Date: Wed, 2 Nov 2005 12:59:30 -0600
From: Bruno Wolff III <bruno@wolff.to>
To: "Mark R. Dingee" <mark.dingee@cox.net>
Cc: pgsql-sql@postgresql.org
Subject: Re: PGSQL encryption functions
Message-ID: <20051102185930.GA10108@wolff.to>
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	"Mark R. Dingee" <mark.dingee@cox.net>, pgsql-sql@postgresql.org
References: <200511011438.06610.mark.dingee@cox.net>
	<20051101212844.GA24861@wolff.to>
	<200511011700.50776.mark.dingee@cox.net>
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On Tue, Nov 01, 2005 at 17:00:50 -0500,
  "Mark R. Dingee" <mark.dingee@cox.net> wrote:
> Bruno,
> 
> I use an authenticate() function as a part of state maintenance in a PHP web 
> app.  In the function, I generate an encrypted token that is then used in the 
> validation process on subsequent pages.  md5 works, but I've been able to 
> brute-force crack it very quickly, so I'm looking for an alternative.  Any 
> thoughts would be greatly appreciated.

This isn't a problem with MD5. While MD5 does have some theoretical weaknesses,
they aren't really an issue in this case.

Why are you using a hash at all? If you are using the hash as a key, why not
just use a random string instead? The web browser could be handed a session id
and random string and on the server you would have a table indexed by session
ids that includes the random string.

On many systems you can use /dev/urandom as a source of random data. Since
you don't seem to be concerned about sniffing, /dev/random is probably overkill
and having it block when low on entropy would probably be a problem for you.