Re: MD5 authentication needs help

* Tom Lane (tgl(at)sss(dot)pgh(dot)pa(dot)us) wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > Let me update my list of possible improvements:
>
> > 1) MD5 makes users feel uneasy (though our usage is mostly safe)
>
> > 2) The per-session salt sent to the client is only 32-bits, meaning
> > that it is possible to reply an observed MD5 hash in ~16k connection
> > attempts.
>
> > 3) Using the user name for the MD5 storage salt allows the MD5 stored
> > hash to be used on a different cluster if the user used the same
> > password.
>
> > 4) Using the user name for the MD5 storage salt allows the MD5 stored
> > hash to be used on the _same_ cluster.
>
> > 5) Using the user name for the MD5 storage salt causes the renaming of
> > a user to break the stored password.
>
> What happened to "possession of the contents of pg_authid is sufficient
> to log in"? I thought fixing that was one of the objectives here.

Yes, it certainly was. I think Bruce was thinking that we could simply
hash what goes on to disk with an additional salt that's stored, but
that wouldn't actually work without requiring a change to the wireline
protocol, which is the basis of this entire line of discussion, in my
view.

Thanks!

Stephen