Session Description Protocol (SDP) Offer/Answer Considerations for Datagram Transport Layer Security (DTLS) and Transport Layer Security (TLS)
RFC 8842

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Internet Engineering Task Force (IETF)                       C. Holmberg
Request for Comments: 8842                                      Ericsson
Updates: 5763, 7345                                           R. Shpount
Category: Standards Track                                    TurboBridge
ISSN: 2070-1721                                             January 2021

   Session Description Protocol (SDP) Offer/Answer Considerations for
 Datagram Transport Layer Security (DTLS) and Transport Layer Security
                                 (TLS)

Abstract

   This document defines the Session Description Protocol (SDP) offer/
   answer procedures for negotiating and establishing a Datagram
   Transport Layer Security (DTLS) association.  The document also
   defines the criteria for when a new DTLS association must be
   established.  The document updates RFCs 5763 and 7345 by replacing
   common SDP offer/answer procedures with a reference to this
   specification.

   This document defines a new SDP media-level attribute, "tls-id".

   This document also defines how the "tls-id" attribute can be used for
   negotiating and establishing a Transport Layer Security (TLS)
   connection, in conjunction with the procedures in RFCs 4145 and 8122.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8842.

Copyright Notice

   Copyright (c) 2021 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 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.  Conventions
   3.  Establishing a New DTLS Association
     3.1.  General
     3.2.  Change of Local Transport Parameters
     3.3.  Change of ICE ufrag Value
   4.  SDP "tls-id" Attribute
   5.  SDP Offer/Answer Procedures
     5.1.  General
     5.2.  Generating the Initial SDP Offer
     5.3.  Generating the Answer
     5.4.  Offerer Processing of the SDP Answer
     5.5.  Modifying the Session
   6.  ICE Considerations
   7.  TLS Considerations
   8.  SIP Considerations
   9.  RFC Updates
     9.1.  General
     9.2.  Update to RFC 5763
       9.2.1.  Update to Section 1
       9.2.2.  Update to Section 5
       9.2.3.  Update to Section 6.6
       9.2.4.  Update to Section 6.7.1
     9.3.  Update to RFC 7345
       9.3.1.  Update to Section 4
       9.3.2.  Update to Section 5.2.1
       9.3.3.  Update to Section 9.1
   10. Security Considerations
   11. IANA Considerations
   12. References
     12.1.  Normative References
     12.2.  Informative References
   Acknowledgements
   Authors' Addresses

1.  Introduction

   [RFC5763] defines Session Description Protocol (SDP) offer/answer
   procedures for Secure Real-time Transport Protocol using Datagram
   Transport Layer Security (DTLS-SRTP).  [RFC7345] defines SDP offer/
   answer procedures for UDP Transport Layer over Datagram Transport
   Layer Security (UDPTL-DTLS).  This specification defines general
   offer/answer procedures for DTLS, based on the procedures in
   [RFC5763].  Other specifications, defining specific DTLS usages, can
   then reference this specification, in order to ensure that the DTLS
   aspects are common among all usages.  Having common procedures is
   essential when multiple usages share the same DTLS association
   [RFC8843].  This document updates [RFC5763] and [RFC7345] by
   replacing common SDP offer/answer procedures with a reference to this
   specification.

      |  NOTE: Since the publication of [RFC5763], [RFC4474] has been
      |  obsoleted by [RFC8224].  The updating of the references (and
      |  the associated procedures) within [RFC5763] is outside the
      |  scope of this document.  However, implementers of [RFC5763]
      |  applications are encouraged to implement [RFC8224] instead of
      |  [RFC4474].

   As defined in [RFC5763], a new DTLS association MUST be established
   when transport parameters are changed.  Transport parameter change is
   not well defined when Interactive Connectivity Establishment (ICE)