Re: BUG #4876: author of MD5 says it's seriously broken - hash collision resistance problems

"Meredith L. Patterson" <mlp@osogato.com> writes:
> Magnus Hagander wrote:
>> We might want to consider using a safer hash for the password storage at
>> some point, but from what I gather it's not really urgent for *that* use.
>>
> It would be a lot more urgent if we weren't salting, but IIRC we are.

I don't really see that there's any issue here at all.  The point of the
hashing is to prevent a superuser (non-superusers can't look at the
stored hashvalue anyway) from recovering the user's actual password.
This is not for the purpose of protecting the database itself ---
superusers already have all the keys to the kingdom in that respect.
It's only meant to protect a user who's unwisely used the same password
for multiple services from having a database breakin mean that his other
services are compromised as well.

Being able to make up strings that hash to the same thing doesn't create
a vulnerability of this sort, AFAICS.  You've found something that the
database would accept as being a valid password, but that doesn't mean
that it will work for other services.

            regards, tom lane