Optimizations for Using TLS Early Data in HTTP/2
draft-thomson-httpbis-h2-0rtt-00

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Network Working Group                                         M. Thomson
Internet-Draft                                                   Mozilla
Updates: 7540, 8441 (if approved)                       16 December 2020
Intended status: Standards Track                                        
Expires: 19 June 2021

            Optimizations for Using TLS Early Data in HTTP/2
                    draft-thomson-httpbis-h2-0rtt-00

Abstract

   This proposes an extension to HTTP/2 that enables the use of server
   settings by clients that send requests in TLS early data.  In
   particular, this allows extensions to the protocol to be used.

   This amends the definition of settings defined in RFC 7540 and RFC
   8441 and introduces new registration requirements for HTTP/2
   settings.

Discussion Venues

   This note is to be removed before publishing as an RFC.

   Discussion of this document takes place on the HTTP Working Group
   mailing list (ietf-http-wg@w3.org), which is archived at
   https://lists.w3.org/Archives/Public/ietf-http-wg/.

   Source for this draft and an issue tracker can be found at
   https://github.com/martinthomson/h2-0rtt.

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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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 19 June 2021.

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Copyright Notice

   Copyright (c) 2020 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
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   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  EARLY_DATA_SETTINGS Setting . . . . . . . . . . . . . . . . .   3
     3.1.  Server Handling . . . . . . . . . . . . . . . . . . . . .   3
     3.2.  Client Handling . . . . . . . . . . . . . . . . . . . . .   4
     3.3.  Use for Resumption  . . . . . . . . . . . . . . . . . . .   4
   4.  Settings in Early Data  . . . . . . . . . . . . . . . . . . .   5
     4.1.  Existing HTTP/2 Settings  . . . . . . . . . . . . . . . .   5
     4.2.  CONNECT Protocol  . . . . . . . . . . . . . . . . . . . .   6
     4.3.  Replay Attack Risk  . . . . . . . . . . . . . . . . . . .   7
     4.4.  Advertising Less-Permissive Values  . . . . . . . . . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   HTTP/2 [HTTP2] does not include any special provisions for the use of
   TLS early data as it was published prior to the introduction the
   feature in TLS 1.3 [TLS].  As a result, when using HTTP/2 with TLS
   early data, clients are forced to assume defaults for the server
   configuration.

   Using the initial value of settings can adversely affect performance
   as it can take an additional round trip or two to receive the
   connection preface from the server.  This is especially noticeable
   for new features that are added using extensions.  Clients that wish
   to use extensions therefore have to deal with extended delays before
   they can confirm server support for the extension.

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   In contrast, HTTP/3 [HTTP3] was defined for use with QUIC [QUIC],
   which includes early data (or 0-RTT) as a core features.  The use in