>>>>> I??aki Baz Castillo <[EMAIL PROTECTED]> wrote:

> Well, RFC 3261 says:

>    22.4 The Digest Authentication Scheme
>       8 - ...
>           However,
>           servers MUST always send a "qop" parameter in WWW-Authenticate
>           and Proxy-Authenticate header field values.  If a client
>           receives a "qop" parameter in a challenge header field, it
>           MUST send the "qop" parameter in any resulting authorization
>           header field.

Note that there are too many proxies that does not send and count
qop, so client really shall compute authorization also for variant
without qop.

For simple but working implementation, it's enough for UAS to
generate nonces cryptographically randomly, keep a few last nonces
and expire them periodically to protect against any replay attack
later than nonce expiration. More complicated implementation shall
keep nonce sent to each client separately... this can be too
expensive.

-- 
Valentin Nechayev
PortaOne Inc., Software Engineer
mailto:[EMAIL PROTECTED]
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