Internet DRAFT - draft-ietf-httpbis-http2-tls13
draft-ietf-httpbis-http2-tls13
HTTP D. Benjamin
Internet-Draft Google LLC
Updates: 7540 (if approved) October 17, 2019
Intended status: Standards Track
Expires: April 19, 2020
Using TLS 1.3 with HTTP/2
draft-ietf-httpbis-http2-tls13-03
Abstract
This document updates RFC 7540 by forbidding TLS 1.3 post-handshake
authentication, as an analog to the existing TLS 1.2 renegotiation
restriction.
Note to Readers
_RFC EDITOR: please remove this section before publication_
Discussion of this draft 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/ [1].
Working Group information can be found at https://httpwg.org/ [2];
source code and issues list for this draft can be found at
https://github.com/httpwg/http-extensions/labels/http2-tls13 [3].
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 April 19, 2020.
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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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Post-Handshake Authentication in HTTP/2 . . . . . . . . . . . 3
4. Other Post-Handshake TLS Messages in HTTP/2 . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . 5
7.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
TLS 1.2 [RFC5246] and earlier support renegotiation, a mechanism for
changing parameters and keys partway through a connection. This was
sometimes used to implement reactive client authentication in
HTTP/1.1 [RFC7230], where the server decides whether to request a
client certificate based on the HTTP request.
HTTP/2 [RFC7540] multiplexes multiple HTTP requests over a single
connection, which is incompatible with the mechanism above. Clients
cannot correlate the certificate request with the HTTP request which
triggered it. Thus, Section 9.2.1 of [RFC7540] forbids
renegotiation.
TLS 1.3 [RFC8446] updates TLS 1.2 to remove renegotiation in favor of
separate post-handshake authentication and key update mechanisms.
The former shares the same problems with multiplexed protocols, but
the prohibition in [RFC7540] only applies to TLS 1.2 renegotiation.
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This document updates HTTP/2 to similarly forbid TLS 1.3 post-
handshake authentication.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Post-Handshake Authentication in HTTP/2
HTTP/2 servers MUST NOT send post-handshake TLS 1.3
CertificateRequest messages. HTTP/2 clients MUST treat such messages
as connection errors (see Section 5.4.1 of [RFC7540]) of type
PROTOCOL_ERROR.
[RFC7540] permitted renegotiation before the HTTP/2 connection
preface to provide confidentiality of the client certificate. TLS
1.3 encrypts the client certificate in the initial handshake, so this
is no longer necessary. HTTP/2 servers MUST NOT send post-handshake
TLS 1.3 CertificateRequest messages before the connection preface.
The above applies even if the client offered the
"post_handshake_auth" TLS extension. This extension is advertised
independently of the selected ALPN protocol [RFC7301], so it is not
sufficient to resolve the conflict with HTTP/2. HTTP/2 clients that
also offer other ALPN protocols, notably HTTP/1.1, in a TLS
ClientHello MAY include the "post_handshake_auth" extension to
support those other protocols. This does not indicate support in
HTTP/2.
4. Other Post-Handshake TLS Messages in HTTP/2
[RFC8446] defines two other messages that are exchanged after the
handshake is complete, KeyUpdate and NewSessionTicket.
KeyUpdate messages only affect TLS itself and do not require any
interaction with the application protocol. HTTP/2 implementations
MUST support key updates when TLS 1.3 is negotiated.
NewSessionTicket messages are also permitted. Though these interact
with HTTP when early data is enabled, these interactions are defined
in [RFC8470] and allowed for in the design of HTTP/2.
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Unless the use of a new type of TLS message depends on an interaction
with the application-layer protocol, that TLS message can be sent
after the handshake completes.
5. Security Considerations
This document resolves a compatibility concern between HTTP/2 and TLS
1.3 when supporting post-handshake authentication with HTTP/1.1.
This lowers the barrier for deploying TLS 1.3, a major security
improvement over TLS 1.2.
6. IANA Considerations
This document has no IANA actions.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, <https://www.rfc-editor.org/info/rfc7301>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
7.2. Informative References
[RFC8470] Thomson, M., Nottingham, M., and W. Tarreau, "Using Early
Data in HTTP", RFC 8470, DOI 10.17487/RFC8470, September
2018, <https://www.rfc-editor.org/info/rfc8470>.
7.3. URIs
[1] https://lists.w3.org/Archives/Public/ietf-http-wg/
[2] https://httpwg.org/
[3] https://github.com/httpwg/http-extensions/labels/http2-tls13
Author's Address
David Benjamin
Google LLC
Email: davidben@google.com
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