Internet DRAFT - draft-erdtman-oauth-rpcc
draft-erdtman-oauth-rpcc
Web Authorization Protocol L. Seitz
Internet-Draft RISE SICS
Intended status: Informational S. Erdtman
Expires: May 24, 2018 Spotify AB
M. Tiloca
RISE SICS AB
November 20, 2017
Raw-Public-Key and Pre-Shared-Key as OAuth client credentials
draft-erdtman-oauth-rpcc-00
Abstract
This document describes Transport Layer Security (TLS) authentication
using Raw-Public-Key and Pre-Shared-Key as new mechanisms for OAuth
client authentication. Although defined for TLS the mechanisms are
equally applicable for DTLS.
Status of This Memo
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This Internet-Draft will expire on May 24, 2018.
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Pre-Shared-Key for Client Authentication . . . . . . . . . . 2
3. Raw-Public-Key for Client Authentication . . . . . . . . . . 3
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5.1. Token Endpoint Authentication Method Registration . . . . 4
5.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 4
5.1.2. Registry Contents . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
This document describes Transport Layer Security (TLS) authentication
using Raw-Public-Key and Pre-Shared-Key as the mechanism for OAuth
client authentication. Examples of endpoint requiring client
authentication are token and introspection.
The OAuth 2.0 Authorization Framework [RFC6749] defines a shared
secret method of client authentication but also allows for the
definition and use of additional client authentication mechanisms
when interacting with the authorization server's token endpoint.
This document describes two additional mechanisms of client
authentication utilizing Raw-Public-Key [RFC7250] and Pre-Shared-Key
TLS [RFC4279], which provide better security characteristics than
shared secrets.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Pre-Shared-Key for Client Authentication
The following section defines, as an extension of OAuth 2.0,
Section 2.3 [RFC6749], using Pre-Shared-Key with TLS [RFC4279] to
authenticate the client. This method is registered as
'tls_client_psk' in "OAuth Token Endpoint Authentication Methods"
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registry. If this method is to be used, the client and the
Authorization Server MUST share a secret key, and they MUST agree on
an identifier for this key.
The (D)TLS handshake MUST be done according to [RFC4279], with the
client indicating support for one or more Pre-Shared-Key cipher
suites and authorization server selecting a Pre-Shared-Key cipher
suite. In order to enable authorization server to select the correct
pre-shared-key the client MUST send the key identifier in the psk-
identity field of the ClientKeyExchange message. How the
authorization server maps an identifier to a pre-shared-key, and to a
client identity is out of scope for this specification.
Note that the client identity MUST be 2^16 bytes or shorter, in order
to fit into the psk-identity field.
3. Raw-Public-Key for Client Authentication
The following section defines, as an extension of OAuth 2.0,
Section 2.3 [RFC6749], the use of Raw-Public-Key with (D)TLS
[RFC7250] to authenticate the client. This method is registered as
'tls_client_rpk' in "OAuth Token Endpoint Authentication Methods"
registry.
The (D)TLS handshake MUST be done according to [RFC7250], with the
client indicating support for Raw-Public-Key certificates and the
authorization server asking client send its Raw Public Key
certificate. Since the client cannot send an explicit client
identifier in the handshake, the authorization server MUST the derive
a client identifier from RPK that the client uses.
Note to implementers: Authorization servers can use the following
method to map a Raw Public Key to a client identifier: The client
identifier is generated from the Raw Public Key using the procedure
specified in section 3 of [RFC6920]. The digest is calculated on the
Raw Public Key only (not on the SubjectPublicKeyInfo used in the
handshake). An example is shown in Figure 1.
Raw Public Key (Base64 encoded):
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEEtboxNKPgxEKV9JTNzy
tUvAbxEfkCTVB9kOzheF5wRAoOz2NKP+ln+XLVAQSp1D6jfo09tppvN
poQA1nnBNH6A==";
Encoding:
ni:///sha-256;xzLa24yOBeCkos3VFzD2gd83Urohr9TsXqY9nhdDN0
Figure 1: Example encoding of a raw public key in the Named
Information URI Format
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4. Acknowledgements
This document is highly inspired by [I-D.ietf-oauth-mtls] written by
B. Campbell, J. Bradley, N. Sakimura and T. Lodderstedt.
5. IANA Considerations
5.1. Token Endpoint Authentication Method Registration
This specification requests registration of the following value in
the IANA "OAuth Token Endpoint Authentication Methods" registry
[IANA.OAuth.Parameters] established by [RFC7591].
5.1.1. Registry Contents
o Token Endpoint Authentication Method Name: "tls_client_rpk"
o Change Controller: IESG
o Specification Document(s): [[ this specification ]]
5.1.2. Registry Contents
o Token Endpoint Authentication Method Name: "tls_client_psk"
o Change Controller: IESG
o Specification Document(s): [[ this specification ]]
6. Security Considerations
TBD
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>.
[RFC4279] Eronen, P., Ed. and H. Tschofenig, Ed., "Pre-Shared Key
Ciphersuites for Transport Layer Security (TLS)",
RFC 4279, DOI 10.17487/RFC4279, December 2005,
<https://www.rfc-editor.org/info/rfc4279>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/info/rfc6749>.
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[RFC6920] Farrell, S., Kutscher, D., Dannewitz, C., Ohlman, B.,
Keranen, A., and P. Hallam-Baker, "Naming Things with
Hashes", RFC 6920, DOI 10.17487/RFC6920, April 2013,
<https://www.rfc-editor.org/info/rfc6920>.
[RFC7250] Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J.,
Weiler, S., and T. Kivinen, "Using Raw Public Keys in
Transport Layer Security (TLS) and Datagram Transport
Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250,
June 2014, <https://www.rfc-editor.org/info/rfc7250>.
[RFC7591] Richer, J., Ed., Jones, M., Bradley, J., Machulak, M., and
P. Hunt, "OAuth 2.0 Dynamic Client Registration Protocol",
RFC 7591, DOI 10.17487/RFC7591, July 2015,
<https://www.rfc-editor.org/info/rfc7591>.
7.2. Informative References
[I-D.ietf-oauth-mtls]
Campbell, B., Bradley, J., Sakimura, N., and T.
Lodderstedt, "Mutual TLS Profile for OAuth 2.0", draft-
ietf-oauth-mtls-05 (work in progress), November 2017.
[IANA.OAuth.Parameters]
IANA, "OAuth Parameters",
<http://www.iana.org/assignments/oauth-parameters>.
Authors' Addresses
Ludwig Seitz
RISE SICS
Scheelevaegen 17
Lund 223 70
SWEDEN
Email: ludwig.seitz@ri.se
Samuel Erdtman
Spotify AB
Birger Jarlsgatan 61, 4tr
Stockholm 113 56
Sweden
Email: erdtman@spotify.com
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Marco Tiloca
RISE SICS AB
Isafjordsgatan 22
Stockholm 164 29
Sweden
Email: marco.tiloca@ri.se
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