I'd say that where a verifier is required, only a small number of attempts
should be allowed.  We should allow for user entry error while mitigating
against brute force attacks.
--
Andrew Arnott
"I [may] not agree with what you have to say, but I'll defend to the death
your right to say it." - S. G. Tallentyre


On Sun, Jun 7, 2009 at 4:34 AM, Morten Fangel <[email protected]>wrote:

> What about trying to swap a Request Token to a Access Token, but the
> verifier code is wrong.
> Does that invalidate the Request Token, or does it just fail and wait
> for a new request with the correct verifier code?
>
> If it doesn't invalidate the Request Token, couldn't an attacker to try
> all options for verifier codes? If the Request Token is requested with
> an OOB callback, the verifier will usually be sort so people don't have
> to manually enter a long string.
>
> Regards
> Morten Fangel
>
> On Jun 7, 2009, at 7:17 AM, Eran Hammer-Lahav wrote:
>
> It means that once an Access Token was given using a Request Token, that
> Request Token must not be used again – it is invalidated.
>
> EHL
>
>
> On 6/6/09 9:45 PM, "Andrew Arnott" <[email protected]> wrote:
>
> In section 6 of the OAuth spec (either 1.0 or 1.0a versions -- they're the
> same here), I see the following:
>
> Request Token:Used by the Consumer to ask the User to authorize access to
> the Protected Resources. The User-authorized Request Token is exchanged for
> an Access Token, *MUST only be used once*, and MUST NOT be used for any
> other purpose. It is RECOMMENDED that Request Tokens have a limited
> lifetime.
>
> I'm wondering what this "MUST only be used once" is intended to limit.  Is
> it sufficiently compliant to say that the SP will only ever give out the
> Access Token for a given request token once?  Or does it mean that a desktop
> consumer app cannot keep polling the server with its request token until it
> finally gets an access token when the user finishes authorizing the request
> token?
>
> --
> Andrew Arnott
> "I [may] not agree with what you have to say, but I'll defend to the death
> your right to say it." - S. G. Tallentyre
>
>
>
>
>
>
>
>
> >
>

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