Extension of the CoAP-DTLS Profile for ACE to TLS
draft-ietf-ace-extend-dtls-authorize-05

ACE Working Group                                            O. Bergmann
Internet-Draft                                                       TZI
Updates: 9202 (if approved)                            J. Preuß Mattsson
Intended status: Standards Track                             G. Selander
Expires: 14 July 2023                                           Ericsson
                                                         10 January 2023

           Extension of the CoAP-DTLS Profile for ACE to TLS
                draft-ietf-ace-extend-dtls-authorize-05

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.

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   This Internet-Draft will expire on 14 July 2023.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Connection Establishment  . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     6.2.  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.  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.  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).

   In case the ace_profile parameter indicates the use of the DTLS
   profile for ACE as defined in [RFC9202], the Client MAY try to
   connect to the Resource Server via TLS, or 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, 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].

4.  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.

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   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]

5.  Security Considerations

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

6.  References

6.1.  Normative References

   [RFC2119]  Bradner, S. and RFC Publisher, "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. and RFC Publisher, "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>.

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

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   [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>.

6.2.  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

   Olaf Bergmann
   Universität Bremen TZI
   Bremen, D-28359
   Germany

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   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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