The Datagram Transport Layer Security (DTLS) Protocol Version 1.3
draft-ietf-tls-dtls13-38

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TLS                                                          E. Rescorla
Internet-Draft                                                RTFM, Inc.
Obsoletes: 6347 (if approved)                              H. Tschofenig
Intended status: Standards Track                             Arm Limited
Expires: 30 November 2020                                    N. Modadugu
                                                            Google, Inc.
                                                             29 May 2020

   The Datagram Transport Layer Security (DTLS) Protocol Version 1.3
                        draft-ietf-tls-dtls13-38

Abstract

   This document specifies Version 1.3 of the Datagram Transport Layer
   Security (DTLS) protocol.  DTLS 1.3 allows client/server applications
   to communicate over the Internet in a way that is designed to prevent
   eavesdropping, tampering, and message forgery.

   The DTLS 1.3 protocol is intentionally based on the Transport Layer
   Security (TLS) 1.3 protocol and provides equivalent security
   guarantees with the exception of order protection/non-replayability.
   Datagram semantics of the underlying transport are preserved by the
   DTLS protocol.

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 30 November 2020.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Rescorla, et al.        Expires 30 November 2020                [Page 1]
Internet-Draft                  DTLS 1.3                        May 2020

   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
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   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
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   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
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   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   4
   3.  DTLS Design Rationale and Overview  . . . . . . . . . . . . .   6
     3.1.  Packet Loss . . . . . . . . . . . . . . . . . . . . . . .   6
     3.2.  Reordering  . . . . . . . . . . . . . . . . . . . . . . .   7
     3.3.  Message Size  . . . . . . . . . . . . . . . . . . . . . .   7
     3.4.  Replay Detection  . . . . . . . . . . . . . . . . . . . .   8
   4.  The DTLS Record Layer . . . . . . . . . . . . . . . . . . . .   8
     4.1.  Determining the Header Format . . . . . . . . . . . . . .  12
     4.2.  Sequence Number and Epoch . . . . . . . . . . . . . . . .  12
       4.2.1.  Processing Guidelines . . . . . . . . . . . . . . . .  13
       4.2.2.  Reconstructing the Sequence Number and Epoch  . . . .  13
       4.2.3.  Sequence Number Encryption  . . . . . . . . . . . . .  14
     4.3.  Transport Layer Mapping . . . . . . . . . . . . . . . . .  15
     4.4.  PMTU Issues . . . . . . . . . . . . . . . . . . . . . . .  15
     4.5.  Record Payload Protection . . . . . . . . . . . . . . . .  17
       4.5.1.  Anti-Replay . . . . . . . . . . . . . . . . . . . . .  17
       4.5.2.  Handling Invalid Records  . . . . . . . . . . . . . .  18
       4.5.3.  AEAD Limits . . . . . . . . . . . . . . . . . . . . .  18
   5.  The DTLS Handshake Protocol . . . . . . . . . . . . . . . . .  20
     5.1.  Denial-of-Service Countermeasures . . . . . . . . . . . .  20