Using Early Data in HTTP
RFC 8470
Document | Type | RFC - Proposed Standard (September 2018; No errata) | |
---|---|---|---|
Authors | Martin Thomson , Mark Nottingham , Willy Tarreau | ||
Last updated | 2018-09-21 | ||
Replaces | draft-thomson-http-replay | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Patrick McManus | ||
Shepherd write-up | Show (last changed 2018-03-27) | ||
IESG | IESG state | RFC 8470 (Proposed Standard) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Alexey Melnikov | ||
Send notices to | Patrick McManus <mcmanus@ducksong.com> | ||
IANA | IANA review state | IANA OK - Actions Needed | |
IANA action state | RFC-Ed-Ack |
Internet Engineering Task Force (IETF) M. Thomson Request for Comments: 8470 Mozilla Category: Standards Track M. Nottingham ISSN: 2070-1721 Fastly W. Tarreau HAProxy Technologies September 2018 Using Early Data in HTTP Abstract Using TLS early data creates an exposure to the possibility of a replay attack. This document defines mechanisms that allow clients to communicate with servers about HTTP requests that are sent in early data. Techniques are described that use these mechanisms to mitigate the risk of replay. 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/rfc8470. Copyright Notice Copyright (c) 2018 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. Thomson, et al. Standards Track [Page 1] RFC 8470 HTTP Early Data September 2018 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 . . . . . . . . . . . . . . . 7 5.2. The 425 (Too Early) Status Code . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6.1. Gateways and Early Data . . . . . . . . . . . . . . . . . 8 6.2. Consistent Handling of Early Data . . . . . . . . . . . . 9 6.3. Denial of Service . . . . . . . . . . . . . . . . . . . . 9 6.4. Out-of-Order Delivery . . . . . . . . . . . . . . . . . . 9 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 8.1. Normative References . . . . . . . . . . . . . . . . . . 10 8.2. Informative References . . . . . . . . . . . . . . . . . 11 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 1. Introduction TLS 1.3 [TLS13] introduces the concept of early data (also known as zero round-trip time (0-RTT) data). If the client has spoken to the same server recently, 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. When used with HTTP [HTTP], early data allows clients to send requests immediately, thus avoiding the one or two round-trip delays 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 client. Thomson, et al. Standards Track [Page 2] RFC 8470 HTTP Early Data September 2018 To help mitigate the risk of replays in HTTP, this document gives anShow full document text