The Session Initiation Protocol (SIP) OAuth
draft-yusef-sipcore-sip-oauth-00
The information below is for an old version of the document.
| Document | Type |
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|---|---|---|---|
| Authors | Rifaat Shekh-Yusef , Victor Pascual | ||
| Last updated | 2014-05-26 | ||
| RFC stream | (None) | ||
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draft-yusef-sipcore-sip-oauth-00
SIPCORE Working Group R. Shekh-Yusef, Ed.
INTERNET-DRAFT Avaya
Intended Status: Standards Track V. Pascual
Expires: November 27, 2014 Quobis
May 26, 2014
The Session Initiation Protocol (SIP) OAuth
draft-yusef-sipcore-sip-oauth-00
Abstract
The Session Initiation Protocol (SIP) uses a challenge-response
framework to authenticate the user, but it does not have an
authorization framework to control the user's access to various
services in the system.
This document defines an authorization framework for SIP that is
based on the OAuth 2.0 framework.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
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Copyright and License Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://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.
Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
2 OAuth 2.0 Roles . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Resource Owner . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Resource Server . . . . . . . . . . . . . . . . . . . . . . 4
2.3 Client . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.4 Authorization Server . . . . . . . . . . . . . . . . . . . 4
3 Authorization Code Grant type . . . . . . . . . . . . . . . . . 5
3.1 Operations Overview . . . . . . . . . . . . . . . . . . . . 5
3.2 Registration . . . . . . . . . . . . . . . . . . . . . . . 7
3.3 Authorization . . . . . . . . . . . . . . . . . . . . . . . 7
3.4 Acquiring Access Token . . . . . . . . . . . . . . . . . . 8
3.5 Token Refresh . . . . . . . . . . . . . . . . . . . . . . . 9
3.6 Authenticated Requests . . . . . . . . . . . . . . . . . . 9
4 Resource Owner Password Credentials Grant type . . . . . . . . 11
4.1 Operations Overview . . . . . . . . . . . . . . . . . . . . 11
4.2 Registration and Acquiring Tokens . . . . . . . . . . . . . 12
4.3 Discarding Credentials . . . . . . . . . . . . . . . . . . 13
4.4 Token Refresh . . . . . . . . . . . . . . . . . . . . . . . 13
4.5 Authenticated Requests . . . . . . . . . . . . . . . . . . 13
4.6 Examples . . . . . . . . . . . . . . . . . . . . . . . . . 14
5 Client Credentials Grant . . . . . . . . . . . . . . . . . . . 15
5.1 Registration . . . . . . . . . . . . . . . . . . . . . . . 15
5.2 Authorization . . . . . . . . . . . . . . . . . . . . . . . 16
6 Security Considerations . . . . . . . . . . . . . . . . . . . . 17
7 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 17
8 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 17
9 References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
9.1 Normative References . . . . . . . . . . . . . . . . . . . 17
9.2 Informative References . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
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1 Introduction
The SIP protocol [RFC3261] uses the framework used by the HTTP
protocol for authenticating users, which is a simple challenge-
response authentication mechanism that allows a server to challenge a
client request and allows a client to provide authentication
information in response to that challenge.
The SIP protocol does not have an authorization framework to allow
the system to control access to various services provided by the
system.
OAuth 2.0 [RFC6749] defines a token based authorization framework to
allow clients to access resources on behalf of their user. It also
defines four types of authorization grants, which the client uses to
request the access token.
This document defines a new authorization mechanism for SIP that is
based on the OAuth 2.0 protocol. The new mechanism allows the proxy
to avoid challenging every request from the client. The use of tokens
is a Single Sing-On enabler, which allows for the definition of fine
grained scopes that could be used by proxies and application servers
to authorize clients to perform certain actions of behalf of the user
but not others.
1.1 Terminology
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].
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2 OAuth 2.0 Roles
2.1 Resource Owner
An entity capable of granting access to a protected resource. When
the resource owner is a person, it is referred to as an end-user.
2.2 Resource Server
The server hosting the protected resources, capable of accepting and
responding to protected resource requests using access tokens.
The Proxy will play this role with SIP.
2.3 Client
An application making protected resource requests on behalf of the
resource owner and with its authorization. The term "client" does
not imply any particular implementation characteristics (e.g.,
whether the application executes on a server, a desktop, or other
devices).
2.4 Authorization Server
The server issuing access tokens to the client after successfully
authenticating the resource owner and obtaining authorization.
The Registrar will play this role with SIP when first-party
authentication is used.
[[OPEN ISSUE]]
The rest of the document assumes that the Authorization Server plays two
roles: the Authorization Endpoint role and the Token Endpoint role.
Do we need to consider separating them?
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3 Authorization Code Grant type
3.1 Operations Overview
The following figure provides a high level view of flow of messages
for the Authorization Code Grant type:
User Proxy Authorization
Agent Server
---------------------------------------------------------------------
| | |
| REGISTER username@domain.com | |
|------------------------------>| |
| 302 | |
|<------------------------------| |
| | |
| GET /authorize?response_type=code&... |
|-------------------------------------------------------------->|
| | 401 |
|<--------------------------------------------------------------|
| | |
| | |
o master-key = HMAC-SHA256(HA1, realm + nonce) |
| | |
| GET /authorize?response_type=code&... with credentials |
|-------------------------------------------------------------->|
| | |
| | |
| o master-key=HMAC-SHA256(HA1, realm + nonce)
| | |
| | 302 [code] |
|<--------------------------------------------------------------|
| | |
| | |
| REGISTER username@domain.com & code |
|------------------------------>| |
| | POST /token [code] |
| |------------------------------>|
| | 200 OK [ token, |
| | refresh token, |
| | master-key] |
| |<------------------------------|
| 200 OK | |
|<------------------------------| |
| | |
| | |
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Subsequent Requests
| | |
o pop = HMAC-SHA256(master-key, some-request-headers) |
| | |
| INVITE pop | |
|------------------------------>| |
| | |
| | |
| o The proxy verifies the pop. |
| | |
| 180 Ringing | |
|<------------------------------| |
| | |
Token Refresh
| | |
| | POST /token |
| | [ grant_type=refresh_token& |
| | refresh_token=<ref_token> |
| |------------------------------>|
| | 200 OK [ token, |
| | refresh_token ] |
| |<------------------------------|
| | |
During registration the UA initially sends a REGISTER request without
providing any credentials.
The registrar then redirect the UA by responding with 302 that
includes the address of the Authorization Server.
The UA will then contact the Authorization Server without providing
any credentials in the first request. The Authorization Server
challenges the request using the Digest scheme, and the client
retries the request and provide the user's credentials.
The Authorization Server verifies the request from the client; if the
verification is successful, the Authorization Server responds with
302 to redirect the UA back to the registrar and include a code in
the body of the 302.
The UA then retries the request and include the code in the body of
the request. The registrar then contacts the Authorization Server and
exchanges the code for a token.
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3.2 Registration
The UA initiates the process by sending a REGISTER request to the
proxy. The proxy will redirect the UA to the Authorization Server by
responding with 302 that include the address of the Authorization
Server in the form of an HTTP URI.
The UA will then follow the authorization steps defined in section
3.3. At the end of the authorization process the UA will have a code
that it will use to complete the registration process.
The UA will send a new REGISTER request and include the code in the
body of the request with the following parameters:
grant_type (REQUIRED)
Value MUST be set to "authorization_code".
code (REQUIRED)
The authorization code received from the authorization server.
The proxy will then use the code to get a token from the
Authorization Server as defined in section 3.4. If the proxy is able
to obtain the token, the proxy will respond with 200 OK to the UA to
complete the registration process.
3.3 Authorization
The UA constructs the initial request without providing any user
credentials, but with the following URI parameters in the query
component:
response_type (REQUIRED)
Value MUST be set to "code".
scope (OPTIONAL)
The scope of the access request as described by Section x.x.
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state (RECOMMENDED)
The value of this parameter is a nonce created by the client to
prevent replay attack. The nonce is a uniquely generated value for
each request.
The Authorization Server challenges the request by responding with
401 with Digest scheme.
The UA will generate a master-key that is based on an HMAC-Hash
algorithm, e.g. HMAC-SHA256, that takes an input the user's HA1 and
the concatenation of realm and nonce received in the challenge from
the server.
The UA will then send a new authorization request, but this time
include the credentials requested by the server. The UA will use the
same parameters values used in the initial authorization request with
the exception of the state parameter which will get a new nonce
value.
When the server receives the request with the credentials, the server
will verify the digest provided by the UA; if that is successful, the
server will respond with 302 and include a code in the body of the
response with the following parameters:
grant_type (REQUIRED)
Value MUST be set to "authorization_code".
code (REQUIRED)
The authorization code received from the authorization server.
The server then generates a master-key that is based on an HMAC-
Hash algorithm, e.g. HMAC-SHA256, that takes an input the user's
HA1, and the concatenation of realm and nonce sent in the
challenge to the client.
3.4 Acquiring Access Token
The proxy receives the REGISTER request that includes a body with
a code, as specified in section 3.3. The proxy will then contact
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the Authorization Server to exchange the code with a token.
The proxy sends a POST request to the Authorization Server and
include the following parameters in the body:
grant_type (REQUIRED)
Value MUST be set to "authorization_code".
code (REQUIRED)
The authorization code received from the authorization server.
If the request is valid and authorized, the authorization server
responds with a 200 OK to complete the registration process, with
toke, token refresh, and the master-key in the body.
[[OPEN ISSUE]]
Should the proxy forward the tokens to the UA and expect the UA agent to
provide the token with subsequent requests and take care of refreshing
the token?
3.5 Token Refresh
The proxy makes a refresh request to the token by sending a refresh
POST request that includes a body with the grant_type and the
refresh_token.
For example:
grant_type=refresh_token&refresh_token=<some-token>
3.6 Authenticated Requests
When the UA wants to send any request to the proxy, it MUST include
the Authorization header and use the MAC scheme to carry the proof-
of-possession of the master-key.
The pop is calculated using the master-key as follows:
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pop = HMAC-SHA256(master-key, some-request-headers)
The following is an example of an Authorization header with Bearer
scheme:
Authorization: Bearer pop=<some-proof>
See rfc4474, section 9, for the SIP headers to hash to create the
value for the proof.
[[OPEN ISSUE]]
The Bearer scheme is used to deliver tokens without providing any proof
of possession. We probably need to use different scheme later on.
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4 Resource Owner Password Credentials Grant type
4.1 Operations Overview
The following figure provides a high level view of flow of messages
for the Resource Owner Password Credentials Grant type:
UA Proxy
--------------------------------------------------------------------
| |
| REGISTER username@domain.com |
|------------------------------------------------------------->|
| |
| 401 WWW-Authenticate: Digest |
|<-------------------------------------------------------------|
| |
| |
o master-key = HMAC-SHA256(HA1, realm + nonce) |
| |
| REGISTER username@domain.com with Authorization |
|------------------------------------------------------------->|
| |
| |
| o master-key=HMAC-SHA256(HA1, realm + nonce)
| |
| 200 OK [token, expires, ...] |
|<-------------------------------------------------------------|
| |
| |
o pop = HMAC-SHA256(master-key, token + some-request-headers) |
| |
| INVITE token, pop |
|------------------------------------------------------------->|
| |
| o The server verifies the pop.
| |
| 180 Ringing |
|<-------------------------------------------------------------|
| |
During registration the UA initially sends a REGISTER request without
providing any credentials.
The registrar then challenges the UA by responding with 401 that
includes the Digest scheme in the www-authenticate header.
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The UA will generate a master-key that is based on an HMAC-Hash
algorithm, e.g. HMAC-SHA256, that takes an input the user's HA1 and
the concatenation of realm and nonce received in the challenge from
the server. The UA will continue to use the existing operation of
handling the Digest challenge and then sends a new REGISTER request
with the credentials to the server.
When the server receives the request with the credentials, the server
will verify the digest provided by the UA; if that is successful, the
server will accept the registration and include the details of the
token in the response.
The server then generates a master-key that is based on an HMAC-Hash
algorithm, e.g. HMAC-SHA256, that takes an input the user's HA1, and
the concatenation of realm and nonce sent in the challenge to the
client.
At the end of the above process the UA would have registered with the
proxy and both the UA and the registrar would have created the same
master-key without sending the master key on the wire.
Later when the UA wants to send a request to the proxy it MUST always
include the token and SHOULD use the master-key to hash the
concatenation of the token and the following headers from the SIP
request: See rfc4474, section 9.
The resulted hash will be included in the request as a proof-of-
possession of the master-key.
4.2 Registration and Acquiring Tokens
The UA MUST request the access token during the registration process
with the proxy, by including a body with the grant_type as
"password". Initially, the UA sends a REGISTER request without
providing any credentials.
The registrar MUST then challenge the UA by responding with 401 with
the Digest scheme in the WWW-Authenticate header.
When the UA gets challenged by the proxy to provide its credentials,
the UA MUST include its credentials in the new REGISTER request in
the authorization header as it is done with the existing mechanism,
and MUST include a body with the grant_type as "password".
In addition, the UA MUST generate a master-key as follows:
master-key = HMAC-SHA256(HA1, realm + nonce)
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o HA1 - this is the user's H(A1) as defined in [HTTP-DIGEST].
o realm - this is the realm that is returned by the server in the
response to the initial request from the UA.
o nonce - this is the nonce that is returned by the server in the
response to the initial request from the UA.
When the server receives the request with the credentials, the server
will verify the digest provided by the UA; if that is successful, the
server will accept the registration and include the details of the
token in the response.
The server then generates a master-key following the same procedure
followed by the client.
As a result of this procedure both the UA and the server would have
created the same master-key without sending the master key on the
wire.
4.3 Discarding Credentials
After successfully receiving the access and refresh tokens from the
registrar, the UA SHOULD discard the user credentials.
4.4 Token Refresh
The UA makes a refresh request to the token by sending a refresh
REGISTER request that includes the authorization header and a body
with the grant_type, the refresh_token, and the proof-of-possession
of the master-key.
For example:
grant_type=refresh_token&refresh_token=<some-token>&pop=<some-proof>
4.5 Authenticated Requests
When the UA wants to send any request to the proxy, it MUST include
the Authorization header and use the Bearer scheme to carry the
access token, and the proof-of-possession of the master-key. For
example:
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Authorization: Bearer token=<some-token>, pop=<some-proof>
See rfc4474, section 9, for the SIP headers to hash to create the
value for the proof.
[[OPEN ISSUE]]
The Bearer scheme is used to deliver tokens without providing any proof
of possession. We probably need to use different scheme later on.
4.6 Examples
REGISTER sip:registrar.biloxi.com SIP/2.0
Via: SIP/2.0/TCP bobspc.biloxi.com:5060;branch=z9hG4bKnashds7
Max-Forwards: 70
To: Bob <sip:bob@biloxi.com>
From: Bob <sip:bob@biloxi.com>;tag=456248
Call-ID: 843817637684230@998sdasdh09
CSeq: 1826 REGISTER
Contact: <sip:bob@192.0.2.4>
Expires: 7200
Content-Length: 19
grant_type=password&pop=<some-proof>
SIP/2.0 200 OK
Via: SIP/2.0/TCP bobspc.biloxi.com:5060;branch=z9hG4bKnashds7
;received=192.0.2.4
To: Bob <sip:bob@biloxi.com>;tag=2493k59kd
From: Bob <sip:bob@biloxi.com>;tag=456248
Call-ID: 843817637684230@998sdasdh09
CSeq: 1826 REGISTER
Contact: <sip:bob@192.0.2.4>
Expires: 7200
Content-Length: 0
{
"access_token":"2YotnFZFEjr1zCsicMWpAA",
"token_type":"example",
"expires_in":3600,
"refresh_token":"tGzv3JOkF0XG5Qx2TlKWIA",
"example_parameter":"example_value"
}
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5 Client Credentials Grant
The following flow assumes that the UA is able to get a token using
some out-of-band mechanism, and the UA wants to use the token to
register, subscribe, and get service.
The flow uses a combination of the following from RFC6749:
o Client Credentials Grant defined in section 4.4
o Extensions Grants defined in section 4.5.
User Proxy Authorization
Agent Server
---------------------------------------------------------------------
| | |
| REGISTER username@domain.com, token |
|------------------------------>| |
| | |
| | POST /authorize |
| | [ grant_type = <some-urn] |
| | token=<some-token> ] |
| |------------------------------>|
| | |
| | 200 OK |
| | [validity, services] |
| |------------------------------>|
| | |
| 200 OK | |
|<------------------------------| |
| | |
| | |
5.1 Registration
The UA is in possession of a token that was obtained through some
out-of-band mechanism.
The UA sends a REGISTER request and include the token in the
Authorization header using the Bearer scheme as defined in RFC6750.
If the proxy is able to verify the token, the proxy accepts the
registration request and responds with 200 OK.
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5.2 Authorization
When the proxy receives the REGISTER request with the token, the
proxy will try to first validate the token before responding to the
UA request.
The proxy sends a POST request and include the following parameters
in the body of the request:
grant_type (REQUIRED)
Some well defined URN.
username (REQUIRED)
The resource owner username.
access_token (REQUIRED)
The token received from the UA.
scope (OPTIONAL)
The scope of the token.
If the authorization server is able to validate and authorize the
request, it will respond with 200 OK with a body that contains the
following parameters:
access_token, token_type, expires, refresh_token, scope
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6 Security Considerations
<Security considerations text>
7 IANA Considerations
8 Acknowledgments
<Acknowledgments text>
9 References
9.1 Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand
Key Derivation Function (HKDF)", RFC 5869, May 2010.
[RFC6749] Hardt, D., "The OAuth 2.0 Authorization Framework", RFC
6749, October 2012.
[HTTP-DIGEST] Shekh-Yusef, R., Ahrens, D., and Bremer, S., "HTTP
Digest Access Authentication", Work in Progress, January
2014.
https://datatracker.ietf.org/doc/draft-ietf-httpauth-
digest/
9.2 Informative References
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Authors' Addresses
Rifaat Shekh-Yusef (Editor)
Avaya
250 Sydney Street
Belleville, Ontario
Canada
Phone: +1-613-967-5267
Email: rifaat.ietf@gmail.com
Victor Pascual
Quobis
Spain
Email: victor.pascual@quobis.com
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