Re: [OAUTH-WG] Device Code expiration and syntax

[Mike Jones <[e-mail]>]

Thanks for doing this, William.  I added one comment to the pull request.  After addressing it, I support this new version being published.

                                                       -- Mike

From: William Denniss [mailto:[e-mail]]
Sent: Saturday, March 11, 2017 6:59 PM
To: Mike Jones <[e-mail]>
Cc: Justin Richer <[e-mail]>; <[e-mail]> <[e-mail]>
Subject: Re: [OAUTH-WG] Device Code expiration and syntax

Sure thing. Changes are staged here: https://github.com/WilliamDenniss/draft-ietf-oauth-device-flow/pull/3/files

Includes the normative change suggested by Justin. PTAL.

On Sat, Mar 11, 2017 at 1:46 PM, Mike Jones <[e-mail]<mailto:[e-mail]>> wrote:
The pre-Chicago submission deadline is Monday afternoon (see http://ietf.org/meeting/important-dates.html#ietf98).  Would you have time to check proposed edits into GitHub for the editors to review before that, William?

                                                       -- Mike

From: OAuth [mailto:[e-mail]<mailto:[e-mail]>] On Behalf Of William Denniss
Sent: Saturday, March 11, 2017 12:54 PM
To: Justin Richer <[e-mail]<mailto:[e-mail]>>
Cc: <[e-mail]<mailto:[e-mail]>> <[e-mail]<mailto:[e-mail]>>
Subject: Re: [OAUTH-WG] Device Code expiration and syntax


On Sat, Mar 11, 2017 at 12:40 PM, Justin Richer <[e-mail]<mailto:[e-mail]>> wrote:

On Mar 11, 2017, at 2:54 PM, William Denniss <[e-mail]<mailto:[e-mail]>> wrote:

On Sat, Mar 11, 2017 at 11:10 AM, Justin Richer <[e-mail]<mailto:[e-mail]>> wrote:
We’re implementing support for the device code draft and had a question on what the “expiration” of the code refers to. Obviously, once the code has expired it can no longer be used. But when should the expiration count from? Say I have a code that’s good for 60 seconds, do I start the timer as soon as I issue the code to the client? Do I reset the timer when the user approves the client, to another 60 seconds? Or does that 60 seconds count for the entire transaction?

My read on it is the latter-- one timeout for the entire lifetime of the code regardless of its current state, with no resets. But I didn’t find good guidance in the document itself.

It's the expiry of the user_code and device_code pair, at which point the device will need to start-over with a new device authorization request.  The device wouldn't *have* to start a timer, as they will get an error during polling:


   expired_token

      The "device_code" has expired.  The client will need to make a new

      Device Authorization Request.

We should add some guidelines around expiry behavior.

OK, so it really is one expiration for the whole thing. The device doesn’t need to care (and I’ll bet you right now that, just like with access tokens, the overwhelmingly vast majority of devices won’t care about expires_in), but the authorization server certainly does, and we wanted to know the right place to set the timers.


You're probably right that most ignore expires_in, and I think that's fine. As long as the client handles errors correctly, it'll work out OK.

Agree that we should add some documentation. One piece of advice for the AS would be not to make it too short, else users won't be able to complete the flow in time.

We use a 30 minute expiry.


Secondly, I had a question about the “response_type” parameter to the device endpoint. This parameter is required and it has a single, required value, with no registry or other possibility of extension. What’s the point? If it’s for “parallelism”, I’ll note that this is *not* the authorization endpoint (as the user is not present) and such constraints need not apply here.

Good points here. At a guess, it bled in from the OAuth spec. If it's not needed, we should remove it.


I’d vote for removal, I don’t see the point.

 — Justin