On 12/17/09 11:03 AM, Simon Josefsson wrote: > Peter Saint-Andre <[email protected]> writes: > >>>> Agreed. That's the main reason we won't deploy hashed-only on the >>>> backend plus SCRAM-only on the wire at jabber.org. >>> So will you 1) not support SCRAM at all, or 2) derive the hash keys from >>> the plaintext passwords during authentication, or 3) cache the derived >>> hash keys for a user? >> I'm not sure yet. Definitely not #1, probably #2, maybe #3. > > For #2, how many authentications happens per minute? > > My laptop does around 1.000.000 SHA-1 hashes on small data per second, > so using a 4096 iteration count leads to a limit of around 250 > authentications per second just counting the hashing. So if you aren't > anywhere near that (or can use multiple machines), the delay because of > hashing may be irrelevant.
At the jabber.org service we typically have ~15,000 users online at any one time, but they have long-lived sessions so they don't all log in at once (unless we reboot the server). I doubt that we would ever have 250 authentications per second, but on reboot we might have something like 50 or 100 authentications per second (not all SCRAM, though). > However, making sure you use the same salt for each user may be the > problematic part in some environments. Otherwise you will cause clients > to have to re-compute the keys every time too. Right, that's not very friendly. Peter -- Peter Saint-Andre https://stpeter.im/
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