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Extension of the CoAP-DTLS Profile for ACE to TLS
draft-ietf-ace-extend-dtls-authorize-06

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 9430.
Authors Olaf Bergmann , John Preuß Mattsson , Göran Selander
Last updated 2023-02-16 (Latest revision 2023-01-25)
Replaces draft-bergmann-ace-extend-dtls-authorize
RFC stream Internet Engineering Task Force (IETF)
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Reviews
Additional resources Mailing list discussion
Stream WG state Submitted to IESG for Publication
Document shepherd Daniel Migault
Shepherd write-up Show Last changed 2022-09-21
IESG IESG state Became RFC 9430 (Proposed Standard)
Consensus boilerplate Yes
Telechat date (None)
Responsible AD Roman Danyliw
Send notices to mglt.ietf@gmail.com
IANA IANA review state IANA OK - Actions Needed
draft-ietf-ace-extend-dtls-authorize-06
ACE Working Group                                            O. Bergmann
Internet-Draft                                                       TZI
Updates: 9202 (if approved)                            J. Preuß Mattsson
Intended status: Standards Track                             G. Selander
Expires: 29 July 2023                                           Ericsson
                                                         25 January 2023

           Extension of the CoAP-DTLS Profile for ACE to TLS
                draft-ietf-ace-extend-dtls-authorize-06

Abstract

   This document updates the CoAP-DTLS profile for ACE described in RFC
   9202 by specifying that the profile applies to TLS as well as DTLS.

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 29 July 2023.

Copyright Notice

   Copyright (c) 2023 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 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Specific Changes to RFC 9202  . . . . . . . . . . . . . . . .   3
   4.  Connection Establishment  . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   [RFC9202] only specifies the use of DTLS [RFC9147] but works equally
   well for TLS [RFC8446].  For many constrained implementations, CoAP
   over UDP [RFC7252] is the first choice, but when deploying ACE in
   networks controlled by other entities (such as the Internet), UDP
   might be blocked on the path between the client and the RS, and the
   client might have to fall back to CoAP over TCP [RFC8323] for NAT or
   firewall traversal.  This dual support for security over TCP as well
   as UDP is already supported by the OSCORE profile [RFC9203].

   This document updates [RFC9202] by specifying that the profile
   applies to TLS as well as DTLS.  It only impacts the transport layer
   security channel between Client and Resource Server.  The same access
   rights are valid in case transport layer security is provided by
   either DTLS or TLS.  The same access token can be used by either DTLS
   or TLS between a given (Client, RS) pair.  Therefore, the value
   coap_dtls in the ace_profile parameter of an AS-to-Client response or
   in the ace_profile claim of an access token indicates that either
   DTLS or TLS can be used for transport layer security.

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
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   Readers are expected to be familiar with the terms and concepts
   described in [RFC9200] and [RFC9202].

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3.  Specific Changes to RFC 9202

   The main changes to [RFC9202] specified in this document are limited
   to replacing "DTLS" with "DTLS/TLS" throughout the document.  This
   essentially impacts the use of secure transport as described in the
   sections 3.2.2, 3.3.2, 4, and 5.

   In addition to this, the Client and Resource Server behavior is
   updated to describe the case where either or both DTLS and TLS may be
   available, as described in the following section.

4.  Connection Establishment

   Following the procedures defined in [RFC9202], a Client can retrieve
   an Access Token from an Authorization Server (AS) in order to
   establish a security association with a specific Resource Server.
   The ace_profile parameter in the Client-to-AS request and AS-to-
   client response is used to determine the ACE profile that the Client
   uses towards the Resource Server (RS).

   The ace_profile parameter indicates the use of the DTLS profile for
   ACE as defined in [RFC9202].  Therefore, the Client typically first
   tries using DTLS to connect to the Resource Server.  If this fails
   the Client MAY try to connect to the Resource Server via TLS.  The
   client can try TLS and DTLS in parallel to accelerate the connection
   setup.  It is up to the implementation to handle the case where the
   RS reponds to both connection requests.

   As resource-constrained devices are not expected to support both
   transport layer security mechanisms.  Clients and Resource Servers
   SHOULD support DTLS and MAY support TLS.  A Client that implements
   either TLS or DTLS but not both might fail in establishing a secure
   communication channel with the Resource Server altogether.

   Note that a communication setup with an a priori unknown Resource
   Server typically employs an initial unauthorized resource request as
   illustrated in Section 2 of [RFC9202].  If this message exchange
   succeeds, the Client SHOULD first use the same underlying transport
   protocol also for the establishment of the security association to RS
   (i.e., DTLS for UDP, and TLS for TCP).

   As a consequence, the selection of the transport protocol used for
   the initial unauthorized resource request also depends on the
   transport layer security mechanism supported by the Client.  Clients
   that support either DTLS or TLS but not both SHOULD use the transport
   protocol underlying the supported transport layer security mechanism
   also for an initial unauthorized resource request to the RS as in
   Section 2 of [RFC9202].

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5.  IANA Considerations

   The following updates have been done to the "ACE Profiles" registry
   for the profile with a "CBOR Value" field value of 1 and "Name" of
   "coap_dtls":

   Note to RFC Editor: Please replace all occurrences of "[RFC-XXXX]"
   with the RFC number of this specification and delete this paragraph.

   Description: Profile for delegating client Authentication and
   Authorization for Constrained Environments by establishing a Datagram
   Transport Layer Security (DTLS) or Transport Layer Security (TLS)
   channel between resource-constrained nodes.

   Change Controller: IESG

   Reference: [RFC9202] [RFC-XXXX]

6.  Security Considerations

   The security consideration and requirements in [RFC9202], TLS 1.3
   [RFC8446], and BCP 195 [RFC8996] [RFC9325] also apply to this
   document.

7.  References

7.1.  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,
              <https://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,
              <https://www.rfc-editor.org/info/rfc7252>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8323]  Bormann, C., Lemay, S., Tschofenig, H., Hartke, K.,
              Silverajan, B., and B. Raymor, Ed., "CoAP (Constrained
              Application Protocol) over TCP, TLS, and WebSockets",
              RFC 8323, DOI 10.17487/RFC8323, February 2018,
              <https://www.rfc-editor.org/info/rfc8323>.

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   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [RFC9147]  Rescorla, E., Tschofenig, H., and N. Modadugu, "The
              Datagram Transport Layer Security (DTLS) Protocol Version
              1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022,
              <https://www.rfc-editor.org/info/rfc9147>.

   [RFC9200]  Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
              H. Tschofenig, "Authentication and Authorization for
              Constrained Environments Using the OAuth 2.0 Framework
              (ACE-OAuth)", RFC 9200, DOI 10.17487/RFC9200, August 2022,
              <https://www.rfc-editor.org/info/rfc9200>.

   [RFC9202]  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)", RFC 9202,
              DOI 10.17487/RFC9202, August 2022,
              <https://www.rfc-editor.org/info/rfc9202>.

7.2.  Informative References

   [RFC8996]  Moriarty, K. and S. Farrell, "Deprecating TLS 1.0 and TLS
              1.1", BCP 195, RFC 8996, DOI 10.17487/RFC8996, March 2021,
              <https://www.rfc-editor.org/info/rfc8996>.

   [RFC9203]  Palombini, F., Seitz, L., Selander, G., and M. Gunnarsson,
              "The Object Security for Constrained RESTful Environments
              (OSCORE) Profile of the Authentication and Authorization
              for Constrained Environments (ACE) Framework", RFC 9203,
              DOI 10.17487/RFC9203, August 2022,
              <https://www.rfc-editor.org/info/rfc9203>.

   [RFC9325]  Sheffer, Y., Saint-Andre, P., and T. Fossati,
              "Recommendations for Secure Use of Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
              2022, <https://www.rfc-editor.org/info/rfc9325>.

Acknowledgments

   The authors would like to thank Marco Tiloca for reviewing this
   specification.

Authors' Addresses

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   Olaf Bergmann
   Universität Bremen TZI
   Bremen, D-28359
   Germany
   Email: bergmann@tzi.org

   John Preuß Mattsson
   Ericsson AB
   SE-164 80 Stockholm
   Sweden
   Email: john.mattsson@ericsson.com

   Göran Selander
   Ericsson AB
   SE-164 80 Stockholm
   Sweden
   Email: goran.selander@ericsson.com

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