Using Early Data in HTTP
draft-ietf-httpbis-replay-00

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Last updated 2017-09-06
Replaces draft-thomson-http-replay
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httpbis Working Group                                         M. Thomson
Internet-Draft                                                   Mozilla
Intended status: Standards Track                           M. Nottingham
Expires: March 10, 2018                                             true
                                                              W. Tarreau
                                                    HAProxy Technologies
                                                      September 06, 2017

                        Using Early Data in HTTP
                      draft-ietf-httpbis-replay-00

Abstract

   This document explains the risks of using early data for HTTP and
   describes techniques for reducing them.  In particular, it defines a
   mechanism that enables clients to communicate with servers about
   early data, to assure correct operation.

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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   This Internet-Draft will expire on March 10, 2018.

Copyright Notice

   Copyright (c) 2017 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
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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of

Thomson, et al.          Expires March 10, 2018                 [Page 1]
Internet-Draft               HTTP Early Data              September 2017

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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions and Definitions . . . . . . . . . . . . . . .   3
   2.  Early Data in HTTP  . . . . . . . . . . . . . . . . . . . . .   3
   3.  Supporting Early Data in HTTP Servers . . . . . . . . . . . .   3
   4.  Using Early Data in HTTP Clients  . . . . . . . . . . . . . .   5
   5.  Extensions for Early Data in HTTP . . . . . . . . . . . . . .   6
     5.1.  The Early-Data Header Field . . . . . . . . . . . . . . .   6
     5.2.  The 4NN (Too Early) Status Code . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
     6.1.  Gateways and Early Data . . . . . . . . . . . . . . . . .   8
     6.2.  Consistent Handling of Early Data . . . . . . . . . . . .   8
     6.3.  Denial of Service . . . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   TLS 1.3 [TLS13] introduces the concept of early data (also known as
   zero round trip data or 0-RTT data).  Early data allows a client to
   send data to a server in the first round trip of a connection,
   without waiting for the TLS handshake to complete if the client has
   spoken to the same server recently.

   When used with HTTP [HTTP], early data allows clients to send
   requests immediately, avoiding the one or two round trip delay needed
   for the TLS handshake.  This is a significant performance
   enhancement; however, it has significant limitations.

   The primary risk of using early data is that an attacker might
   capture and replay the request(s) it contains.  TLS [TLS13] describes
   techniques that can be used to reduce the likelihood that an attacker
   can successfully replay a request, but these techniques can be
   difficult to deploy, and still leave some possibility of a successful
   attack.

   Note that this is different from automated or user-initiated retries;
   replays are initiated by an attacker without the awareness of the
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