Compact TLS 1.3
draft-rescorla-tls-ctls-02

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TLS Working Group                                            E. Rescorla
Internet-Draft                                                   Mozilla
Intended status: Informational                                 R. Barnes
Expires: January 9, 2020                                           Cisco
                                                           July 08, 2019

                            Compact TLS 1.3
                       draft-rescorla-tls-ctls-02

Abstract

   This document specifies a "compact" version of TLS 1.3.  It is
   isomorphic to TLS 1.3 but saves space by aggressive use of defaults
   and tighter encodings.  CTLS is not interoperable with TLS 1.3, but
   it should eventually be possible for the server to distinguish TLS
   1.3 and CTLS handshakes.

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
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   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 January 9, 2020.

Copyright Notice

   Copyright (c) 2019 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

Rescorla & Barnes        Expires January 9, 2020                [Page 1]
Internet-Draft                  CTLS 1.3                       July 2019

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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  Common Primitives . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Varints . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.2.  Record Layer  . . . . . . . . . . . . . . . . . . . . . .   4
     3.3.  Handshake Layer . . . . . . . . . . . . . . . . . . . . .   4
     3.4.  Extensions  . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Handshake Messages  . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  ClientHello . . . . . . . . . . . . . . . . . . . . . . .   5
       4.1.1.  KeyShare  . . . . . . . . . . . . . . . . . . . . . .   6
     4.2.  ServerHello . . . . . . . . . . . . . . . . . . . . . . .   7
       4.2.1.  KeyShare  . . . . . . . . . . . . . . . . . . . . . .   7
       4.2.2.  PreSharedKeys . . . . . . . . . . . . . . . . . . . .   8
     4.3.  EncryptedExtensions . . . . . . . . . . . . . . . . . . .   8
     4.4.  CertificateRequest  . . . . . . . . . . . . . . . . . . .   8
     4.5.  Certificate . . . . . . . . . . . . . . . . . . . . . . .   8
       4.5.1.  Key IDs . . . . . . . . . . . . . . . . . . . . . . .   9
       4.5.2.  CertificateVerify . . . . . . . . . . . . . . . . . .   9
       4.5.3.  Finished  . . . . . . . . . . . . . . . . . . . . . .   9
       4.5.4.  HelloRetryRequest . . . . . . . . . . . . . . . . . .  10
   5.  Handshake Size Calculations . . . . . . . . . . . . . . . . .  10
     5.1.  ECDHE w/ Signatures . . . . . . . . . . . . . . . . . . .  10
       5.1.1.  Flight 1 (ClientHello) ***  . . . . . . . . . . . . .  10
       5.1.2.  Flight 2 (ServerHello..Finished)  . . . . . . . . . .  10
       5.1.3.  Flight 3 (Client Certificate..Finished) . . . . . . .  11
   6.  cTLS as Compression Layer [[OPEN ISSUE]]  . . . . . . . . . .  12
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .  13
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   DISCLAIMER: This is a work-in-progress draft of cTLS and has not yet
   seen significant security analysis, so could contain major errors.
   It should not be used as a basis for building production systems.

   This document specifies a "compact" version of TLS 1.3 [RFC8446].  It
   is isomorphic to TLS 1.3 but designed to take up minimal bandwidth.