Internet DRAFT - draft-yusef-sipcore-sip-oauth
draft-yusef-sipcore-sip-oauth
SIPCore R. Shekh-Yusef, Ed.
Internet-Draft Avaya
Updates: 3261 (if approved) V. Pascual
Intended status: Standards Track Oracle
Expires: March 9, 2017 C. Holmberg
Ericsson
September 5, 2016
The Session Initiation Protocol (SIP) OAuth
draft-yusef-sipcore-sip-oauth-04
Abstract
This document defines an authorization framework for SIP that is
based on the OAuth 2.0 framework, and adds a simple identity layer on
top of that, based on the OpenID Connect Core 1.0, to enable Clients
to verify the identity of the End-User based on the authentication
performed by an Authorization Server, as well as to obtain basic
profile information about the End-User.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3.1. Enterprise SSO . . . . . . . . . . . . . . . . . . . 4
1.3.2. 3GPP . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3.3. Confidential SIP Hardphone . . . . . . . . . . . . . 5
1.3.4. Public SIP Hardphone . . . . . . . . . . . . . . . . 5
1.3.5. SIP SSO . . . . . . . . . . . . . . . . . . . . . . . 6
1.4. Roles . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.5. ID Token . . . . . . . . . . . . . . . . . . . . . . . . 7
1.6. Authentication Types . . . . . . . . . . . . . . . . . . 8
2. Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1. Single Sign-On . . . . . . . . . . . . . . . . . . . . . 8
2.2. Service Authorization . . . . . . . . . . . . . . . . . . 8
2.3. Third-Party Authentication . . . . . . . . . . . . . . . 9
3. Authorization Code Grant type . . . . . . . . . . . . . . . . 9
3.1. Operations Overview . . . . . . . . . . . . . . . . . . . 9
3.2. Authentication . . . . . . . . . . . . . . . . . . . . . 12
3.3. Registration . . . . . . . . . . . . . . . . . . . . . . 13
3.4. Subsequent Requests . . . . . . . . . . . . . . . . . . . 14
3.5. Token Refresh . . . . . . . . . . . . . . . . . . . . . . 14
3.6. Services . . . . . . . . . . . . . . . . . . . . . . . . 15
4. Implicit Grant Type . . . . . . . . . . . . . . . . . . . . . 16
4.1. OAuth Implicit Grant . . . . . . . . . . . . . . . . . . 16
4.1.1. Overview . . . . . . . . . . . . . . . . . . . . . . 16
4.1.2. Authentication . . . . . . . . . . . . . . . . . . . 17
4.1.3. Registration . . . . . . . . . . . . . . . . . . . . 18
4.1.4. Subsequent Requests . . . . . . . . . . . . . . . . . 19
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4.1.5. Services . . . . . . . . . . . . . . . . . . . . . . 19
4.2. OpenID Implicit Grant . . . . . . . . . . . . . . . . . . 20
5. Resource Owner Password Credentials Grant type . . . . . . . 21
5.1. Operations Overview . . . . . . . . . . . . . . . . . . . 21
5.2. Registration and Acquiring Tokens . . . . . . . . . . . . 22
5.3. Discarding Credentials . . . . . . . . . . . . . . . . . 23
5.4. Token Refresh . . . . . . . . . . . . . . . . . . . . . . 23
5.5. Authenticated Requests . . . . . . . . . . . . . . . . . 23
5.6. Examples . . . . . . . . . . . . . . . . . . . . . . . . 24
6. Outbound . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.1. Authorization Code Grant type . . . . . . . . . . . . . . 25
6.2. Resource Owner Password Credentials Grant type . . . . . 25
7. Security Considerations . . . . . . . . . . . . . . . . . . . 25
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25
10. Normative References . . . . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
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.
The OpenID Connect 1.0 [OPENID] specifications defines a simple
identity layer on top of the OAuth 2.0 protocol, which enables
Clients to verify the identity of the End-User based on the
authentication performed by an Authorization Server, as well as to
obtain basic profile information about the End-User.
This document defines an authorization framework for SIP that is
based on the OAuth 2.0 framework, and adds the identity layer on top
of that, based on the OpenID Connect Core 1.0 specification
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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 [RFC2119].
1.2. Definitions
Types of SIP services:
* Basic SIP Services: make/receive call, transfer, call forward,
etc.
* Advanced SIP Services: services provided by SIP application
servers, e.g. Voice Mail, Conference Services, Presence, IM,
...
Single Sign-On (SSO)
SSO is a property that allows the user to be authenticated once
and as a result have access to multiple services in the system.
Authentication
The process of verifying the identity of a user trying to get
access to some network services.
Authorization
The process of controlling an authenticated user access to
network services and the level of service provided to the user.
1.3. Use Cases
1.3.1. Enterprise SSO
An enterprise is interested in providing its users with an SSO
capability to the various corporate services. The enterprise has an
authorization server for controlling the user access to their network
and would like to extend that existing authorization server to
control the user access to the various services provided by their SIP
network.
The user is expected to provide his corporate credentials to login to
the corporate network and get different types of services, regardless
of the protocol used to provide the service, and without the need to
create different accounts for these different types of services.
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1.3.2. 3GPP
The 3GPP network has a requirement to allow a user using a WebRTC IMS
Client (WIC) to authenticate to a WebRTC Authorization Function (WAF)
and in response be given an access token that allows the user to
register and get service from the 3GPP SIP network.
The WIC downloads an IMS webpage from the WebRTC Web Server Function
(WWSF) using HTTP. The WIC then requests an access token from the
WAF using HTTP, which the WIC then uses to register to the SIP
network throught the P-CSCF enhanced for WebRTC (eP-CSCF) element.
1.3.3. Confidential SIP Hardphone
A SIP hardphone with rich UI, that has the capability to maintain the
confidentiality of user's crecentials, is used to authenticate to an
authorization server, get a token, and use that token to register and
get service from the SIP network.
When the phone interacts with the authorization server and gets
challenged to provide credentials, the phone will prompt the user to
enter his credentials which will be used to authenticate to the
authorization server.
1.3.4. Public SIP Hardphone
A SIP hardphone with limited UI capabilities, that is incapable of
maintaining confidentiality of user's crecentials, is used to
register with the SIP network by providing an access code obtaied
from an authorization server.
When the phone interacts with the SIP network without providing any
credentials, the phone gets challenged to provide proper credentials.
The user will then use an out of band method, e.g browser, to
authenticate to the authorization server and get a short-lived
numeric access code.
The user will then use the phone's keypad to provide the numeric
access code to the SIP phone. The phone will then use the access
code to register and get service from the SIP network. The SIP Proxy
will exchange the access code with access token from the
authorization server.
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1.3.5. SIP SSO
An enterprise is interested in providing its users with an SSO
capability to the various corporate SIP services.
The enterprise wants to control the services provided to their SIP
users and the level of service provided to the user by their SIP
application servers without the need to create different accounts for
these services.
The enterprise wants to utilize an existing authentication mechanism
provided by SIP, but would like to be able to control who gets access
to what service and when.
The user is expected to use his SIP credentials to login to the SIP
network and get access to the basic services, and to get access to
the services provided by the various SIP application servers without
being challenged to provide credentials for each type of service.
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1.4. Roles
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.
In a typical SIP network, it is the management element in the
system that acts as a resource owner.
resource server
The server hosting the protected resources or services, capable
of accepting and responding to protected resource and services
requests using access tokens.
OAuth 2.0 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).
SIP client
An application making requests to access SIP services on behalf
of the end-user.
authorization server
The server issuing tokens to the OAuth 2.0 client or SIP Client
after successfully authenticating the resource owner and
obtaining authorization.
proof-of-possession (pop)
A hash used by one party to prove to another party that it is
in possession of some shared credentials, without sending the
credentials on the wire.
1.5. ID Token
ID token, as defined in the OpenID document, is a security token that
contains claims about the authentication of an end-user by an
authorization server.
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1.6. Authentication Types
There are two types of user authentications in SIP:
o Proxy-to-User: which allows a server that is providing a service
to authenticate the identity of a user before providing the
service.
o User-to-User: which allows a user recieving a request to
authenticate the identity of the remote user before processing the
request.
The mechanism defined in this document addresses the proxy-to-user
authentication only. For user-to-user authentication refer to the
mechanism defined in [STIR].
2. Benefits
This section describes the benefit of this authorization framework:
2.1. Single Sign-On
With the existing mechanism, the proxy and application servers might
need to challenge many of the requests sent by a client, which adds
traffic that could be avoided with this authorization mechanism.
Single Sign-On is a property that allows the user to be authenticated
once and as a result have access to multiple services in the system.
This authorization mechanism would enable Single Sign-On, as the user
will be authenticated once and as a result given a token and a
refresh token to allow the user access to various services based on
the token scope.
2.2. Service Authorization
This authorization mechanism allows the system to centrally control
the services provided to the user, e.g conference services, voice
mail, etc. The mechanism also allow control over the level of
services provided to the user; for example, if the user is given
access to conference services, the system controls whether the user
gets access to video conference services or only audio conference
services.
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2.3. Third-Party Authentication
This authorization mechanism allows the user to be authenticated and
obtain tokens using some Third-Party Authorization mechanism and
still get services from the system.
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:
Authentication
--------------
User Proxy Authorization
Agent Server
---------------------------------------------------------------------
| | |
| F1 REGISTER | |
|------------------------------>| |
| F2 401 | |
|<------------------------------| |
| | |
| F3 GET /authorize?response_type=code&... |
|-------------------------------------------------------------->|
| | F4 401 |
|<--------------------------------------------------------------|
| | |
| | |
o master-key = HMAC-SHA256(HA1, realm + nonce) |
| | |
| F5 GET /authorize?response_type=code&... with credentials |
|-------------------------------------------------------------->|
| | |
| | |
| o master-key=HMAC-SHA256(HA1, realm + nonce)
| | |
| | F6 200 [code] |
|<--------------------------------------------------------------|
| | |
| | |
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Registration
------------
User Proxy Authorization
Agent Server
---------------------------------------------------------------------
| | |
| F7 REGISTER code, pop | |
|------------------------------>| |
| | F8 POST /token [code] |
| |------------------------------>|
| | |
| | F9 200 OK [ id-token, |
| | access_token, |
| | refresh_token] |
| |<------------------------------|
| | |
| | |
| | F10 GET /userinfo [access_token]
| |------------------------------>|
| | |
| | F11 200 OK [ user-info, |
| | master-key] |
| |<------------------------------|
| | |
| F12 200 OK | |
|<------------------------------| |
| | |
| | |
Subsequent Requests
-------------------
| | |
o pop = HMAC-SHA256(master-key, digest-string) |
| | |
| F13 INVITE pop | |
|------------------------------>| |
| | |
| | |
| o The proxy verifies the pop. |
| | |
| F14 180 Ringing | |
|<------------------------------| |
| | |
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Token Refresh
-------------
User Proxy Authorization
Agent Server
---------------------------------------------------------------------
| | |
| | F15 POST /token |
| | [ grant_type=refresh_token& |
| | refresh_token=<ref_token> |
| |------------------------------>|
| | |
| | F16 200 OK [ access_token, |
| | refresh_token ] |
| |<------------------------------|
| | |
| | |
The UA initially sends a REGISTER request (F1) without providing any
credentials.
The proxy challenges the UA by responding with 401 (F2) that includes
the address of the Authorization Server.
[[OPEN ISSUE]] How should the UA be redirected to the Authorization
Server: 1. New SIP parameter? 2. Extend the Bearer scheme? 3.
Define a new Scheme?
The UA will then contact the Authorization Server without providing
any credentials in the first request (F3). The Authorization Server
challenges the request using the Digest scheme (F4), and the client
retries the request (F5) and provides the user's credentials.
The Authorization Server verifies the request from the client; if the
verification is successful, the Authorization Server responds with
200 OK (F6) and includes a code in the body part.
The UA then retries the request (F7) and include the code in the body
of the request. The proxy then contacts the Authorization Server and
exchanges the code for tokens (F8 and F9), and gets the user
information (F10 and F11). The proxy then sends 200 OK to the UA to
complete the registration process.
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3.2. Authentication
The UA initiates the process by sending a REGISTER request (F1) to
the proxy. The proxy will redirect the UA to the Authorization
Server by responding with 401 (F2) that includes the address of the
Authorization Server in the form of an HTTP URI.
The UA constructs the initial request (F3) to the Authorization
Server without providing any user credentials, but with the following
URI parameters in the query component:
response_type (REQUIRED)
Value MUST be set to "code".
user_id (REQUIRED)
The user's identification with the Authorization Server.
scope (OPTIONAL)
The scope of the access request
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. This parameter might not be included with the
initial request that does not include credentials (F3).
The Authorization Server uses the user identification specified in
the user_id parameter to verify that the user has an account in the
system, and then challenges the request by responding with 401 (F4)
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 (F5), 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 (F5), the
server will verify the digest provided by the UA; if that is
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successful, the server will respond with 200 OK (F6) 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 (F4) to
the client.
3.3. Registration
The UA will send a new REGISTER request (F7) 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 sends a POST request (F8) 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 (F9) with id_token, access token, and
refresh_token in the body.
The UA sends a GET request (F10) to the Authorization Server to fetch
the user information, and includes the access token in the body of
the request. In response the Autorization Server will respond with
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200 OK and include the user information and the master-key associated
with the user in the body part.
The proxy then responds with 200 OK (F12) to the UA to complete the
registration process.
3.4. Subsequent 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
proof-of-possession of the master-key.
The pop is calculated using the master-key as follows:
pop = HMAC-SHA256(master-key, digest-string)
The following is an example of an Authorization header with Bearer
scheme:
Authorization: Bearer pop=<pop>
See rfc4474, section 9, for the SIP headers to hash to create digest-
string.
[[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.
3.5. Token Refresh
The proxy makes a refresh request to the Authorization Server by
sending a refresh POST request (F13) that includes a body with the
grant_type and the refresh_token.
For example:
grant_type=refresh_token&refresh_token=<refresh_token>
If the proxy fails to refresh the token, then it MUST challenge the
next request from the UA, and as a result the UA MUST go through the
authorization process again to obtain new tokens.
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3.6. Services
When the UA tries to access a service on behalf of a user, e.g.
Voice Mail Service, the proxy forwards the request to the server
providing the service and MUST include an Authorization header with
the Bearer scheme that carries the token needed to get service, as
follows:
Authorization: Bearer token=<token>
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4. Implicit Grant Type
The impicit grant type is used by the SIP UA to directly obtain
access tokens from the Authorization Server to be able to register
and get service from the SIP network.
This grant type does not support the issuance of refresh tokens,
which means that the SIP UA must re-authenticate again to the
Authorization Server to get a new token before the current token
expires.
4.1. OAuth Implicit Grant
4.1.1. Overview
The following figure provides a high level view of flow of messages
for the OAuth Implicit Grant type:
Authentication
--------------
User Proxy Authorization
Agent Server
---------------------------------------------------------------------
| | |
| F1 GET /authorize?response_type=token... |
|-------------------------------------------------------------->|
| | |
| | F2 401 |
|<--------------------------------------------------------------|
| | |
| | |
| F3 GET /authorize?response_type=token +credentials |
|-------------------------------------------------------------->|
| | |
| | F4 200 OK [access_token] |
|<--------------------------------------------------------------|
| | |
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Registration
------------
| | |
| F5 REGISTER username@domain.com, access_token |
|------------------------------>| |
| | F6 POST /introspect |
| | [token=<access_token>] |
| |------------------------------>|
| | |
| | F7 200 OK |
| |<------------------------------|
| F8 200 OK | |
|<------------------------------| |
| | |
4.1.2. Authentication
The UA starts the process by sending an HTTP GET request to the
Authorization Server without providing any credentials in the first
request (F1).
The UA constructs the initial request (F1) to the Authorization
Server with the following URI parameters in the query component:
response_type (REQUIRED)
Value MUST be set to "token".
user_id (REQUIRED)
The user's identification with the Authorization Server.
scope (OPTIONAL)
The scope of the access request.
The Authorization Server challenges the request using the Digest
scheme (F2). The client retries the request (F3) and provides the
user's credentials. In response the Authorization Server responds
with 200 OK (F4) with the Access Token in the body.
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4.1.3. Registration
The UA starts the registration process with the SIP proxy by sending
a REGISTER request (F5) with the access token it obtained in the
previous steps (F1-F4).
The UA adds the following parameters to the body of the REGISTER
request:
access_token (REQUIRED)
The access token issued by the authorization server.
token_type (REQUIRED)
The type of the token issued by the authorization server. Value
is case insensitive.
expires (RECOMMENDED)
The lifetime in seconds of the access token.
scope (OPTIONAL)
The scope of the access request.
If introspection is used [RFC7662], then the proxy validates the
access token by sending an HTTP POST request (F6), with the
parameters sent as "application/x-www-form-urlencoded" data, to the
Authorization Server and include the following parameters:
token (REQUIRED)
The string value of the token.
token_type_hint (OPTIONAL)
A hint about the type of the token submitted for introspection.
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Authorization Server then validates the request and responds with 200
OK (F7), with a JSON object in the body with the following
parameters:
active (REQUIRED)
Boolean indicator of whether or not the presented token is
currently active.
scope (OPTIONAL)
The scope of the access request.
Other parameters
TBD.
4.1.4. Subsequent Requests
All subsequent requests from the UA MUST include a valid access
token. The UA MUST obtain a new access token before the access token
expiry period to continue to get service from the system.
4.1.5. Services
When the proxy forwards a request from a UA to an application server,
it makes sure to keep the access token and scope in the message to
allow the application server to provide the proper service to the
user.
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4.2. OpenID Implicit Grant
The following figure provides a high level view of flow of messages
for the OpenID Implicit Grant type:
User Proxy Authorization
Agent Server
---------------------------------------------------------------------
| | |
| F1 GET /authorize?response_type=id_token%20token... |
|-------------------------------------------------------------->|
| | |
| | F2 401 |
|<--------------------------------------------------------------|
| | |
| F3 GET /authorize?response_type=id_token%20token +credentials |
|-------------------------------------------------------------->|
| | |
| | F4 200 OK [ id-token, |
| | access_token] |
|<--------------------------------------------------------------|
| | |
| F5 GET /userinfo [access_token] |
|-------------------------------------------------------------->|
| | |
| | F6 200 OK [ user-info] |
|<--------------------------------------------------------------|
| | |
| F7 REGISTER username@domain.com, access_token |
|------------------------------>| |
| | |
| | F8 POST /authorize |
| | [token=access_token ] |
| |------------------------------>|
| | |
| | F9 200 OK |
| |<------------------------------|
| | |
| F10 200 OK | |
|<------------------------------| |
| | |
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5. Resource Owner Password Credentials Grant type
5.1. Operations Overview
The following figure provides a high level view of flow of messages
for the Resource Owner Password Credentials Grant type:
UA Proxy
--------------------------------------------------------------------
| |
| F1 REGISTER |
|------------------------------------------------------------->|
| |
| F2 401 WWW-Authenticate: Digest |
|<-------------------------------------------------------------|
| |
| |
o master-key = HMAC-SHA256(HA1, realm + nonce) |
| |
| F3 REGISTER with Authorization |
|------------------------------------------------------------->|
| |
| |
| o master-key = HMAC-SHA256(HA1, realm + nonce)
| |
| F4 200 OK [token, expires, ...] |
|<-------------------------------------------------------------|
| |
| |
o pop = HMAC-SHA256(master-key, token + digest-string) |
| |
| F5 INVITE token, pop |
|------------------------------------------------------------->|
| |
| o The server verifies the pop.
| |
| F6 180 Ringing |
|<-------------------------------------------------------------|
| |
During registration the UA initially sends a REGISTER request (F1)
without providing any credentials.
The proxy then challenges the UA by responding with 401 (F2) 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
(F3) with the credentials to the server.
When the server receives the request with the credentials (F3), the
server will verify the digest provided by the UA; if that is
successful, the server will accept the registration (F4) 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 proxy 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 include the pop as defined in section
4.6.
5.2. 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 proxy 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)
Where
o HA1 - this is the user's H(A1) as defined in [DIGEST].
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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.
[[OPEN ISSUE]] How should the tokens be transported to the UA? in the
body of the 200 OK? or a SIP header?
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.
5.3. Discarding Credentials
After successfully receiving the access and refresh tokens from the
proxy, the UA SHOULD discard the user credentials.
5.4. 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=<refresh_token>&pop=<pop>
5.5. 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:
Authorization: Bearer token=<token>, pop=<pop>
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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.
5.6. 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=<pop>
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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6. Outbound
RFC5626 defines a mechanism that allows a UA to simultaneously
connect and establish registration with multiple outbound proxies to
get service.
This section describes that impact of outbound on this authorization
mechanism.
6.1. Authorization Code Grant type
During initial registration with the primary proxy, the UA is able to
get an authorization code that it will use to register with the
primary proxy. Assuming the authorization server is shared between
the various outbound proxies, the UA will be able to use the same
authorization code to register with the secondary proxies and as a
result each one of the secondary proxies will get the master-key
associated with the user to be used for the calculation of the proof-
of-possession.
6.2. Resource Owner Password Credentials Grant type
During registration the proxy challenges the UA, and both the proxy
and the UA create a master-key based on HA1, realm, and nonce. Since
the nonce is not shared between the various proxies, it is not
possible for the outbound proxies to use the same master-key; as a
result, the UA is expected to maintain a master-key and token per
outbound proxy.
7. Security Considerations
<Security considerations text>
8. IANA Considerations
<IANA considerations text>
9. Acknowledgments
<Acknowledgments text>
10. Normative References
[OPENID] Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and
C. Mortimore, "OpenID Connect Core 1.0", February 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, H., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC6749] Hardt, D., "The OAuth 2.0 Authorization Framework",
RFC 6749, October 2012.
[RFC7662] Richer, J., "OAuth 2.0 Token Introspection", RFC 7662,
October 2015.
Authors' Addresses
Rifaat Shekh-Yusef (editor)
Avaya
250 Sidney Street
Belleville, Ontario
Canada
Phone: +1-613-967-5267
EMail: rifaat.ietf@gmail.com
Victor Pascual
Oracle
Spain
EMail: victor.pascual.avila@oracle.com
Christer Holmberg
Ericsson
Hirsalantie 11
Jorvas 02420
Finland
EMail: christer.holmberg@ericsson.com
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