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

From: "Jim C(dot) Nasby" <decibel(at)decibel(dot)org>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Stephen Frost <sfrost(at)snowman(dot)net>, pgsql-hackers(at)postgresql(dot)org, bugtraq(at)securityfocus(dot)com
Subject: Re: Postgres: pg_hba.conf, md5, pg_shadow, encrypted passwords
Date: 2005-04-20 21:23:23
Message-ID: 20050420212323.GT58835@decibel.org
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On Wed, Apr 20, 2005 at 05:03:18PM -0400, Tom Lane wrote:
> > This would allow for the pregeneration of the entire md5
> > keyspace using that 'salt' and then quick breakage of the hash once
> > it's retrieved by the attacker.
>
> Considering the size of the possible keyspace, this is pretty silly.

Actually, it's not as silly as you think. You can download rainbow
tables for Windows/LanMan passwords up to 14 or 15 characters in length.
Given the password hash and some code, you can determine the user's
password in a matter of minutes.

Simply put, MD5 is no longer strong enough for protecting secrets. It's
just too easy to brute-force. SHA1 is ok for now, but it's days are
numbered as well. I think it would be good to alter SHA1 (or something
stronger) as an alternative to MD5, and I see no reason not to use a
random salt instead of username.
--
Jim C. Nasby, Database Consultant decibel(at)decibel(dot)org
Give your computer some brain candy! www.distributed.net Team #1828

Windows: "Where do you want to go today?"
Linux: "Where do you want to go tomorrow?"
FreeBSD: "Are you guys coming, or what?"

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