Skip to main content

OSCOAP profile of ACE
draft-seitz-ace-oscoap-profile-03

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
Authors Ludwig Seitz , Martin Gunnarsson , Francesca Palombini
Last updated 2017-06-30 (Latest revision 2017-05-03)
Replaces draft-seitz-ace-ocsoap-profile
Replaced by draft-ietf-ace-oscore-profile, draft-ietf-ace-oscore-profile, RFC 9203
RFC stream (None)
Formats
Additional resources
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date (None)
Responsible AD (None)
Send notices to (None)
draft-seitz-ace-oscoap-profile-03
ACE Working Group                                               L. Seitz
Internet-Draft                                             M. Gunnarsson
Intended Status: Standards Track                            RISE SICS AB
Expires: January 1, 2018                                    F. Palombini
                                                             Ericsson AB
                                                           June 30, 2017

                         OSCOAP profile of ACE
                   draft-seitz-ace-oscoap-profile-03

Abstract

   This memo specifies a profile for the ACE framework for
   Authentication and Authorization.  It utilizes Object Security of
   CoAP (OSCOAP) and Ephemeral Diffie-Hellman over COSE (EDHOC) to
   provide communication security, server authentication, and proof-of-
   possession for a key owned by the client and bound to an OAuth 2.0
   access token.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   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".

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

Copyright and License Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

 

Seitz, L.               Expires January 1, 2018                 [Page 1]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

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

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1  Terminology . . . . . . . . . . . . . . . . . . . . . . . .  3
   2. Client to Resource Server . . . . . . . . . . . . . . . . . . .  4
     2.1. Signaling the use of OSCOAP . . . . . . . . . . . . . . . .  4
     2.2. Key establishment for OSCOAP  . . . . . . . . . . . . . . .  4
       2.2.1 Using the pop-key with OSCOAP directly (OSCOAP)  . . . .  4
       2.2.1 Using the pop-key with EDHOC (EDHOC+OSCOAP)  . . . . . .  7
   3. Client to Authorization Server  . . . . . . . . . . . . . . . . 12
   4. Resource Server to Authorization Server . . . . . . . . . . . . 12
   5. Security Considerations . . . . . . . . . . . . . . . . . . . . 13
   6. Privacy Considerations  . . . . . . . . . . . . . . . . . . . . 13
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 13
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     9.1  Normative References  . . . . . . . . . . . . . . . . . . . 13
     9.2  Informative References  . . . . . . . . . . . . . . . . . . 14
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 14

 

Seitz, L.               Expires January 1, 2018                 [Page 2]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

1.  Introduction

   This memo specifies a profile of the ACE framework [I-D.ietf-ace-
   oauth-authz].  In this profile, a client and a resource server use
   CoAP [RFC7252] to communicate.  The client uses an access token,
   bound to a key (the proof-of-possession key) to authorize its access
   to the resource server.  In order to provide communication security,
   proof of possession, and server authentication they use Object
   Security of CoAP (OSCOAP) [I-D.ietf-core-object-security] and
   Ephemeral Diffie-Hellman Over COSE (EDHOC) [I-D.selander-ace-cose-
   ecdhe].  Optionally the client and the resource server may also use
   CoAP and OSCOAP to communicate with the authorization server.  The
   use of EDHOC in this profile in addition to OSCOAP, provides perfect
   forward secrecy (PFS) and the initial proof-of-possession, which ties
   the proof-of-possession key to an OSCOAP security context.

   OSCOAP specifies how to use CBOR Object Signing and Encryption (COSE)
   [I-D.ietf-cose-msg] to secure CoAP messages.  In order to provide
   replay and reordering protection OSCOAP also introduces sequence
   numbers that are used together with COSE.  EDHOC specifies an
   authenticated Diffie-Hellman protocol that allows two parties to use
   CBOR [RFC7049] and COSE in order to establish a shared secret key
   with perfect forward secrecy.

1.1  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].  These
   words may also appear in this document in lowercase, absent their
   normative meanings.

   Certain security-related terms such as "authentication",
   "authorization", "confidentiality", "(data) integrity", "message 
   authentication code", and "verify" are taken from [RFC4949].

   Since we describe exchanges as RESTful protocol interactions HTTP
   [RFC7231] offers useful terminology.

   Terminology for entities in the architecture is defined in OAuth 2.0
   [RFC6749] and [I-D.ietf-ace-actors], such as client (C), resource
   server (RS), and authorization server (AS).

   Note that the term "endpoint" is used here following its OAuth
   definition, which is to denote resources such as /token and
   /introspect at the AS and /authz-info at the RS.  The CoAP [RFC7252]
   definition, which is "An entity participating in the CoAP protocol"
   is not used in this memo.
 

Seitz, L.               Expires January 1, 2018                 [Page 3]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

2. Client to Resource Server

   The use of OSCOAP for arbitrary CoAP messages is specified in [I-
   D.ietf-core-object-security].  This section defines the specific uses
   and their purpose for securing the communication between a client and
   a resource server, and the parameters needed to negotiate the use of
   this profile with the token endpoint at the authorization server as
   specified in section 5.5 of the ACE framework [I-D.ietf-ace-oauth-
   authz].

2.1. Signaling the use of OSCOAP

   A client requests a token at an AS via the /token endpoint.  This
   follows the message formats specified in section 5.5.1 of the ACE
   framework [I-D.ietf.ace-oauth-authz].

   The AS responding to a successful access token request as defined in
   section 5.5.2 of the ACE framework can signal that the use of OSCOAP
   is REQUIRED for a specific access token by including the "profile"
   parameter with the value "coap_oscoap" in the access token response. 
   This means that the client MUST use OSCOAP towards all resource
   servers for which this access token is valid.

   The error response procedures defined in section 5.5.3 of the ACE
   framework are unchanged by this profile.

   Note the the client and the authorization server MAY OPTIONALLY use
   OSCOAP to protect the interaction via the /token endpoint. See
   section 3 for details.

2.2. Key establishment for OSCOAP

   Section 3.2 of OSCOAP [I-D.ietf-core-object-security] defines how to
   derive a security context based on a symmetric master secret and a
   few other parameters, established between client and server.  The
   proof-of-possession key (pop-key) provisioned from the AS MAY, in
   case of pre-shared keys, be used directly as master secret in OSCOAP.
    Alternatively the pop-key (symmetric or asymmetric) MAY be used to
   authenticate the messages in the key exchange protocol EDHOC [I-
   D.selander-ace-cose-ecdhe], from which a master secret is derived.

2.2.1 Using the pop-key with OSCOAP directly (OSCOAP)

   If OSCOAP is used directly with the symmetric pop-key as master
   secret, then the AS MUST provision the following data, in response to
   the access token request:

      o  a symmetric key (pop-key)
 

Seitz, L.               Expires January 1, 2018                 [Page 4]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

      o  the sender identifier
      o  the recipient identifier

   Additionally, the AS MAY provision the following data, in the same
   response.  In case these parameters are omitted, the default values
   are used as described in section 3.2. of [I-D.ietf-core-object-
   security].

      o  an AEAD algorithm
      o  a KDF algorithm
      o  a salt

   The pop-key MUST be communicated as COSE_Key in the 'cnf' parameter
   of the access token response as defined in section 5.5.4.5 of [I-
   D.ietf-ace-oauth-authz].  The AEAD algorithm MAY be included as the
   'alg' parameter in the COSE_Key; the KDF algorithm MAY be included as
   the 'kdf' parameter of the COSE_Key and the salt MAY be included as
   the 'slt' parameter of the COSE_Key as defined in table 1.  The same
   parameters MUST be included as metadata of the access token, if the
   token is a CWT [I-D.ietf-ace-cbor-web-token], the same COSE_Key
   structure MUST be placed in the 'cnf' claim of this token. The AS
   MUST also assign identifiers to both client and RS, which are then
   used as Sender ID and Recipient ID in the OSCOAP context as described
   in section 3.1. of [I-D.ietf-core-object-security].  These MUST be
   included in the COSE_Key as header parameters, as defined in table 1.
    As suggested in section 3.3 of [I-D.ietf-core-object-security], it
   is RECOMMENDED that the AS use pseudo-random 64-bit long IDs, so that
   the probability of collisions is negligible.

   Note that C should receive the client id as 'sid' and the RS id as
   'rid', while the RS should receive the RS id as 'sid' and the client
   id as 'rid'.

   +---------+-------+----------------+------------+-------------------+
   | name    | label | CBOR type      | registry   | description       |
   +---------+-------+----------------+------------+-------------------+
   | sid     | TBD   | bstr           |            | Identifies the    |
   |         |       |                |            | sender in an      |
   |         |       |                |            | OSCOAP context    |
   |         |       |                |            | using this key    |
   |         |       |                |            |                   |
   | rid     | TBD   | bstr           |            | Identifies the    |
   |         |       |                |            | recipient in an   |
   |         |       |                |            | OSCOAP context    |
   |         |       |                |            | using this key    |
   |         |       |                |            |                   |
   | kdf     | TBD   | bstr           |            | Identifies the    |
 

Seitz, L.               Expires January 1, 2018                 [Page 5]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

   |         |       |                |            | KDF algorithm in  |
   |         |       |                |            | an OSCOAP context |
   |         |       |                |            | using this key    |
   |         |       |                |            |                   |
   | slt     | TBD   | bstr           |            | Identifies the    |
   |         |       |                |            | master salt in    |
   |         |       |                |            | an OSCOAP context |
   |         |       |                |            | using this key    |
   +---------+-------+----------------+------------+-------------------+
           Table 1: Additional common header parameters for COSE_Key 

   Figure 1 shows an example of such an AS response, in CBOR diagnostic
   notation without the tag and value abbreviations.

       Header: Created (Code=2.01)
         Content-Type: "application/cose+cbor"
         Payload:
         {
           "access_token" : b64'SlAV32hkKG ...
            (remainder of access token omitted for brevity)',
           "profile" : "coap_oscoap",
           "expires_in" : "3600",
           "cnf" : {
             "COSE_Key" : {
               "kty" : "Symmetric",
               "alg" : "AES-CCM-16-64-128",
               "sid" : b64'qA',
               "rid" : b64'Qg',
               "k" : b64'+a+Dg2jjU+eIiOFCa9lObw'
             }
           }
         }

         Figure 1: Example AS response with OSCOAP parameters.

   Figure 2 shows an example CWT, containing the necessary OSCOAP
   parameters in the 'cnf' claim, in CBOR diagnostic notation without
   tag and value abbreviations.

       {
         "aud" : "tempSensorInLivingRoom",
         "iat" : "1360189224",
         "exp" : "1360289224",
         "scope" :  "temperature_g firmware_p",
         "cnf" : {
           "COSE_Key" : {
             "kty" : "Symmetric",
 

Seitz, L.               Expires January 1, 2018                 [Page 6]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

             "alg" : "AES-CCM-16-64-128",
             "sid" : b64'Qg',
             "rid" : b64'qA',
             "k" : b64'+a+Dg2jjU+eIiOFCa9lObw' 
         }
       }

          Figure 2: Example CWT with OSCOAP parameters.

2.2.1 Using the pop-key with EDHOC (EDHOC+OSCOAP)

   If EDHOC is used together with OSCOAP, and the pop-key (symmetric or
   asymmetric) is used to authenticate the messages in EDHOC, then the
   AS MUST provision the following data, in response to the access token
   request:

      o  a symmetric or asymmetric key (associated to the RS) (pop-key)
      o  if the pop-key is symmetric, a key identifier;

   How these parameters are communicated depends on the type of key
   (asymmetric or symmetric).

   In case of an asymmetric key, C MUST communicate its own asymmetric
   key to the AS in the 'cnf' parameter of the access token request, as
   specified in section 5.5.1 of [I-D.ietf-ace-oauth-authz].  Note that
   the key, sent by the AS in response to the access token request, is
   associated to the RS.

   Figure 3 shows an example of such a request in CBOR diagnostic
   notation without tag and value abbreviations.

      Header: POST (Code=0.02)
      Uri-Host: "server.example.com"
      Uri-Path: "token"
      Content-Type: "application/cose+cbor"
      Payload:
      {
        "grant_type" : "client_credentials",
        "cnf" : {
          "COSE_Key" : {
            "kty" : "EC",
            "crv" : "P-256",
            "x" : b64'usWxHK2PmfnHKwXPS54m0kTcGJ90UiglWiGahtagnv8',
            "y" : b64'IBOL+C3BttVivg+lSreASjpkttcsz+1rb7btKLv8EX4'
          }
        }
      }

 

Seitz, L.               Expires January 1, 2018                 [Page 7]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

     Figure 3: Example access token request with asymmetric pop key.

   In the case of a symmetric key, the AS MUST communicate the key to
   the client in the 'cnf' parameter of the access token response, as
   specified in section 5.5.2. of [I-D.ietf-ace-oauth-authz].   AS MUST
   also select a key identifier, that MUST be included as the 'kid'
   parameter either directly in the 'cnf' structure, as in figure 4 of
   [I-D.ietf-ace-oauth-authz], or as the 'kid' parameter of the
   COSE_key, as in figure 6 of [I-D.ietf-ace-oauth-authz].

   Figure 4 shows an example of the necessary parameters in the AS
   response to the access token request when EDHOC is used.  The example
   uses CBOR  diagnostic notation without tag and value abbreviations.

       Header: Created (Code=2.01)
         Content-Type: "application/cose+cbor"
         Payload:
         {
           "access_token" : b64'SlAV32hkKG ...
            (remainder of access token omitted for brevity)',
           "profile" : "coap_oscoap",
           "expires_in" : "3600",
           "cnf" : {
             "COSE_Key" : {
               "kty" : "Symmetric",
               "kid" : b64'5tOS+h42dkw',
               "k" : b64'+a+Dg2jjU+eIiOFCa9lObw'
             }
           }
         }

      Figure 4: Example AS response with EDHOC+OSCOAP parameters.

   In both cases, the AS MUST also include the same key identifier as
   'kid' parameter in the access token metadata. If the access token is
   a CWT [I-D.ietf-ace-cbor-web-token], the key identifier MUST be
   placed inside the 'cnf' claim as 'kid' parameter of the COSE_Key or
   directly in the 'cnf' structure (if the key is only referenced).

   Figure 5 shows an example CWT containing the necessary EDHOC+OSCOAP
   parameters in the 'cnf' claim, in CBOR diagnostic notation without
   tag and value abbreviations.

       {
         "aud" : "tempSensorInLivingRoom",
         "iat" : "1360189224",
         "exp" : "1360289224",
 

Seitz, L.               Expires January 1, 2018                 [Page 8]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

         "scope" :  "temperature_g firmware_p",
         "cnf" : {
           "COSE_Key" : {
             "kty" : "Symmetric",
             "kid" : b64'5tOS+h42dkw',
             "k" : b64'+a+Dg2jjU+eIiOFCa9lObw' 
         }
       }

         Figure 5: Example CWT with EDHOC+OSCOAP parameters.

   All other parameters defining OSCOAP security context are derived
   from EDHOC message exchange, including the master secret (see
   Appendix C.2 of [I-D.selander-ace-cose-ecdhe]).

   To provide forward secrecy and mutual authentication in the case of
   pre-shared keys, pre-established raw public keys or with X.509
   certificates it is RECOMMENDED to use EDHOC [I-D.selander-ace-cose-
   ecdhe] to generate the keying material.  EDHOC MUST be used as
   defined in Appendix C, with the following additions and
   modifications.

   The first CoAP message is sent to the RS using the /authz-info
   endpoint as specified in section 5.7.1 of the ACE framework. This
   message MUST carry message_1 of the EDHOC protocol (section 4.2. if
   asymmetric keys are used or 5.2. if symmetric keys are used of [I-
   D.selander-ace-cose-ecdhe]) in the CoAP payload, and the access token
   MUST be added to the message_1 APP_1 as an element in a serialized
   CBOR map, with the label 'access_token' (Figure 11 of [I-D.ietf-ace-
   oauth-authz]).  An example can be seen in the first message (POST) of
   Figure 1.

   Before the RS continues with the EDHOC protocol and responds to this
   token submission request, additional verifications on the access
   token are done: the RS SHALL process the access token according to
   [I-D.ietf-ace-oauth-authz].  If the token is valid then the RS
   continues processing EDHOC following Appendix C of [I-D.selander-ace-
   cose-ecdhe], else it discontinues EDHOC and responds with the error
   code as specified in [I-D.ietf-ace-oauth-authz].

   When the RS receives an OSCOAP message including a field with label
   'edhoc_m3' in the unprotected Headers of the COSE object, it SHALL
   follow the process described in Appendix C of [I-D.selander-ace-cose-
   ecdhe].  If the OSCOAP message was valid, the RS SHALL also verify
   that the client is authorized to perform the requested action on the
   requested resource using the previously received access token. 

      o  In case the EDHOC verification fails, the RS MUST return an
 

Seitz, L.               Expires January 1, 2018                 [Page 9]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

   error response to the client with code 4.01 (Unauthorized).

      o  If RS has an access token for C but not for the resource that C
   has requested, RS MUST reject the request with a 4.03 (Forbidden).

      o  If RS has an access token for C but it does not cover the
   action C requested on the resource, RS MUST reject the request with a
   4.05 (Method Not Allowed).

   If all verifications above succeeds, further communication between
   client and RS is protected with OSCOAP, including the RS response to
   the OSCOAP request.

   In the case of EDHOC being used with symmetric pop-keys, the protocol
   in section 5 of [I-D.selander-ace-cose-ecdhe] MUST be used.  If the
   pop-key is asymmetric, the RS MUST also use an asymmetric key for
   authentication.  This key is known to the client through the access
   token response (see section 5.5.2 of the ACE framework).  In this
   case the protocol in section 4 of [I-D.selander-ace-cose-ecdhe] MUST
   be used.

   Note that if the OSCOAP profile is used, the /authz-info endpoint at
   the Resource Server MUST be prepared to process and generate the
   protocol messages of the EDHOC protocol as specified above.  Hence
   the use of EDHOC does not add any additional roundtrips to the ACE
   message exchange.

     Figure 6 illustrates the message exchanges for using EDHOC on the
   /authz-info endpoint (step C in figure 1 of [I-D.ietf-ace-oauth-
   authz]).

                        Resource
               Client    Server
               |          |
               |          |
               +--------->| Header: POST (Code=0.02)
               | POST     | Uri-Path:"authz-info"
               |          | Content-Type: application/cbor
               |          | Payload: EDHOC message_1 + access token
               |          |
               |<---------+ Header: 2.04 Changed
               |          | Content-Type: application/cose+cbor
               | 2.05     | Payload: EDHOC message_2
               |          |   
               |          |
               +--------->| CoAP request +
               |  OSCOAP  | Object-Security option
 

Seitz, L.               Expires January 1, 2018                [Page 10]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

               | request  | COSE_Encrypt0:
               |          |  unprotected Header: EDHOC message_3
               |          |
               |<---------+ CoAP response +
               |  OSCOAP  | Object-Security option
               | response | 
               |          |  

      Figure 6: Key establishment with EDHOC via the authz-info endpoint

   Figure 7 shows an example of message_1 with an access token embedded
   in the unprotected header.

 

Seitz, L.               Expires January 1, 2018                [Page 11]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

        [
          1,                            # message type
          h'05c2dc'                     # session identifier
          h'5598a57b47db7f2c',          # random nonce
          h'a120a50102024478f679012001215
            82098f50a4ff6c05861c8860d13a6
            38ea56c3f5ad7590bbfbf054e1c7b
            4d91d628022f5',             # COSE_Key
          [1]                           # NIST P-256
          [ -27 ],                      # ECDH-SS + HKDF-256
          [ 12 ],                       # AES-CCM-64-64-128
          [ -7 ],                       # ES256
          [ -7 ],                       # ES256
          h'a16c6163636573735f746f6b656e # APP_3: access token
            ...
        ] 

   Figure 7: diagnostic notation of EDHOC message_1 with an access token

3. Client to Authorization Server

   As specified in the ACE framework section 5.5 [I-D.ietf-ace-oauth-
   authz], the Client and AS can also use CoAP instead of HTTP to
   communicate via the token endpoint.  This section specifies how to
   use OSCOAP between Client and AS together with CoAP.  The use of
   OSCOAP for this communication is OPTIONAL in this profile, other
   security protocols (such as DTLS) MAY be used instead.

   The client and the AS are expected to have pre-established
   credentials (e.g. raw public keys).  How these credentials are
   established is out of scope for this profile.  Furthermore the client
   and the AS communicate using CoAP through the token endpoint as
   specified in section 5.5 of [I-D.ietf-ace-oauth-authz].  At first
   point of contact, prior to making the token request and response, the
   client and the AS MAY perform an EDHOC exchange with the pre-
   established credentials to create forward secret keying material for
   use with OSCOAP.  Subsequent requests and the responses MUST be
   protected with OSCOAP.

4. Resource Server to Authorization Server

   As specified in the ACE framework section 5.6 [I-D.ietf-ace-oauth-
   authz], the RS and AS can also use CoAP instead of HTTP to
   communicate via the introspection endpoint.  This section specifies
   how to use OSCOAP between RS and AS together with CoAP.  The use of
   OSCOAP for this communication is OPTIONAL in this profile, other
   security protocols (such as DTLS) MAY be used instead.
 

Seitz, L.               Expires January 1, 2018                [Page 12]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

   The RS and the AS are expected to have pre-established credentials
   (e.g. symmetric keys).  How these credentials are established is out
   of scope for this profile.  Furthermore the RS and the AS communicate
   using CoAP through the introspection endpoint as specified in section
   5.6 of [I-D.ietf-ace-oauth-authz].  At first point of contact, prior
   to making the introspection request and response, the RS and the AS
   MAY perform an EDHOC exchange with the pre-established credentials to
   create forward secret keying material for use with OSCOAP. 
   Subsequent requests and the responses MUST be protected with OSCOAP.

5. Security Considerations

   TBD.

6. Privacy Considerations

   TBD.

7.  IANA Considerations 

   TBD. 'coap_oscoap' as profile id. Header parameters 'sid', 'rid',
   'kdf' and 'slt' for COSE_Key.

8.  Acknowledgments

   The author wishes to thank Goeran Selander and Marco Tiloca for the
   input on this memo.  The error responses specified in section 2.2.
   were originally specified by Gerdes et al. in 
   [I-D.ietf-ace-dtls-authorize].

9.  References

9.1  Normative References

   [I-D.ietf-core-object-security]
              Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
              "Object Security of CoAP (OSCOAP)", draft-ietf-core-
              object-security-03 (work in progress), May 2017.

   [I-D.selander-ace-cose-ecdhe]
              Selander, G., Mattsson, J., and F. Palombini, "Ephemeral
              Diffie-Hellman Over COSE (EDHOC)", draft-selander-ace-
              cose-ecdhe-06 (work in progress), April 2017.
 

Seitz, L.               Expires January 1, 2018                [Page 13]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

   [I-D.ietf-cose-msg]
              Schaad, J., "CBOR Object Signing and Encryption (COSE)",
              draft-ietf-cose-msg-24 (work in progress), November 2016.

   [I-D.ietf-ace-oauth-authz]
              Seitz, L., Selander, G., Wahlstroem, E., Erdtmann, S., and
              H. Tschofenig. "Authentication and Authorization for
              Constrained Environments (ACE)", draft-ietf-ace-oauth-
              authz-06 (work in progress), March 2017.

   [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-06 (work in progress), June 2017.

   [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>.

   [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>.

9.2  Informative References

   [I-D.ietf-ace-actors]
              Gerdes, S., Seitz, L., Selander, G., and C. Bormann (ed).
              "An Architecture for Authorization in Constrained
              Environments", draft-ietf-ace-actors-05 (work in
              progress), March 2017. 

   [I-D.ietf-ace-dtls-authorize]
              Gerdes, S., Bergmann, O., Bormann C., Selander, G., and
              L. Seitz, "Datagram Transport Layer Security (DTLS) 
              Profile for Authentication and Authorization for
              Constrained Environments (ACE)", draft-ietf-ace-dtls-
              authorize-00 (work in progress), June 2017.

   [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>.

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,
              <http://www.rfc-editor.org/info/rfc6749>.

   [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>.
 

Seitz, L.               Expires January 1, 2018                [Page 14]
INTERNET DRAFT           OSCOAP profile of ACE             June 30, 2017

   [RFC7231]  Fielding, R., Ed., and J. Reschke, Ed., "Hypertext
              Transfer Protocol (HTTP/1.1): Semantics and Content",
              RFC 7231, DOI 10.17487/RFC7231, June 2014,
              <http://www.rfc-editor.org/info/rfc7231>.

Author's Address

              Ludwig Seitz
              RISE SICS AB
              Scheelevagen 17
              22370 Lund
              SWEDEN
              EMail: ludwig.seitz@ri.se

              Martin Gunnarsson
              RISE SICS AB
              Scheelevagen 17
              22370 Lund
              SWEDEN
              EMail: martin.gunnarsson@ri.se

              Francesca Palombini
              Ericsson AB
              Farogatan 6
              SE-16480 Stockholm
              SWEDEN
              EMail: francesca.palombini@ericsson.com
 

Seitz, L.               Expires January 1, 2018                [Page 14]