On Sun, 7 May 2000, Tom Lane wrote:
> Vince Vielhaber <vev@michvhf.com> writes:
> >>>> My intent was not to send the username, but let the server figure it
> >>>> out by the response.
> >>
> >> That would be a neat trick. How will you do it? MD5 is not reversible.
>
> > CLIENT: md5(salt_from_server + md5(username + md5(password)))
>
> > SERVER: md5(salt_from_server + md5(username + stored_password))
>
> > The server runs thru all available usernames using the above algorithm.
>
> No, that doesn't work unless stored passwords contain no random salt
> at all (you could use the username alone, but as I previously said
> that's no substitute for random salt, and of dubious value anyway).
> That'd be a distinct *loss* in security, not an improvement.
>
> To have salt in the stored passwords, the server must receive the
> username first so that it can look up the pg_shadow entry and find
> which stored salt to send to the client (along with the randomly
> generated per-transaction salt). You could cloak the username as
> I suggested before, but there have to be two messages.
You're right, it wouldn't work. It should've been like this:
CLIENT: md5(salt_from_server + md5(username + password)))
SERVER: md5(salt_from_server + stored_password)
The "salt_from_server" is your random salt. The fixed salt is the
username.
Vince.
--
==========================================================================
Vince Vielhaber -- KA8CSH email: vev@michvhf.com http://www.pop4.net128K ISDN from $22.00/mo - 56K Dialup from
$16.00/moat Pop4 Networking Online Campground Directory http://www.camping-usa.com Online Giftshop
Superstore http://www.cloudninegifts.com
==========================================================================
