Hi Zachary,
Here is a use case for signed messages. I've tried to keep this in the
format of the other OAuth use cases. Please contact me off-list if there
are editorial changes required. I've include the list to see if others
have feed back on this use case.
Thanks,
George
Use case: Signed Messages
Description:
Alice manages all her personal health records in her personal health
data store (www.myhealth.example.com). Alice's Primary Care Physician
(www.pcp.example.com) recommends that Alice see a sleep specialist
(www.sleepwell.example.com). Alice arrives at the sleep specialist's
office and authorizes it to access her basic health data from her PCP.
The application at www.pcp.example.com verifies that Alice has
authorized www.sleepwell.example.com to access her health data as well
as enforces that www.sleepwell.example.com is the only application that
can retrieve that data with that specific authorization.
Pre-conditions:
* Alice has a personal health data store that allows for discovery of
her participating health systems (e.g. psychiatrist, sleep specialist,
pcp, orthodontist, ophthalmologist, etc).
* The application at www.myhealth.example.com manages authorization of
access to Alice's participating health systems
* The application at www.myhealth.example.com can issues authorization
tokens understood by Alice's participating health systems
* The application at www.pcp.example.com stores Alice's basic health and
prescription records
* The application at www.sleepwell.com stores results of Alice's sleep tests
Post-conditions:
* A successful procedure results in just the information that Alice
authorized being transferred from the Primary Care Physician
(www.pcp.example.com) to the sleep specialist (www.sleepwell.example.com).
* The transfer of health data only occurs if the application at
www.pcp.example.com can verify that www.sleepwell.example.com is the
party requesting access and that the authorization token presented by
www.sleepwell.example.com is issued by the application at
www.myhealth.example.com with a restricted audience of
www.sleepwell.example.com
Requirements:
* The application at www.sleepwell.example.com accesses
www.myhealth.example.com to discover the location of the PCP system (XRD
discovery)
* The application at www.sleepwell.example.com requests Alice to
authorize access to the application at www.pcp.example.com for the
purpose of retrieving basic health data (e.g. date-of-birth, weight,
height, etc). The mechanism Alice uses to authorize this access is out
of scope for this use case.
* The application at www.myhealth.example.com issues a token bound to
www.sleepwell.example.com for access to the application at
www.pcp.example.com. Note that a signed token (JWT) can be used to prove
who issued the token.
* The application at www.sleepwell.example.com constructs a request
(includes the token issued by www.myhealth.example.com) to the
application at www.pcp.example.com
* The application at www.sleepwell.example.com signs the request before
sending it to www.pcp.example.com
* The application at www.pcp.example.com receives the request and
verifies the signature
* The application at www.pcp.example.com parses the message and finds
the authorization token
* The application at www.pcp.example.com verifies the signature of the
authorization token
* The application at www.pcp.example.com parses the authorization token
and verifies that this token was issued to the application at
www.sleepwell.com
* The application at www.pcp.example.com retrieves the requested data
and returns it to the application at www.sleepwell.example.com
On 9/28/10 12:27 PM, Zeltsan, Zachary (Zachary) wrote:
These use cases are not in the draft
https://datatracker.ietf.org/doc/draft-zeltsan-use-cases-oauth.
Could you write them up?
Thanks,
Zachary
------------------------------------------------------------------------
*From:* oauth-boun...@ietf.org [mailto:oauth-boun...@ietf.org] *On
Behalf Of *George Fletcher
*Sent:* Tuesday, September 28, 2010 11:39 AM
*To:* OAuth WG
*Subject:* Re: [OAUTH-WG] Signatures...what are we trying to solve?
I think of the signature issues as falling into two classes... I think
they map to your classification as well...
* *Signing tokens* is important for interoperability especially
looking forward to a time when tokens issued by multiple
Authorization Servers are accepted at a given host.
* *Signing messages* is important because it provides a mechanism
to ensure that the entity making the API call (and presenting an
access token) is really the entity that is allowed to make the
API call.
Signing messages applies to the re-delegation use cases. I've heard
the need for this class of use cases from both the hData (health data)
community as well as the user managed access (UMA) community.
Signing tokens covers both your second class of tokens as well as
another use case that Eran has mentioned as well. Namely, a protected
resource server honoring tokens from multiple Authorization Servers.
These are the two classes of use cases that I'd like to see solved.
Thanks,
George
On 9/28/10 12:58 AM, David Recordon wrote:
If you know me then you'll know that I'm generally one of the last
people to talk about Alice and Bob. That said, there are a lot of
technical proposals flying across the list with very little shared
understanding of the problem(s) we're trying to solve.
From what I've seen there are two distinct classes of signature use cases.
1) The first is where the HTTP request parameters must be part of the
signature. An example is any OAuth 1.0a style API where you want to
make sure that the HTTP POST your server just received isn't
masquerading itself as a GET.
2) The second is where the HTTP request is orthogonal. An example
is OpenSocial where the server is sending state information to the
client such as what user is currently logged in.
The main practical example I have of the first use case is what
Twitter wants to do with redelegation. In this case TweetDeck can't
given TwitPic it's own bearer token, but needs to sign the POST
request and pass that signature to TwitPic for it to include in the
final API request to Twitter.
In terms of signing protected resource requests, I haven't heard
anyone bring up specific and detailed needs for this recently.
JSON tokens pretty clearly make sense for the second class of
signature use cases and it's actually a bit hard to argue why they
would be a part of OAuth. Facebook shipped this a bit over a month ago
for canvas applications. We include a `signed_request` parameter which
is signature.base64url(JSON). Parsing it is 18 lines of PHP.
http://developers.facebook.com/docs/authentication/canvas
This second class of use case will also be required by OpenID Connect
where the server is signing identity information and sending it to the
client. I imagine that OpenSocial will also still have it and wish to
continue relying on public key algorithms.
So a few questions:
* Do we want to tackle both of these classes of signatures in OAuth?
* Why do you consider the second class part of OAuth versus something
completely separate that might happen to include an OAuth access token?
* Is the Twitter redelegation use case the right focus for the first
class?
* Is there an example of an OAuth 2.0 server that can't use bearer
tokens for protected resource requests and thus requires signatures?
Thanks,
--David
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