tudaV1AIKCert 1 }

   tudaV1AIKCertTable OBJECT-TYPE
       SYNTAX      SEQUENCE OF TudaV1AIKCertEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "A table of fragments of AIK Certificate data."
       ::= { tudaV1AIKCert 2 }

   tudaV1AIKCertEntry OBJECT-TYPE
       SYNTAX      TudaV1AIKCertEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "An entry for one fragment of AIK Certificate data."
       INDEX       { tudaV1AIKCertCycleIndex,
                     tudaV1AIKCertInstanceIndex,
                     tudaV1AIKCertFragmentIndex }
       ::= { tudaV1AIKCertTable 1 }

   TudaV1AIKCertEntry ::=
       SEQUENCE {
           tudaV1AIKCertCycleIndex         Integer32,
           tudaV1AIKCertInstanceIndex      Integer32,
           tudaV1AIKCertFragmentIndex      Integer32,
           tudaV1AIKCertData               OCTET STRING
       }

   tudaV1AIKCertCycleIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)



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       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "High-order index of this AIK Certificate fragment.
           Index of an AIK Certificate chain update cycle that has
           occurred (bounded by the value of tudaV1AIKCertCycles).

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1AIKCertEntry 1 }

   tudaV1AIKCertInstanceIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "Middle index of this AIK Certificate fragment.
           Ordinal of this AIK Certificate in this chain, where the AIK
           Certificate itself has an ordinal of '1' and higher ordinals
           go *up* the certificate chain to the Root CA.

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1AIKCertEntry 2 }

   tudaV1AIKCertFragmentIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "Low-order index of this AIK Certificate fragment.

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1AIKCertEntry 3 }

   tudaV1AIKCertData OBJECT-TYPE
       SYNTAX      OCTET STRING (SIZE(0..1024))
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "A fragment of CBOR encoded AIK Certificate data."
       DEFVAL      { "" }
       ::= { tudaV1AIKCertEntry 4 }

   --
   --  TSA Cert
   --
   tudaV1TSACert           OBJECT IDENTIFIER ::= { tudaV1MIBObjects 3 }

   tudaV1TSACertCycles OBJECT-TYPE



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       SYNTAX      Counter32
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "Count of TSA Certificate chain update cycles that have
           occurred.

           DEFVAL intentionally omitted - counter object."
       ::= { tudaV1TSACert 1 }

   tudaV1TSACertTable OBJECT-TYPE
       SYNTAX      SEQUENCE OF TudaV1TSACertEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "A table of fragments of TSA Certificate data."
       ::= { tudaV1TSACert 2 }

   tudaV1TSACertEntry OBJECT-TYPE
       SYNTAX      TudaV1TSACertEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "An entry for one fragment of TSA Certificate data."
       INDEX       { tudaV1TSACertCycleIndex,
                     tudaV1TSACertInstanceIndex,
                     tudaV1TSACertFragmentIndex }
       ::= { tudaV1TSACertTable 1 }

   TudaV1TSACertEntry ::=
       SEQUENCE {
           tudaV1TSACertCycleIndex         Integer32,
           tudaV1TSACertInstanceIndex      Integer32,
           tudaV1TSACertFragmentIndex      Integer32,
           tudaV1TSACertData               OCTET STRING
       }

   tudaV1TSACertCycleIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "High-order index of this TSA Certificate fragment.
           Index of a TSA Certificate chain update cycle that has
           occurred (bounded by the value of tudaV1TSACertCycles).

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1TSACertEntry 1 }



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   tudaV1TSACertInstanceIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "Middle index of this TSA Certificate fragment.
           Ordinal of this TSA Certificate in this chain, where the TSA
           Certificate itself has an ordinal of '1' and higher ordinals
           go *up* the certificate chain to the Root CA.

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1TSACertEntry 2 }

   tudaV1TSACertFragmentIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "Low-order index of this TSA Certificate fragment.

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1TSACertEntry 3 }

   tudaV1TSACertData OBJECT-TYPE
       SYNTAX      OCTET STRING (SIZE(0..1024))
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "A fragment of CBOR encoded TSA Certificate data."
       DEFVAL      { "" }
       ::= { tudaV1TSACertEntry 4 }

   --
   --  Sync Token
   --
   tudaV1SyncToken         OBJECT IDENTIFIER ::= { tudaV1MIBObjects 4 }

   tudaV1SyncTokenCycles OBJECT-TYPE
       SYNTAX      Counter32
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "Count of Sync Token update cycles that have
           occurred.

           DEFVAL intentionally omitted - counter object."
       ::= { tudaV1SyncToken 1 }




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   tudaV1SyncTokenTable OBJECT-TYPE
       SYNTAX      SEQUENCE OF TudaV1SyncTokenEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "A table of fragments of Sync Token data."
       ::= { tudaV1SyncToken 2 }

   tudaV1SyncTokenEntry OBJECT-TYPE
       SYNTAX      TudaV1SyncTokenEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "An entry for one fragment of Sync Token data."
       INDEX       { tudaV1SyncTokenCycleIndex,
                     tudaV1SyncTokenFragmentIndex }
       ::= { tudaV1SyncTokenTable 1 }

   TudaV1SyncTokenEntry ::=
       SEQUENCE {
           tudaV1SyncTokenCycleIndex       Integer32,
           tudaV1SyncTokenFragmentIndex    Integer32,
           tudaV1SyncTokenData             OCTET STRING
       }

   tudaV1SyncTokenCycleIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "High-order index of this Sync Token fragment.
           Index of a Sync Token update cycle that has
           occurred (bounded by the value of tudaV1SyncTokenCycles).

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1SyncTokenEntry 1 }

   tudaV1SyncTokenFragmentIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "Low-order index of this Sync Token fragment.

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1SyncTokenEntry 2 }

   tudaV1SyncTokenData OBJECT-TYPE



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       SYNTAX      OCTET STRING (SIZE(0..1024))
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "A fragment of CBOR encoded Sync Token data."
       DEFVAL      { "" }
       ::= { tudaV1SyncTokenEntry 3 }

   --
   --  Restriction Info
   --
   tudaV1Restrict          OBJECT IDENTIFIER ::= { tudaV1MIBObjects 5 }

   tudaV1RestrictCycles OBJECT-TYPE
       SYNTAX      Counter32
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "Count of Restriction Info update cycles that have
           occurred.

           DEFVAL intentionally omitted - counter object."
       ::= { tudaV1Restrict 1 }

   tudaV1RestrictTable OBJECT-TYPE
       SYNTAX      SEQUENCE OF TudaV1RestrictEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "A table of instances of Restriction Info data."
       ::= { tudaV1Restrict 2 }

   tudaV1RestrictEntry OBJECT-TYPE
       SYNTAX      TudaV1RestrictEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "An entry for one instance of Restriction Info data."
       INDEX       { tudaV1RestrictCycleIndex }
       ::= { tudaV1RestrictTable 1 }

   TudaV1RestrictEntry ::=
       SEQUENCE {
           tudaV1RestrictCycleIndex        Integer32,
           tudaV1RestrictData              OCTET STRING
       }

   tudaV1RestrictCycleIndex OBJECT-TYPE



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       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "Index of this Restriction Info entry.
           Index of a Restriction Info update cycle that has
           occurred (bounded by the value of tudaV1RestrictCycles).

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1RestrictEntry 1 }


   tudaV1RestrictData OBJECT-TYPE
       SYNTAX      OCTET STRING (SIZE(0..1024))
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "An instance of CBOR encoded Restriction Info data."
       DEFVAL      { "" }
       ::= { tudaV1RestrictEntry 2 }

   --
   --  Measurement Log
   --
   tudaV1Measure           OBJECT IDENTIFIER ::= { tudaV1MIBObjects 6 }

   tudaV1MeasureCycles OBJECT-TYPE
       SYNTAX      Counter32
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "Count of Measurement Log update cycles that have
           occurred.

           DEFVAL intentionally omitted - counter object."
       ::= { tudaV1Measure 1 }

   tudaV1MeasureInstances OBJECT-TYPE
       SYNTAX      Counter32
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "Count of Measurement Log instance entries that have
           been recorded (some entries MAY have been pruned).

           DEFVAL intentionally omitted - counter object."
       ::= { tudaV1Measure 2 }




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   tudaV1MeasureTable OBJECT-TYPE
       SYNTAX      SEQUENCE OF TudaV1MeasureEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "A table of instances of Measurement Log data."
       ::= { tudaV1Measure 3 }

   tudaV1MeasureEntry OBJECT-TYPE
       SYNTAX      TudaV1MeasureEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "An entry for one instance of Measurement Log data."
       INDEX       { tudaV1MeasureCycleIndex,
                     tudaV1MeasureInstanceIndex }
       ::= { tudaV1MeasureTable 1 }

   TudaV1MeasureEntry ::=
       SEQUENCE {
           tudaV1MeasureCycleIndex         Integer32,
           tudaV1MeasureInstanceIndex      Integer32,
           tudaV1MeasureData               OCTET STRING
       }

   tudaV1MeasureCycleIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "High-order index of this Measurement Log entry.
           Index of a Measurement Log update cycle that has
           occurred (bounded by the value of tudaV1MeasureCycles).

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1MeasureEntry 1 }

   tudaV1MeasureInstanceIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "Low-order index of this Measurement Log entry.
           Ordinal of this instance of Measurement Log data
           (NOT bounded by the value of tudaV1MeasureInstances).

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1MeasureEntry 2 }



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   tudaV1MeasureData OBJECT-TYPE
       SYNTAX      OCTET STRING (SIZE(0..1024))
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "A instance of CBOR encoded Measurement Log data."
       DEFVAL      { "" }
       ::= { tudaV1MeasureEntry 3 }

   --
   --  Verify Token
   --
   tudaV1VerifyToken       OBJECT IDENTIFIER ::= { tudaV1MIBObjects 7 }

   tudaV1VerifyTokenCycles OBJECT-TYPE
       SYNTAX      Counter32
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "Count of Verify Token update cycles that have
           occurred.

           DEFVAL intentionally omitted - counter object."
       ::= { tudaV1VerifyToken 1 }

   tudaV1VerifyTokenTable OBJECT-TYPE
       SYNTAX      SEQUENCE OF TudaV1VerifyTokenEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "A table of instances of Verify Token data."
       ::= { tudaV1VerifyToken 2 }

   tudaV1VerifyTokenEntry OBJECT-TYPE
       SYNTAX      TudaV1VerifyTokenEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "An entry for one instance of Verify Token data."
       INDEX       { tudaV1VerifyTokenCycleIndex }
       ::= { tudaV1VerifyTokenTable 1 }

   TudaV1VerifyTokenEntry ::=
       SEQUENCE {
           tudaV1VerifyTokenCycleIndex     Integer32,
           tudaV1VerifyTokenData           OCTET STRING
       }




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   tudaV1VerifyTokenCycleIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "Index of this instance of Verify Token data.
           Index of a Verify Token update cycle that has
           occurred (bounded by the value of tudaV1VerifyTokenCycles).

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1VerifyTokenEntry 1 }

   tudaV1VerifyTokenData OBJECT-TYPE
       SYNTAX      OCTET STRING (SIZE(0..1024))
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "A instance of CBOR encoded Verify Token data."
       DEFVAL      { "" }
       ::= { tudaV1VerifyTokenEntry 2 }

   --
   --  SWID Tag
   --
   tudaV1SWIDTag           OBJECT IDENTIFIER ::= { tudaV1MIBObjects 8 }

   tudaV1SWIDTagCycles OBJECT-TYPE
       SYNTAX      Counter32
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "Count of SWID Tag update cycles that have occurred.

           DEFVAL intentionally omitted - counter object."
       ::= { tudaV1SWIDTag 1 }

   tudaV1SWIDTagTable OBJECT-TYPE
       SYNTAX      SEQUENCE OF TudaV1SWIDTagEntry
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "A table of fragments of SWID Tag data."
       ::= { tudaV1SWIDTag 2 }

   tudaV1SWIDTagEntry OBJECT-TYPE
       SYNTAX      TudaV1SWIDTagEntry
       MAX-ACCESS  not-accessible
       STATUS      current



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       DESCRIPTION
           "An entry for one fragment of SWID Tag data."
       INDEX       { tudaV1SWIDTagCycleIndex,
                     tudaV1SWIDTagInstanceIndex,
                     tudaV1SWIDTagFragmentIndex }
       ::= { tudaV1SWIDTagTable 1 }

   TudaV1SWIDTagEntry ::=
       SEQUENCE {
           tudaV1SWIDTagCycleIndex         Integer32,
           tudaV1SWIDTagInstanceIndex      Integer32,
           tudaV1SWIDTagFragmentIndex      Integer32,
           tudaV1SWIDTagData               OCTET STRING
       }

   tudaV1SWIDTagCycleIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "High-order index of this SWID Tag fragment.
           Index of an SWID Tag update cycle that has
           occurred (bounded by the value of tudaV1SWIDTagCycles).

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1SWIDTagEntry 1 }

   tudaV1SWIDTagInstanceIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "Middle index of this SWID Tag fragment.
           Ordinal of this SWID Tag instance in this update cycle.

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1SWIDTagEntry 2 }

   tudaV1SWIDTagFragmentIndex OBJECT-TYPE
       SYNTAX      Integer32 (1..2147483647)
       MAX-ACCESS  not-accessible
       STATUS      current
       DESCRIPTION
           "Low-order index of this SWID Tag fragment.

           DEFVAL intentionally omitted - index object."
       ::= { tudaV1SWIDTagEntry 3 }




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   tudaV1SWIDTagData OBJECT-TYPE
       SYNTAX      OCTET STRING (SIZE(0..1024))
       MAX-ACCESS  read-only
       STATUS      current
       DESCRIPTION
           "A fragment of CBOR encoded SWID Tag data."
       DEFVAL      { "" }
       ::= { tudaV1SWIDTagEntry 4 }

   --
   --  Trap Cycles
   --
   tudaV1TrapV2Cycles NOTIFICATION-TYPE
       OBJECTS {
           tudaV1GeneralCycles,
           tudaV1AIKCertCycles,
           tudaV1TSACertCycles,
           tudaV1SyncTokenCycles,
           tudaV1RestrictCycles,
           tudaV1MeasureCycles,
           tudaV1MeasureInstances,
           tudaV1VerifyTokenCycles,
           tudaV1SWIDTagCycles
       }
       STATUS  current
       DESCRIPTION
           "This trap is sent when the value of any cycle or instance
           counter changes (i.e., one or more tables are updated).

           Note:  The value of sysUpTime in IETF MIB-II (RFC 1213) is
           always included in SNMPv2 traps, per RFC 3416."
       ::= { tudaV1MIBNotifications 1 }

   --
   --  Conformance Information
   --
   tudaV1Compliances           OBJECT IDENTIFIER
       ::= { tudaV1MIBConformance 1 }

   tudaV1ObjectGroups          OBJECT IDENTIFIER
       ::= { tudaV1MIBConformance 2 }

   tudaV1NotificationGroups    OBJECT IDENTIFIER
       ::= { tudaV1MIBConformance 3 }

   --
   --  Compliance Statements
   --



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   tudaV1BasicCompliance MODULE-COMPLIANCE
       STATUS  current
       DESCRIPTION
           "An implementation that complies with this module MUST
           implement all of the objects defined in the mandatory
           group tudaV1BasicGroup."
       MODULE  -- this module
       MANDATORY-GROUPS { tudaV1BasicGroup }

       GROUP   tudaV1OptionalGroup
       DESCRIPTION
           "The optional TUDA MIB objects.
           An implementation MAY implement this group."

       GROUP   tudaV1TrapGroup
       DESCRIPTION
           "The TUDA MIB traps.
           An implementation SHOULD implement this group."
       ::= { tudaV1Compliances 1 }

   --
   --  Compliance Groups
   --
   tudaV1BasicGroup OBJECT-GROUP
       OBJECTS {
           tudaV1GeneralCycles,
           tudaV1GeneralVersionInfo,
           tudaV1SyncTokenCycles,
           tudaV1SyncTokenData,
           tudaV1RestrictCycles,
           tudaV1RestrictData,
           tudaV1VerifyTokenCycles,
           tudaV1VerifyTokenData
       }
       STATUS  current
       DESCRIPTION
           "The basic mandatory TUDA MIB objects."
       ::= { tudaV1ObjectGroups 1 }

   tudaV1OptionalGroup OBJECT-GROUP
       OBJECTS {
           tudaV1AIKCertCycles,
           tudaV1AIKCertData,
           tudaV1TSACertCycles,
           tudaV1TSACertData,
           tudaV1MeasureCycles,
           tudaV1MeasureInstances,
           tudaV1MeasureData,



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           tudaV1SWIDTagCycles,
           tudaV1SWIDTagData
       }
       STATUS  current
       DESCRIPTION
           "The optional TUDA MIB objects."
       ::= { tudaV1ObjectGroups 2 }

   tudaV1TrapGroup NOTIFICATION-GROUP
       NOTIFICATIONS { tudaV1TrapV2Cycles }
       STATUS      current
       DESCRIPTION
           "The recommended TUDA MIB traps - notifications."
       ::= { tudaV1NotificationGroups 1 }

   END
   <CODE ENDS>

5.  IANA Considerations

   This memo includes requests to IANA, including registrations for
   media type definitions.

   TBD

6.  Security Considerations

   There are Security Considerations.  TBD

7.  Acknowledgements

8.  Change Log

   Changes from version 00 to version 01:

   Major update to the SNMP MIB and added a table for the Concise SWID
   profile Reference Hashes that provides additional information to be
   compared with the measurement logs.

9.  Contributors

   TBD

10.  References







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10.1.  Normative References

   [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>.

10.2.  Informative References

   [AIK-Credential]
              "TCG Credential Profile", 2007,
              <http://www.trustedcomputinggroup.org/files/
              temp/642686EC-1D09-3519-AD58BB4C50BD5028/
              IWG%20Credential_Profiles_V1_R1_14.pdf>.

   [AIK-Enrollment]
              TCG Infrastructure Working Group, "A CMC Profile for AIK
              Certificate Enrollment", 2011,
              <https://www.trustedcomputinggroup.org/files/
              resource_files/738DF0BB-1A4B-B294-D0AF6AF9CC023163/
              IWG_CMC_Profile_Cert_Enrollment_v1_r7.pdf>.

   [I-D-birkholz-sacm-coswid]
              Birkholz, H., Fitzgerald-McKay, J., Schmidt, C., and D.
              Waltermire, "Concise Software Identifiers", draft-
              birkholz-sacm-coswid-00 (work in progress), March 2016.

   [I-D.greevenbosch-appsawg-cbor-cddl]
              Vigano, C. and H. Birkholz, "CBOR data definition language
              (CDDL): a notational convention to express CBOR data
              structures", draft-greevenbosch-appsawg-cbor-cddl-08 (work
              in progress), March 2016.

   [I-D.ietf-netconf-restconf]
              Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", draft-ietf-netconf-restconf-10 (work in
              progress), March 2016.

   [IEEE802.1AR]
              IEEE Computer Society, "IEEE Standard for Local and
              metropolitan area networks -- Secure Device Identity",
              IEEE Std 802.1AR, 2009.

   [MTAF]     Fuchs, A., "Improving Scalability for Remote Attestation",
              Master Thesis (Diplomarbeit), Technische Universitaet
              Darmstadt, Germany, 2008.





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   [PTS]      "TCG Attestation PTS Protocol Binding to TNC IF-M", 2011,
              <http://www.trustedcomputinggroup.org/files/
              resource_files/508E7E89-1A4B-B294-D06395D5FD7EC4E7/
              IFM_PTS_v1_0_r28.pdf>.

   [REST]     Fielding, R., "Architectural Styles and the Design of
              Network-based Software Architectures", Ph.D. Dissertation,
              University of California, Irvine, 2000,
              <http://www.ics.uci.edu/~fielding/pubs/dissertation/
              fielding_dissertation.pdf>.

   [RFC1213]  McCloghrie, K. and M. Rose, "Management Information Base
              for Network Management of TCP/IP-based internets: MIB-II",
              STD 17, RFC 1213, DOI 10.17487/RFC1213, March 1991,
              <http://www.rfc-editor.org/info/rfc1213>.

   [RFC2790]  Waldbusser, S. and P. Grillo, "Host Resources MIB",
              RFC 2790, DOI 10.17487/RFC2790, March 2000,
              <http://www.rfc-editor.org/info/rfc2790>.

   [RFC3161]  Adams, C., Cain, P., Pinkas, D., and R. Zuccherato,
              "Internet X.509 Public Key Infrastructure Time-Stamp
              Protocol (TSP)", RFC 3161, DOI 10.17487/RFC3161, August
              2001, <http://www.rfc-editor.org/info/rfc3161>.

   [RFC3411]  Harrington, D., Presuhn, R., and B. Wijnen, "An
              Architecture for Describing Simple Network Management
              Protocol (SNMP) Management Frameworks", STD 62, RFC 3411,
              DOI 10.17487/RFC3411, December 2002,
              <http://www.rfc-editor.org/info/rfc3411>.

   [RFC3418]  Presuhn, R., Ed., "Management Information Base (MIB) for
              the Simple Network Management Protocol (SNMP)", STD 62,
              RFC 3418, DOI 10.17487/RFC3418, December 2002,
              <http://www.rfc-editor.org/info/rfc3418>.

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
              <http://www.rfc-editor.org/info/rfc4949>.

   [RFC6690]  Shelby, Z., "Constrained RESTful Environments (CoRE) Link
              Format", RFC 6690, DOI 10.17487/RFC6690, August 2012,
              <http://www.rfc-editor.org/info/rfc6690>.

   [RFC6933]  Bierman, A., Romascanu, D., Quittek, J., and M.
              Chandramouli, "Entity MIB (Version 4)", RFC 6933,
              DOI 10.17487/RFC6933, May 2013,
              <http://www.rfc-editor.org/info/rfc6933>.



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   [RFC7049]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
              October 2013, <http://www.rfc-editor.org/info/rfc7049>.

   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, DOI 10.17487/RFC7230, June 2014,
              <http://www.rfc-editor.org/info/rfc7230>.

   [RFC7252]  Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
              Application Protocol (CoAP)", RFC 7252,
              DOI 10.17487/RFC7252, June 2014,
              <http://www.rfc-editor.org/info/rfc7252>.

   [RFC7320]  Nottingham, M., "URI Design and Ownership", BCP 190,
              RFC 7320, DOI 10.17487/RFC7320, July 2014,
              <http://www.rfc-editor.org/info/rfc7320>.

   [RFC7540]  Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
              Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
              DOI 10.17487/RFC7540, May 2015,
              <http://www.rfc-editor.org/info/rfc7540>.

   [SFKE2008]
              Stumpf, F., Fuchs, A., Katzenbeisser, S., and C. Eckert,
              "Improving the scalability of platform attestation",
              ACM Proceedings of the 3rd ACM workshop on Scalable
              trusted computing, page 1-10, 2008.

   [STD62]    "Internet Standard 62", STD 62, RFCs 3411 to 3418,
              December 2002.

   [TPM12]    "Information technology -- Trusted Platform Module -- Part
              1: Overview", ISO/IEC 11889-1, 2009.

Appendix A.  Realization with TPM 1.2 functions

A.1.  TPM Functions

   The following TPM structures, resources and functions are used within
   this approach.  They are based upon the TPM 1.2 specification
   [TPM12].

A.1.1.  Tick-Session and Tick-Stamp

   On every boot, the TPM initializes a new Tick-Session.  Such a tick-
   session consists of a nonce that is randomly created upon each boot
   to identify the current boot-cycle - the phase between boot-time of



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   the device and shutdown or power-off - and prevent replaying of old
   tick-session values.  The TPM uses its internal entropy source that
   guarantees virtually no collisions of the nonce values between two of
   such boot cycles.

   It further includes an internal timer that is being initialize to
   Zero on each reboot.  From this point on, the TPM increments this
   timer continuously based upon its internal secure clocking
   information until the device is powered down or set to sleep.  By its
   hardware design, the TPM will detect attacks on any of those
   properties.

   The TPM offers the function TPM_TickStampBlob, which allows the TPM
   to create a signature over the current tick-session and two
   externally provided input values.  These input values are designed to
   serve as a nonce and as payload data to be included in a
   TickStampBlob: TickstampBlob := sig(TPM-key, currentTicks || nonce ||
   externalData).

   As a result, one is able to proof that at a certain point in time
   (relative to the tick-session) after the provisioning of a certain
   nonce, some certain externalData was known and provided to the TPM.
   If an approach however requires no input values or only one input
   value (such as the use in this document) the input values can be set
   to well-known value.  The convention used within TCG specifications
   and within this document is to use twenty bytes of zero
   h'0000000000000000000000000000000000000000' as well-known value.

A.1.2.  Platform Configuration Registers (PCRs)

   The TPM is a secure cryptoprocessor that provides the ability to
   store measurements and metrics about an endpoint's configuration and
   state in a secure, tamper-proof environment.  Each of these security
   relevant metrics can be stored in a volatile Platform Configuration
   Register (PCR) inside the TPM.  These measurements can be conducted
   at any point in time, ranging from an initial BIOS boot-up sequence
   to measurements taken after hundreds of hours of uptime.

   The initial measurement is triggered by the Platforms so-called pre-
   BIOS or ROM-code.  It will conduct a measurement of the first
   loadable pieces of code; i.e.\ the BIOS.  The BIOS will in turn
   measure its Option ROMs and the BootLoader, which measures the OS-
   Kernel, which in turn measures its applications.  This describes a
   so-called measurement chain.  This typically gets recorded in a so-
   called measurement log, such that the values of the PCRs can be
   reconstructed from the individual measurements for validation.





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   Via its PCRs, a TPM provides a Root of Trust that can, for example,
   support secure boot or remote attestation.  The attestation of an
   endpoint's identity or security posture is based on the content of an
   TPM's PCRs (platform integrity measurements).

A.1.3.  PCR restricted Keys

   Every key inside the TPM can be restricted in such a way that it can
   only be used if a certain set of PCRs are in a predetermined state.
   For key creation the desired state for PCRs are defined via the
   PCRInfo field inside the keyInfo parameter.  Whenever an operation
   using this key is performed, the TPM first checks whether the PCRs
   are in the correct state.  Otherwise the operation is denied by the
   TPM.

A.1.4.  CertifyInfo

   The TPM offers a command to certify the properties of a key by means
   of a signature using another key.  This includes especially the
   keyInfo which in turn includes the PCRInfo information used during
   key creation.  This way, a third party can be assured about the fact
   that a key is only usable if the PCRs are in a certain state.

A.2.  Protocol and Procedure

A.2.1.  AIK and AIK Certificate

   Attestations are based upon a cryptographic signature performed by
   the TPM using a so-called Attestation Identity Key (AIK).  An AIK has
   the properties that it cannot be exported from a TPM and is used for
   attestations.  Trust in the AIK is established by an X.509
   Certificate emitted by a Certificate Authority.  The AIK certificate
   is either provided directly or via a so-called PrivacyCA
   [AIK-Enrollment].

   This element consists of the AIK certificate that includes the AIK's
   public key used during verification as well as the certificate chain
   up to the Root CA for validation of the AIK certificate itself.

   TUDA-Cert = [AIK-Cert, TSA-Cert]; maybe split into two for SNMP
   AIK-Cert = Cert
   TSA-Cert = Cert

                    Figure 2: TUDA-Cert element in CDDL

   The TSA-Cert is a standard certificate of the TSA.





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   The AIK-Cert may be provisioned in a secure environment using
   standard means or it may follow the PrivacyCA protocols.  Figure 3
   gives a rough sketch of this protocol.  See [AIK-Enrollment] for more
   information.

   The X.509 Certificate is built from the AIK public key and the
   corresponding PKCS #7 certificate chain, as shown in Figure 3.

   Required TPM functions:

   | create_AIK_Cert(...) = {
   |   AIK = TPM_MakeIdentity()
   |   IdReq = CollateIdentityRequest(AIK,EK)
   |   IdRes = Call(AIK-CA, IdReq)
   |   AIK-Cert = TPM_ActivateIdentity(AIK, IdRes)
   | }
   |
   | /* Alternative */
   |
   | create_AIK_Cert(...) = {
   |   AIK = TPM_CreateWrapKey(Identity)
   |   AIK-Cert = Call(AIK-CA, AIK.pubkey)
   | }

                 Figure 3: Creating the TUDA-Cert element

A.2.2.  Synchronization Token

   The reference for Attestations are the Tick-Sessions of the TPM.  In
   order to put Attestations into relation with a Real Time Clock (RTC),
   it is necessary to provide a cryptographic synchronization between
   the tick session and the RTC.  To do so, a synchronization protocol
   is run with a Time Stamp Authority (TSA) that consists of three
   steps:

   o  The TPM creates a TickStampBlob using the AIK

   o  This TickstampBlob is used as nonce to the Timestamp of the TSA

   o  Another TickStampBlob with the AIK is created using the TSA's
      Timestamp a nonce

   The first TickStampBlob is called "left" and the second "right" in a
   reference to their position on a time-axis.

   These three elements, with the TSA's certificate factored out, form
   the synchronization token




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   TUDA-Synctoken = [
     left: TickStampBlob-Output,
     timestamp: TimeStampToken,
     right: TickStampBlob-Output,
   ]

   TimeStampToken = bytes ; RFC 3161

   TickStampBlob-Output = [
     currentTicks: TPM-CURRENT-TICKS,
     sig: bytes,
   ]

   TPM-CURRENT-TICKS = [
     currentTicks: uint
     ? (
       tickRate: uint
       tickNonce: TPM-NONCE
     )
   ]
   ; Note that TickStampBlob-Output "right" can omit the values for
   ;   tickRate and tickNonce since they are the same as in "left"

   TPM-NONCE = bytes .size 20

                    Figure 4: TUDA-Sync element in CDDL

   Required TPM functions:























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   | dummyDigest = h'0000000000000000000000000000000000000000'
   | dummyNonce = dummyDigest
   |
   | create_sync_token(AIKHandle, TSA) = {
   |   ts_left = TPM_TickStampBlob(
   |       keyHandle = AIK_Handle,      /*TPM_KEY_HANDLE*/
   |       antiReplay = dummyNonce,     /*TPM_NONCE*/
   |       digestToStamp = dummyDigest  /*TPM_DIGEST*/)
   |
   |   ts = TSA_Timestamp(TSA, nonce = hash(ts_left))
   |
   |   ts_right = TPM_TickStampBlob(
   |       keyHandle = AIK_Handle,      /*TPM_KEY_HANDLE*/
   |       antiReplay = dummyNonce,     /*TPM_NONCE*/
   |       digestToStamp = hash(ts))    /*TPM_DIGEST*/
   |
   |   TUDA-SyncToken = [[ts_left.ticks, ts_left.sig], ts,
   |                     [ts_right.ticks.currentTicks, ts_right.sig]]
   |   /* Note: skip the nonce and tickRate field for ts_right.ticks */
   | }


                 Figure 5: Creating the Sync-Token element

A.2.3.  RestrictionInfo

   The attestation relies on the capability of the TPM to operate on
   restricted keys.  Whenever the PCR values for the machine to be
   attested change, a new restricted key is created that can only be
   operated as long as the PCRs remain in their current state.

   In order to prove to the Verifier that this restricted temporary key
   actually has these properties and also to provide the PCR value that
   it is restricted, the TPM command TPM_CertifyInfo is used.  It
   creates a signed certificate using the AIK about the newly created
   restricted key.

   This token is formed from the list of:

   o  PCR list,

   o  the newly created restricted public key, and

   o  the certificate.

 TUDA-RestrictionInfo = [Composite,
                         restrictedKey_Pub: Pubkey,
                         TPM-CERTIFY-INFO]



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 PCRSelection = bytes .size (2..4) ; used as bit string

 Composite = [
   bitmask: PCRSelection,
   values: [*PCR-Hash],
 ]

 Pubkey = bytes ; do we need to expose structure here?

 TPM-CERTIFY-INFO = [
   ; we don't encode TPM-STRUCT-VER:
   ; these are 4 bytes always equal to h'01010000'
   keyUsage: uint, ; 4byte? 2byte?
   keyFlags: bytes .size 4, ; 4byte
   authDataUsage: uint, ; 1byte (enum)
   algorithmParms: TPM-KEY-PARMS,
   pubkeyDigest: Hash,
   ; we don't encode TPM-NONCE data, which is 20 bytes, all zero
   parentPCRStatus: bool,
   ; no need to encode pcrinfosize
   pcrinfo: TPM-PCR-INFO,        ; we have exactly one
 ]

 TPM-PCR-INFO = [
     pcrSelection: PCRSelection; /* TPM_PCR_SELECTION */
     digestAtRelease: PCR-Hash;  /* TPM_COMPOSITE_HASH */
     digestAtCreation: PCR-Hash; /* TPM_COMPOSITE_HASH */
 ]

 TPM-KEY-PARMS = [
   ; algorithmID: uint, ; <= 4 bytes -- not encoded, constant for TPM1.2
   encScheme: uint, ; <= 2 bytes
   sigScheme: uint, ; <= 2 bytes
   parms: TPM-RSA-KEY-PARMS,
 ]

 TPM-RSA-KEY-PARMS = [
   ; "size of the RSA key in bits":
   keyLength: uint
   ; "number of prime factors used by this RSA key":
   numPrimes: uint
   ; "This SHALL be the size of the exponent":
   exponentSize: null / uint / biguint
   ; "If the key is using the default exponent then the exponentSize
   ; MUST be 0" -> we represent this case as null
 ]





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                    Figure 6: TUDA-Key element in CDDL

   Required TPM functions:

   | dummyDigest = h'0000000000000000000000000000000000000000'
   | dummyNonce = dummyDigest
   |
   | create_Composite
   |
   | create_restrictedKey_Pub(pcrsel) = {
   |   PCRInfo = {pcrSelection = pcrsel,
   |              digestAtRelease = hash(currentValues(pcrSelection))
   |              digestAtCreation = dummyDigest}
   |   / * PCRInfo is a TPM_PCR_INFO and thus also a TPM_KEY */
   |
   |   wk = TPM_CreateWrapKey(keyInfo = PCRInfo)
   |   wk.keyInfo.pubKey
   | }
   |
   | create_TPM-Certify-Info = {
   |   CertifyInfo = TPM_CertifyKey(
   |       certHandle = AIK,          /* TPM_KEY_HANDLE */
   |       keyHandle = wk,            /* TPM_KEY_HANDLE */
   |       antiReply = dummyNonce)    /* TPM_NONCE */
   |
   |   CertifyInfo.strip()
   |   /* Remove those values that are not needed */
   | }

                       Figure 7: Creating the pubkey

A.2.4.  Measurement Log

   Similarly to regular attestations, the Verifier needs a way to
   reconstruct the PCRs' values in order to estimate the trustworthiness
   of the device.  As such, a list of those elements that were extended
   into the PCRs is reported.  Note though that for certain
   environments, this step may be optional if a list of valid PCR
   configurations exists and no measurement log is required.












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   TUDA-Measurement-Log = [*PCR-Event]
   PCR-Event = [
     type: PCR-Event-Type,
     pcr: uint,
     template-hash: PCR-Hash,
     filedata-hash: tagged-hash,
     pathname: text; called filename-hint in ima (non-ng)
   ]

   PCR-Event-Type = &(
     bios: 0
     ima: 1
     ima-ng: 2
   )

   ; might want to make use of COSE registry here
   ; however, that might never define a value for sha1
   tagged-hash /= [sha1: 0, bytes .size 20]
   tagged-hash /= [sha256: 1, bytes .size 32]

A.2.5.  Implicit Attestation

   The actual attestation is then based upon a TickStampBlob using the
   restricted temporary key that was certified in the steps above.  The
   TPM-Tickstamp is executed and thereby provides evidence that at this
   point in time (with respect to the TPM internal tick-session) a
   certain configuration existed (namely the PCR values associated with
   the restricted key).  Together with the synchronization token this
   tick-related timing can then be related to the real-time clock.

   This element consists only of the TPM_TickStampBlock with no nonce.

   TUDA-Verifytoken = TickStampBlob-Output

                   Figure 8: TUDA-Verify element in CDDL

   Required TPM functions:

   | imp_att = TPM_TickStampBlob(
   |     keyHandle = restrictedKey_Handle,     /*TPM_KEY_HANDLE*/
   |     antiReplay = dummyNonce,              /*TPM_NONCE*/
   |     digestToStamp = dummyDigest)          /*TPM_DIGEST*/
   |
   | VerifyToken = imp_att

                    Figure 9: Creating the Verify Token





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A.2.6.  Attestation Verification Approach

   The seven TUDA information elements transport the essential content
   that is required to enable verification of the attestation statement
   at the Verifier.  The following listings illustrate the verification
   algorithm to be used at the Verifier in pseudocode.  The pseudocode
   provided covers the entire verification task.  If only a subset of
   TUDA elements changed (see Section 2.1), only the corresponding code
   listings need to be re-executed.

   | TSA_pub = verifyCert(TSA-CA, Cert.TSA-Cert)
   | AIK_pub = verifyCert(AIK-CA, Cert.AIK-Cert)

                  Figure 10: Verification of Certificates

  | ts_left = Synctoken.left
  | ts_right = Synctoken.right
  |
  | /* Reconstruct ts_right's omitted values; Alternatively assert == */
  | ts_right.currentTicks.tickRate = ts_left.currentTicks.tickRate
  | ts_right.currentTicks.tickNonce = ts_left.currentTicks.tickNonce
  |
  | ticks_left = ts_left.currentTicks
  | ticks_right = ts_right.currentTicks
  |
  | /* Verify Signatures */
  | verifySig(AIK_pub, dummyNonce || dummyDigest || ticks_left)
  | verifySig(TSA_pub, hash(ts_left) || timestamp.time)
  | verifySig(AIK_pub, dummyNonce || hash(timestamp) || ticks_right)
  |
  | delta_left = timestamp.time -
  |     ticks_left.currentTicks * ticks_left.tickRate / 1000
  |
  | delta_right = timestamp.time -
  |     ticks_right.currentTicks * ticks_right.tickRate / 1000

             Figure 11: Verification of Synchronization Token














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   | compositeHash = hash_init()
   | for value in Composite.values:
   |     hash_update(compositeHash, value)
   | compositeHash = hash_finish(compositeHash)
   |
   | certInfo = reconstruct_static(TPM-CERTIFY-INFO)
   |
   | assert(Composite.bitmask == ExpectedPCRBitmask)
   | assert(certInfo.pcrinfo.PCRSelection == Composite.bitmask)
   | assert(certInfo.pcrinfo.digestAtRelease == compositeHash)
   | assert(certInfo.pubkeyDigest == hash(restrictedKey_Pub))
   |
   | verifySig(AIK_pub, dummyNonce || certInfo)

                Figure 12: Verification of Restriction Info

   | for event in Measurement-Log:
   |     if event.pcr not in ExpectedPCRBitmask:
   |         continue
   |     if event.type == BIOS:
   |         assert_whitelist-bios(event.pcr, event.template-hash)
   |     if event.type == ima:
   |         assert(event.pcr == 10)
   |         assert_whitelist(event.pathname, event.filedata-hash)
   |         assert(event.template-hash ==
   |                hash(event.pathname || event.filedata-hash))
   |     if event.type == ima-ng:
   |         assert(event.pcr == 10)
   |         assert_whitelist-ng(event.pathname, event.filedata-hash)
   |         assert(event.template-hash ==
   |                hash(event.pathname || event.filedata-hash))
   |
   |     virtPCR[event.pcr] = hash_extend(virtPCR[event.pcr],
   |                                      event.template-hash)
   |
   | for pcr in ExpectedPCRBitmask:
   |     assert(virtPCR[pcr] == Composite.values[i++]

                Figure 13: Verification of Measurement Log












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  | ts = Verifytoken
  |
  | /* Reconstruct ts's omitted values; Alternatively assert == */
  | ts.currentTicks.tickRate = ts_left.currentTicks.tickRate
  | ts.currentTicks.tickNonce = ts_left.currentTicks.tickNonce
  |
  | verifySig(restrictedKey_pub, dummyNonce || dummyDigest || ts)
  |
  | ticks = ts.currentTicks
  |
  | time_left = delta_right + ticks.currentTicks * ticks.tickRate / 1000
  | time_right = delta_left + ticks.currentTicks * ticks.tickRate / 1000
  |
  | [time_left, time_right]

               Figure 14: Verification of Attestation Token

Authors' Addresses

   Andreas Fuchs
   Fraunhofer Institute for Secure Information Technology
   Rheinstrasse 75
   Darmstadt  64295
   Germany

   Email: andreas.fuchs@sit.fraunhofer.de


   Henk Birkholz
   Fraunhofer Institute for Secure Information Technology
   Rheinstrasse 75
   Darmstadt  64295
   Germany

   Email: henk.birkholz@sit.fraunhofer.de


   Ira E McDonald
   High North Inc
   PO Box 221
   Grand Marais  49839
   US

   Email: blueroofmusic@gmail.com







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   Carsten Bormann
   Universitaet Bremen TZI
   Bibliothekstr. 1
   Bremen  D-28359
   Germany

   Phone: +49-421-218-63921
   Email: cabo@tzi.org











































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