Re: MD5 authentication needs help

* Tom Lane (tgl@sss.pgh.pa.us) wrote:
> Bruce Momjian  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