Re: Postgres: pg_hba.conf, md5, pg_shadow, encrypted passwords

Tom Lane wrote:

>It's worth pointing out also that adding a per-user-entry random salt
>to the password protocol is not some kind of penalty-free magic bullet.
>In particular it implies information leakage: I can tell from the
>password challenge (or lack of one) whether the username I have offered
>is valid. So rather than claiming "this is unconditionally a good thing
>to do", you must actually provide a credible scenario that makes the
>threat you are defending against more dangerous than the sorts of new
>threats we'll be exposed to. So far I haven't seen a very credible
>threat here.
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Ok, this made me think a bit. It's a valid point. I started off just
thinking that you would send along the stored salt with the random
session salt in something like the current AuthenticationMD5Password
message, and if the user didn't exist send something faked out. But you
would still get the information leak unless the faked out part could be
consistent (inconsistency would imply an invalid user id), so it
couldn't just be something random - you'd either have to make it
algorithmic, which would kinda defeat the purpose, or keep a dictionary
... and we're back in much the same place we came in.

cheers

andrew