draft-davidben-http2-tls13-00

draft-davidben-http2-tls13-00
Network Working Group D. Benjamin
Internet-Draft Google LLC
Updates:
7540
(if approved) April 01, 2019
Intended status: Standards Track
Expires: October 3, 2019
Using TLS 1.3 with HTTP/2
draft-davidben-http2-tls13-00
Abstract

This document clarifies the use of TLS 1.3 post-handshake
authentication and key update with HTTP/2.

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
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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 October 3, 2019.

This document is subject to
BCP 78
and the IETF Trust's Legal
Provisions Relating to IETF Documents
) in effect on the date of
publication of this document. Please review these documents
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Internet-Draft Using TLS 1.3 with HTTP/2 April 2019
Table of Contents
. Introduction . . . . . . . . . . . . . . . . . . . . . . . .
. Requirements Language . . . . . . . . . . . . . . . . . . . .
. Post-Handshake Authentication in HTTP/2 . . . . . . . . . . .
. Key Updates in HTTP/2 . . . . . . . . . . . . . . . . . . . .
. Security Considerations . . . . . . . . . . . . . . . . . . .
. IANA Considerations . . . . . . . . . . . . . . . . . . . . .
. Normative References . . . . . . . . . . . . . . . . . . . .
Author's Address . . . . . . . . . . . . . . . . . . . . . . . .
. 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 this. 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
has a different name. This makes it ambiguous whether post-handshake
authentication is allowed in TLS 1.3.

This document clarifies that the prohibition applies to post-
handshake authentication but not to key updates.
. 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.
. Post-Handshake Authentication in HTTP/2
The prohibition on renegotiation in
section 9.2.1 of [RFC7540]
additionally applies to TLS 1.3 post-handshake authentication.
HTTP/2 servers MUST NOT send post-handshake TLS 1.3
CertificateRequest messages. HTTP/2 clients MUST treat TLS 1.3 post-
Benjamin Expires October 3, 2019 [Page 2]
Internet-Draft Using TLS 1.3 with HTTP/2 April 2019
handshake authentication as a connection error (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.
. Key Updates in HTTP/2
Section 9.2.1 of [RFC7540]
does not extend to TLS 1.3 KeyUpdate
messages. HTTP/2 implementations MUST support key updates when TLS
1.3 is negotiated.
. Security Considerations
This document clarifies how to use HTTP/2 with TLS 1.3 and resolves a
compatibility concern 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. Permitting key updates
allows key material to be refreshed in long-lived HTTP/2 connections.
. IANA Considerations
This document has no IANA actions.
. 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,
>.

RFC5246
] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2",
RFC 5246
DOI 10.17487/RFC5246, August 2008,
>.
Benjamin Expires October 3, 2019 [Page 3]
Internet-Draft Using TLS 1.3 with HTTP/2 April 2019
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,
>.

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, <
>.

RFC7540
] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)",
RFC 7540
DOI 10.17487/RFC7540, May 2015,
>.

RFC8174
] Leiba, B., "Ambiguity of Uppercase vs Lowercase in
RFC
2119
Key Words",
BCP 14
RFC 8174
, DOI 10.17487/RFC8174,
May 2017, <
>.

RFC8446
] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3",
RFC 8446
, DOI 10.17487/RFC8446, August 2018,
>.

Author's Address

David Benjamin
Google LLC

Email: davidben@google.com

Benjamin Expires October 3, 2019 [Page 4]
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