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Network Working Group D. Schinazi
Internet-Draft Google LLC
Intended status: Experimental July 08, 2019
Expires: January 9, 2020
HTTP Transport Authentication
draft-schinazi-httpbis-transport-auth-00
Abstract
The most common existing authentication mechanisms for HTTP are sent
with each HTTP request, and authenticate that request instead of the
underlying HTTP connection, or transport. While these mechanisms
work well for existing uses of HTTP, they are not suitable for
emerging applications that multiplex non-HTTP traffic inside an HTTP
connection. This document describes the HTTP Transport
Authentication Framework, a method of authenticating not only an HTTP
request, but also its underlying transport.
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 January 9, 2020.
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
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
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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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions and Definitions . . . . . . . . . . . . . . . 3
2. Computing the Authentication Proof . . . . . . . . . . . . . 3
3. Header Field Definition . . . . . . . . . . . . . . . . . . . 4
3.1. The u Directive . . . . . . . . . . . . . . . . . . . . . 4
3.2. The p Directive . . . . . . . . . . . . . . . . . . . . . 4
3.3. The a Directive . . . . . . . . . . . . . . . . . . . . . 4
4. Transport Authentication Schemes . . . . . . . . . . . . . . 4
4.1. Signature . . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. HMAC . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Proxy Considerations . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7.1. Transport-Authentication Header Field . . . . . . . . . . 6
7.2. Transport Authentication Schemes Registry . . . . . . . . 6
7.3. TLS Keying Material Exporter Labels . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8
8.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The most common existing authentication mechanisms for HTTP are sent
with each HTTP request, and authenticate that request instead of the
underlying HTTP connection, or transport. While these mechanisms
work well for existing uses of HTTP, they are not suitable for
emerging applications that multiplex non-HTTP traffic inside an HTTP
connection. This document describes the HTTP Transport
Authentication Framework, a method of authenticating not only an HTTP
request, but also its underlying transport.
Traditional HTTP semantics specify that HTTP is a stateless protocol
where each request can be understood in isolation [RFC7230].
However, the emergence of QUIC [I-D.ietf-quic-transport] as a new
transport protocol that can carry HTTP [I-D.ietf-quic-http] and the
existence of QUIC extensions such as the DATAGRAM frame
[I-D.pauly-quic-datagram] enable new uses of HTTP such as
[I-D.vvv-webtransport-http3] and [I-D.schinazi-masque] where some
traffic is exchanged that is disctinct from HTTP requests and
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responses. In order to authenticate this traffic, it is necessary to
authenticate the underlying transport (e.g., QUIC or TLS [RFC8446])
instead of authenticate each request individually. This mechanism
aims to supplement the HTTP Authentication Framework [RFC7235], not
replace it.
Note that there is currently no mechanism for origin servers to
request that user agents authenticate themselves using Transport
Authentication, this is left as future work.
1.1. Conventions and Definitions
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.
This document uses the Augmented BNF defined in [RFC5234] and updated
by [RFC7405] along with the "#rule" extension defined in Section 7 of
[RFC7230]. The rules below are defined in [RFC3061], [RFC5234],
[RFC7230], and [RFC7235]:
OWS = <OWS, see {{RFC7230}}, Section 3.2.3>
quoted-string = <quoted-string, see {{RFC7230}}, Section 3.2.6>
token = <token, see {{RFC7230}}, Section 3.2.6>
token68 = <token, see {{RFC7235}}, Section 2.1>
oid = <oid, see {{RFC3061}}, Section 2>
2. Computing the Authentication Proof
This document only defines Transport Authentication for uses of HTTP
with TLS. This includes any use of HTTP over TLS as typically used
for HTTP/2, or HTTP/3 where the transport protocol uses TLS as its
authentication and key exchange mechanism [I-D.ietf-quic-tls].
The user agent leverages a TLS keying material exporter [RFC5705] to
generate a nonce which can be signed using the user-id's key. The
keying material exporter uses a label that starts with the characters
"EXPORTER-HTTP-Transport-Authentication-" (see Section 4 for the
labels and contexts used by each scheme). The TLS keying material
exporter is used to generate a 32-byte key which is then used as a
nonce.
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3. Header Field Definition
The "Transport-Authentication" header allows a user agent to
authenticate its transport connection with an origin server.
Transport-Authentication = transp-auth-scheme *( OWS ";" OWS parameter )
transp-auth-scheme = token
parameter = token "=" ( token / quoted-string )
3.1. The u Directive
The OPTIONAL "u" (user-id) directive specifies the user-id that the
user agent wishes to authenticate. It is encoded using Base64
(Section 4 of [RFC4648]).
u = token68
3.2. The p Directive
The OPTIONAL "p" (proof) directive specifies the proof that the user
agent provides to attest to possessing the credential that matches
its user-id. It is encoded using Base64 (Section 4 of [RFC4648]).
p = token68
3.3. The a Directive
The OPTIONAL "a" (algorithm) directive specifies the algorithm used
to compute the proof transmitted in the "p" directive.
a = oid
4. Transport Authentication Schemes
The Transport Authentication Framework allows defining Transport
Authentication Schemes, which specify how to authenticate user-ids.
This documents defined the "Signature" and "HMAC" schemes.
4.1. Signature
The "Signature" Transport Authentication Scheme uses asymmetric
cyptography. User agents possess a user-id and a public/private key
pair, and origin servers maintain a mapping of authorized user-ids to
their associated public keys. When using this scheme, the "u", "p",
and "a" directives are REQUIRED. The TLS keying material export
label for this scheme is "EXPORTER-HTTP-Transport-Authentication-
Signature" and the associated context is empty. The nonce is then
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signed using the selected asymmetric signature algorithm and
transmitted as the proof directive.
For example, the user-id "john.doe" authenticating using Ed25519
[RFC8410] could produce the following header (lines are folded to
fit):
Transport-Authentication: Signature u="am9obi5kb2U=";a=1.3.101.112;
p="SW5zZXJ0IHNpZ25hdHVyZSBvZiBub25jZSBoZXJlIHdo
aWNoIHRha2VzIDUxMiBiaXRzIGZvciBFZDI1NTE5IQ=="
4.2. HMAC
The "HMAC" Transport Authentication Scheme uses symmetric
cyptography. User agents possess a user-id and a secret key, and
origin servers maintain a mapping of authorized user-ids to their
associated secret key. When using this scheme, the "u", "p", and "a"
directives are REQUIRED. The TLS keying material export label for
this scheme is "EXPORTER-HTTP-Transport-Authentication-HMAC" and the
associated context is empty. The nonce is then HMACed using the
selected HMAC algorithm and transmitted as the proof directive.
For example, the user-id "john.doe" authenticating using HMAC-SHA-512
[RFC6234] could produce the following header (lines are folded to
fit):
Transport-Authentication: HMAC u="am9obi5kb2U=";a=2.16.840.1.101.3.4.2.3;
p="SW5zZXJ0IEhNQUMgb2Ygbm9uY2UgaGVyZSB3aGljaCB0YWtl
cyA1MTIgYml0cyBmb3IgU0hBLTUxMiEhISEhIQ=="
5. Proxy Considerations
Since Transport Authentication authenticates the underlying transport
by leveraging TLS keying material exporters, it cannot be
transparently forwarded by proxies that terminate TLS. However it
can be sent over proxied connections when TLS is performed end-to-end
(e.g., when using HTTP CONNECT proxies).
6. Security Considerations
Transport Authentication allows a user-agent to authenticate to an
origin server while guaranteeing freshness and without the need for
the server to transmit a nonce to the user agent. This allows the
server to accept authenticated clients without revealing that it
supports or expects authentication for some resources. It also
allows authentication without the user agent leaking the presence of
authentication to observers due to clear-text TLS Client Hello
extensions.
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7. IANA Considerations
7.1. Transport-Authentication Header Field
This document, if approved, requests IANA to register the "Transport-
Authentication" header in the "Permanent Message Header Field Names"
registry maintained at https://www.iana.org/assignments/message-
headers/ [1].
+--------------------------+----------+--------------+---------------+
| Header Field Name | Protocol | Status | Reference |
+--------------------------+----------+--------------+---------------+
| Transport-Authentication | http | experimental | This document |
+--------------------------+----------+--------------+---------------+
7.2. Transport Authentication Schemes Registry
This document, if approved, requests IANA to create a new HTTP
Transport Authentication Schemes Registry with the following entries:
+---------------------------------+---------------+
| Transport Authentication Scheme | Reference |
+---------------------------------+---------------+
| Signature | This document |
+---------------------------------+---------------+
| HMAC | This document |
+---------------------------------+---------------+
7.3. TLS Keying Material Exporter Labels
This document, if approved, requests IANA to register the following
entries in the "TLS Exporter Labels" registry maintained at
https://www.iana.org/assignments/tls-parameters/tls-
parameters.xhtml#exporter-labels [2]
+--------------------------------------------------+
| Value |
+--------------------------------------------------+
| EXPORTER-HTTP-Transport-Authentication-Signature |
+--------------------------------------------------+
| EXPORTER-HTTP-Transport-Authentication-HMAC |
+--------------------------------------------------+
Both of these entries are listed with the following qualifiers:
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+---------+-------------+---------------+
| DTLS-OK | Recommended | Reference |
+---------+-------------+---------------+
| N | Y | This document |
+---------+-------------+---------------+
8. References
8.1. 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>.
[RFC3061] Mealling, M., "A URN Namespace of Object Identifiers",
RFC 3061, DOI 10.17487/RFC3061, February 2001,
<https://www.rfc-editor.org/info/rfc3061>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/info/rfc4648>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>.
[RFC5705] Rescorla, E., "Keying Material Exporters for Transport
Layer Security (TLS)", RFC 5705, DOI 10.17487/RFC5705,
March 2010, <https://www.rfc-editor.org/info/rfc5705>.
[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>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235,
DOI 10.17487/RFC7235, June 2014,
<https://www.rfc-editor.org/info/rfc7235>.
[RFC7405] Kyzivat, P., "Case-Sensitive String Support in ABNF",
RFC 7405, DOI 10.17487/RFC7405, December 2014,
<https://www.rfc-editor.org/info/rfc7405>.
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[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>.
[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>.
8.2. Informative References
[I-D.ietf-quic-http]
Bishop, M., "Hypertext Transfer Protocol Version 3
(HTTP/3)", draft-ietf-quic-http-20 (work in progress),
April 2019.
[I-D.ietf-quic-tls]
Thomson, M. and S. Turner, "Using TLS to Secure QUIC",
draft-ietf-quic-tls-20 (work in progress), April 2019.
[I-D.ietf-quic-transport]
Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed
and Secure Transport", draft-ietf-quic-transport-20 (work
in progress), April 2019.
[I-D.pauly-quic-datagram]
Pauly, T., Kinnear, E., and D. Schinazi, "An Unreliable
Datagram Extension to QUIC", draft-pauly-quic-datagram-03
(work in progress), July 2019.
[I-D.schinazi-masque]
Schinazi, D., "The MASQUE Protocol", draft-schinazi-
masque-00 (work in progress), February 2019.
[I-D.vvv-webtransport-http3]
Vasiliev, V., "WebTransport over HTTP/3", draft-vvv-
webtransport-http3-00 (work in progress), May 2019.
[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011,
<https://www.rfc-editor.org/info/rfc6234>.
[RFC7427] Kivinen, T. and J. Snyder, "Signature Authentication in
the Internet Key Exchange Version 2 (IKEv2)", RFC 7427,
DOI 10.17487/RFC7427, January 2015,
<https://www.rfc-editor.org/info/rfc7427>.
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[RFC8410] Josefsson, S. and J. Schaad, "Algorithm Identifiers for
Ed25519, Ed448, X25519, and X448 for Use in the Internet
X.509 Public Key Infrastructure", RFC 8410,
DOI 10.17487/RFC8410, August 2018,
<https://www.rfc-editor.org/info/rfc8410>.
8.3. URIs
[1] https://www.iana.org/assignments/message-headers/
[2] https://www.iana.org/assignments/tls-parameters/tls-
parameters.xhtml#exporter-labels
Acknowledgments
The authors would like to thank many members of the IETF community,
as this document is the fruit of many hallway conversations. Using
the OID for the signature and HMAC algorithms was inspired by
Signature Authentication in IKEv2 [RFC7427].
Author's Address
David Schinazi
Google LLC
1600 Amphitheatre Parkway
Mountain View, California 94043
United States of America
Email: dschinazi.ietf@gmail.com
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