Re: [jose] DISCUSS: Nonce/Timestamp parameter

[Breno de Medeiros <[e-mail]>]

I agree that this should be looked independently of oauth2.

Nonce is a generally used concept in crypto, though sometimes protocol
designers have called for nonces with bad outcomes because the difficulty
of implementing nonce-checking was disregarded. However, difficulties to
implement nonces in general are not relevant if there is a compelling use
case that is able to leverage nonces effectively.

As for timestamps: we already have issued time and the nonce can embed a
timestamp additionally. So I don't think we need to concern ourselves with
timestamps when considering nonces.




On Tue, Aug 28, 2012 at 8:09 AM, John Bradley <[e-mail]> wrote:

> In OAuth 2 state gets overloaded with a bunch of things from preventing
> XSRF to providing a handle to look up who the the authorization request was
> sent to.
>
> In Connect we added a nonce sent by client that is returned inside the
> signed id_token (JWT) to allow the client to detect replay, and optionally
> reference a specific browser session that presents the id_token.
>
> The nonce I suggested for JOSE is not ether of those.
>
> I used nonce in the sense that it is used with stream cyphers when the
> same key is used over multiple messages.
>
> JOSE will be used for more than OAuth and JWT.   There are cases where
> adding entropy to the header will be a security benefit.  I would like to
> have a standard claim for doing that.
> If people want to call it something else that is fine, but it is a nonce
> by definition.
> If used it should be a random or pseudo random value that is time variant
> with sufficient granularity to ensure a nonce is used only once.
>
> John B.
>
> On 2012-08-28, at 10:32 AM, Justin Richer <[e-mail]> wrote:
>
>  On 08/25/2012 03:37 AM, Axel Nennker wrote:
>
> To clarify: What is the base specification that Jim mentioned?
> Is it: http://tools.ietf.org/html/draft-ietf-oauth-json-web-token-03 ?
>
> Would somebody please present a use-case for either nonce or timestamp?
> If a jwt is used with oauth2 then what is the difference between nonce and
> state? Nonce would be signed while state is not?
>
>
> Nonce would generally be generated by the entity creating the token. State
> in OAuth is generated by the client, and would only be protected if the
> client had a means to make a signed request to the server, using either a
> MAC binding or a JWT-based OIDC-style RequestObject.
>
>  -- Justin
>
> I guess I am missing some information that those in the room who voted
> "yes" had?
>
> Axel
>
> 2012/8/25 Mike Jones <[e-mail]>
>
>> I'll note for discussion purposes that a nonce and a timestamp are not
>> the same thing (although sometimes they are used to achieve similar/related
>> goals).  A nonce tends to be an opaque value that must be preserved across
>> the communication.  Whereas a timestamp typically has defined semantics -
>> sometimes simply a non-decreasing integer value - and sometimes a
>> representation of time, and then, sometimes with a uniqueness requirement.
>>
>> For discussion purposes, I'll say that the simplest thing for us to do
>> (should we decide to do anything in this regard) would be to define the
>> nonce as an opaque string value that must be preserved.
>>
>> We could also define a timestamp parameter, but as I wrote above, that
>> would likely require us to specify additional semantics - starting with
>> whether it's a non-decreasing integer or a representation of a time value.
>>  This seems much harder to define and possibly to use than a nonce.
>>
>> Would it make sense to define a nonce parameter now and hold off on
>> defining a timestamp parameter until there's a clear demonstrated use case
>> for which a nonce is not sufficient?  That would be my personal
>> recommendation.
>>
>>                                 Best wishes,
>>                                 -- Mike
>>
>> -----Original Message-----
>> From: [e-mail] [mailto:[e-mail]] On Behalf Of
>> Jim Schaad
>> Sent: Friday, August 17, 2012 12:05 AM
>> To: [e-mail]
>> Subject: [jose] POLL: Nonce/Timestamp parameter
>>
>> <CHAIR>
>>
>> If you voted at the face-2-face please do not vote again.  If you want to
>> provide comments please change the title from POLL to DISCUSS.
>>
>> Do we need to define a nonce/timestamp parameter in the base
>> specification?
>>
>>
>>
>> Room vote:  6 yes, 0 no, 1 discuss
>>
>>
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-- 
--Breno