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Versions: 00 draft-vanderstok-anima-constrained-join-proxy

anima Working Group                                        M. Richardson
Internet-Draft                                  Sandelman Software Works
Intended status: Standards Track                         P. van der Stok
Expires: April 2, 2019                            vanderstok consultancy
                                                           P. Kampanakis
                                                           Cisco Systems
                                                      September 29, 2018


           Constrained Join Proxy for Bootstrapping Protocols
         draft-vanderstok-constrained-anima-dtls-join-proxy-00

Abstract

   This document defines a protocol to securely assign a pledge to an
   owner, using an intermediary node between pledge and owner.  This
   intermediary node is known as a "constrained-join-proxy".

   This document extends the work of
   [I-D.ietf-anima-bootstrapping-keyinfra] by replacing the Circuit-
   proxy by a stateless constrained join-proxy, that uses IP
   encapsulation.

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 https://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 April 2, 2019.

Copyright Notice

   Copyright (c) 2018 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
   (https://trustee.ietf.org/license-info) in effect on the date of



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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   4.  Join Proxy functionality  . . . . . . . . . . . . . . . . . .   3
   5.  Join Proxy specification  . . . . . . . . . . . . . . . . . .   4
   6.  Protocol  . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   10. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     11.1.  Normative References . . . . . . . . . . . . . . . . . .   7
     11.2.  Informative References . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Enrolment of new nodes into constrained networks with constrained
   nodes present is described in [I-D.ietf-anima-bootstrapping-keyinfra]
   and makes use of Enrolment over Secure Transport (EST) [RFC7030].
   The specified solutions use https and may be too large in terms of
   code space or bandwidth required.  Constrained devices in constrained
   networks [RFC7228] typically implement the IPv6 over Low-Power
   Wireless personal Area Networks (6LoWPAN) [RFC4944] and Constrained
   Application Protocol (CoAP) [RFC7252].

   CoAP has chosen Datagram Transport Layer Security (DTLS) [RFC6347] as
   the preferred security protocol for authenticity and confidentiality
   of the messages.  A constrained version of EST, using Coap and DTLS,
   is described in [I-D.ietf-ace-coap-est].

   DTLS is a client-server protocol relying on the underlying IP layer
   to perform the routing between the DTLS Client and the DTLS Server.
   However, the new "joining" device will not be IP routable until it is
   authenticated to the network.  A new "joining" device can only
   initially use a link-local IPv6 address to communicate with a
   neighbour node using neighbour discovery [RFC6775] until it receives
   the necessary network configuration parameters.  However, before the
   device can receive these configuration parameters, it needs to



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   authenticate itself to the network to which it connects.  In
   [I-D.ietf-anima-bootstrapping-keyinfra] Enrolment over Secure
   Transport (EST) [RFC7030] is used to authenticate the joining device.
   However, IPv6 routing is necessary to establish a connection between
   joining device and the EST server.

   This document specifies a Join-proxy and protocol to act as
   intermediary between joining device and EST server to establish a
   connection between joining device and EST server.

   This document is very much inspired by text published earlier in
   [I-D.kumar-dice-dtls-relay].

2.  Terminology

   The following terms are defined in [RFC8366], and are used
   identically as in that document: artifact, imprint, domain, Join
   Registrar/Coordinator (JRC), Manufacturer Authorized Signing
   Authority (MASA), pledge, Trust of First Use (TOFU), and Voucher.

3.  Requirements Language

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119
   [RFC2119] and indicate requirement levels for compliant STuPiD
   implementations.

4.  Join Proxy functionality

   As depicted in the Figure 1, the joining Device, or pledge (P), is
   more than one hop away from the EST server (E) and not yet
   authenticated into the network.  At this stage, it can only
   communicate one-hop to its nearest neighbour, the Join proxy (J)
   using their link-local IPv6 addresses.  However, the Device needs to
   communicate with end-to-end security with a Registrar hosting the EST
   server (E) to authenticate and get the relevant system/network
   parameters.  If the Pledge (P) initiates a DTLS connection to the EST
   server whose IP address has been pre-configured, then the packets are
   dropped at the Join Proxy (J) since the Pledge (P) is not yet
   admitted to the network or there is no IP routability to Pledge (P)
   for any returned messages.









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                         ++++
                         |E |----       +--+        +--+
                         |  |    \      |J |........|P |
                         ++++     \-----|  |        |  |
                      EST server        +--+        +--+
                      REgistrar       Join Proxy   PLedge
                                                   "Joining" Device


                      Figure 1: multi-hop enrolment.

   Furthermore, the Pledge (P) may wish to establish a secure connection
   to the EST server (E) in the network assuming appropriate credentials
   are exchanged out-of-band, e.g. a hash of the Pledge (P)'s raw public
   key could be provided to the EST server (E).  However, the Pledge (P)
   is unaware of the IP address of the EST-server (E) to initiate a DTLS
   connection and perform authentication with.

   An DTLS connection is required between Pledge and EST server.  To
   overcome the problems with non-routability of DTLS packets and/ or
   discovery of the destination address of the EST Server to contact,
   the Join Proxy is introduced.  This Join-Proxy functionality is
   configured into all authenticated devices in the network which may
   act as the Join Proxy (J) for newly joining nodes.  The Join Proxy
   allows for routing of the packets from the Pledge (P) using IP
   routing to the intended EST Server.

5.  Join Proxy specification

   In this section, the constrained Join Proxy functionality is
   specified using DTLS and coaps.  When a joining device as a client
   attempts a DTLS connection to the EST server, it uses its link- local
   IP address as its IP source address.  This message is transmitted
   one-hop to a neighbour node.  Under normal circumstances, this
   message would be dropped at the neighbour node since the joining
   device is not yet IP routable or it is not yet authenticated to send
   messages through the network.  However, if the neighbour device has
   the Join Proxy functionality enabled, it routes the DTLS message to a
   specific EST Server.  Additional security mechanisms need to exist to
   prevent this routing functionality being used by rogue nodes to
   bypass any network authentication procedures.

   The Join-proxy is stateless to minimize the requirements on the
   constrained Join-proxy device.

   If an untrusted DTLS Client that can only use link-local addressing
   wants to contact a trusted end-point EST Server, it sends the DTLS
   message to the Join Proxy.  The Join Proxy encapsulates this message



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   into a new type of message called Join ProxY (JPY) message.  The JPY
   message consists of two parts:

   o  Header (H) field: consisting of the source link-local address and
      port of the DTLS Client device, and

   o  Contents (C) field: containing the original DTLS message.

   On receiving the JPY message, the EST Server decapsulates it to
   retrieve the two parts.  It uses the Header field information to
   transiently store the DTLS Client's address and port.  The EST Server
   then performs the normal DTLS operations on the DTLS message from the
   Contents field.  However, when the EST Server replies, it also
   encapsulates its DTLS message in a JPY message back to the Join
   Proxy.  The Header contains the original source link-local address
   and port of the DTLS Client from the transient state stored earlier
   (which can now be discarded) and the Contents field contains the DTLS
   message.

   On receiving the JPY message, the Join Proxy decapsulates it to
   retrieve the two parts.  It uses the Header field to route the DTLS
   message retrieved from the Contents field to the joining node.

   The Figure 2 depicts the message flow diagram when the EST Server
   end-point address is known only to the Join Proxy:


























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   +--------------+------------+---------------+-----------------------+
   | EST  Client  | Join Proxy |    EST server |        Message        |
   |     (P)      |     (J)    |      (E)      |Src_IP:port|Dst_IP:port|
   +--------------+------------+---------------+-----------+-----------+
   |      --ClientHello-->                     | IP_C:p_C  |IP_Ra:5684 |
   |                    --JPY[H(IP_C:p_C),-->  | IP_Rb:p_Rb|IP_S:5684  |
   |                          C(ClientHello)]  |           |           |
   |                    <--JPY[H(IP_C:p_C),--  | IP_S:5684 |IP_Rb:p_Rb |
   |                         C(ServerHello)]   |           |           |
   |      <--ServerHello--                     | IP_Ra:5684|IP_C:p_C   |
   |              :                            |           |           |
   |              :                            |     :     |    :      |
   |                                           |     :     |    :      |
   |      --Finished-->                        | IP_C:p_C  |IP_Ra:5684 |
   |                    --JPY[H(IP_C:p_C),-->  | IP_Rb:p_Rb|IP_S:5684  |
   |                          C(Finished)]     |           |           |
   |                    <--JPY[H(IP_C:p_C),--  | IP_S:5684 |IP_Rb:p_Rb |
   |                         C(Finished)]      |           |           |
   |      <--Finished--                        | IP_Ra:5684|IP_C:p_C   |
   |              :                            |     :     |    :      |
   +-------------------------------------------+-----------+-----------+
   IP_C:p_C = Link-local IP address and port of DTLS Client
   IP_S:5684 = IP address and coaps port of DTLS Server
   IP_Ra:5684 = Link-local IP address and coaps port of DTLS Relay
   IP_Rb:p_Rb = IP address(can be same as IP_Ra) and port of DTLS Relay

   JPY[H(),C()] = Join Proxy message with header H and content C


                Figure 2: constrained joining message flow.

6.  Protocol

   The JPY message is constructed as a single untagged [RFC7049] CBOR
   map.  The contents of the map include:

   1: the pledge IPv6 Link Local address as a 16-byte binary value.

   2: the pledge's UDP port number, if different from 5684, as a CBOR
      integer.

   3: the proxy's ifindex or other identifier for the physical port on
      which the pledge is connected.

   4: the contents of the UDP (DTLS) message received from the pledge.

   (INSERT CDDL notation)




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7.  Security Considerations

   It should be noted here that the contents of the CBOR map are not
   protected, but that the communication is between the Proxy and a
   known registrar (a connected UDP socket), and that messages from
   other origins are ignored.

8.  IANA Considerations

   This document needs to create a registry for key indexes in the CBOR
   map.  It should be given a name, and the amending formula should be
   IETF Specification.

9.  Acknowledgements

   Much of this text is inspired by [I-D.kumar-dice-dtls-relay].

10.  Changelog

   empty

11.  References

11.1.  Normative References

   [I-D.ietf-ace-cbor-web-token]
              Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
              "CBOR Web Token (CWT)", draft-ietf-ace-cbor-web-token-15
              (work in progress), March 2018.

   [I-D.ietf-ace-coap-est]
              Stok, P., Kampanakis, P., Kumar, S., Richardson, M.,
              Furuhed, M., and S. Raza, "EST over secure CoAP (EST-
              coaps)", draft-ietf-ace-coap-est-05 (work in progress),
              July 2018.

   [I-D.ietf-anima-bootstrapping-keyinfra]
              Pritikin, M., Richardson, M., Behringer, M., Bjarnason,
              S., and K. Watsen, "Bootstrapping Remote Secure Key
              Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
              keyinfra-16 (work in progress), June 2018.

   [I-D.ietf-core-object-security]
              Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
              "Object Security for Constrained RESTful Environments
              (OSCORE)", draft-ietf-core-object-security-15 (work in
              progress), August 2018.




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   [ieee802-1AR]
              IEEE Standard, ., "IEEE 802.1AR Secure Device Identifier",
              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>.

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

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
              January 2012, <https://www.rfc-editor.org/info/rfc6347>.

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

   [RFC7250]  Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J.,
              Weiler, S., and T. Kivinen, "Using Raw Public Keys in
              Transport Layer Security (TLS) and Datagram Transport
              Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250,
              June 2014, <https://www.rfc-editor.org/info/rfc7250>.

   [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>.

   [RFC8152]  Schaad, J., "CBOR Object Signing and Encryption (COSE)",
              RFC 8152, DOI 10.17487/RFC8152, July 2017,
              <https://www.rfc-editor.org/info/rfc8152>.

   [RFC8366]  Watsen, K., Richardson, M., Pritikin, M., and T. Eckert,
              "A Voucher Artifact for Bootstrapping Protocols",
              RFC 8366, DOI 10.17487/RFC8366, May 2018,
              <https://www.rfc-editor.org/info/rfc8366>.

11.2.  Informative References

   [duckling]
              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>.



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   [I-D.kumar-dice-dtls-relay]
              Kumar, S., Keoh, S., and O. Garcia-Morchon, "DTLS Relay
              for Constrained Environments", draft-kumar-dice-dtls-
              relay-02 (work in progress), October 2014.

   [pledge]   Dictionary.com, ., "Dictionary.com Unabridged", 2015,
              <http://dictionary.reference.com/browse/pledge>.

   [RFC4944]  Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
              "Transmission of IPv6 Packets over IEEE 802.15.4
              Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
              <https://www.rfc-editor.org/info/rfc4944>.

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

   [RFC6775]  Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
              Bormann, "Neighbor Discovery Optimization for IPv6 over
              Low-Power Wireless Personal Area Networks (6LoWPANs)",
              RFC 6775, DOI 10.17487/RFC6775, November 2012,
              <https://www.rfc-editor.org/info/rfc6775>.

   [RFC7030]  Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
              "Enrollment over Secure Transport", RFC 7030,
              DOI 10.17487/RFC7030, October 2013,
              <https://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,
              <https://www.rfc-editor.org/info/rfc7228>.

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

Authors' Addresses

   Michael Richardson
   Sandelman Software Works

   Email: mcr+ietf@sandelman.ca







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   Peter van der Stok
   vanderstok consultancy

   Email: consultancy@vanderstok.org


   Panos Kampanakis
   Cisco Systems

   Email: pkampana@cisco.com









































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