Hi Dick,

I guess one thing that didn't quite come out in my first explanation is that 
the scopes could belong to different resource servers.  So I'd rather not hand 
RS1 an access token that can be used to access protected resources on RS2 or 
RS3.  That is too much power for any RS to have :)

Granted if I were using a holder of key profile of OAuth (something I am also 
very interested in) that could prevent such a thing from happening.  But even 
with that in place, it seems ugly to send a set of scopes to an RS that only 
supports a subset of those scopes (though I know it's done that way today).

I know a lot of my use cases are a bit atypical for the wg, but It still seems 
to me to be in line with the OAuth spirit to keep the access token as 
restricted as possible (both in terms of lifetime and in terms of scope).

adam


From: Dick Hardt [mailto:[email protected]]
Sent: Wednesday, October 31, 2012 12:19 PM
To: Lewis Adam-CAL022
Subject: Re: [OAUTH-WG] access tokens & refresh tokens of different scopes

If the latency is important, you can deal with the latency by making the first 
call to the RS with the original access token while you are waiting for the 
stricter scoped access token to come back. Once you have a stricter scope 
access token, you can replace the original access token.

In practice, I don't think the latency is going to be an issue, and myself, I 
would be making a call to get a new access token just before I was going to do 
some work since the access token is very short lived.

-- Dick

On Oct 31, 2012, at 10:00 AM, Lewis Adam-CAL022 
<[email protected]<mailto:[email protected]>> 
wrote:


I have a use case where I would like to request both an access token and a 
refresh token, but I would like the access token to have a scope less than that 
of the refresh token.  It is standard OAuth behavior for using the refresh 
token to request additional access tokens (of equal or lesser scope) but the 
first access token that comes back always has the "master scope" of the refresh 
token.

For various security concerns, I always want my access tokens to be of a 
stricter scope that the refresh token.  For example, consider the scenario of a 
structured (JWT) access token that does not require the RS to call back to the 
AS introspection endpoint.  Following typical OAuth guidance, it is best 
practice to use short lived access tokens with long lived refresh tokens.  But 
I'd rather a compromised access token not compromise access to ALL my resource 
servers.

Using the existing standard I could simply destroy the first access token when 
it is received and then request another of lesser scope using the refresh 
token, but now I've just wasted a round trip over the air, consuming bandwidth 
and adding latency to the end user experience.

Is there anybody in the working group that feels this would be valuable?


adam

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