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Date: Thu, 13 Oct 2022 22:30:06 +0200
From: Solar Designer <>
Subject: Re: using john to decrypt DES hashes

On Thu, Oct 13, 2022 at 08:02:17PM +0200, Matthias Apitz wrote:
> El d??a jueves, octubre 13, 2022 a las 06:07:02p. m. +0200, Solar Designer escribi??:
> > On Thu, Oct 13, 2022 at 03:55:32PM +0200, Matthias Apitz wrote:
> > > Do I understand you correct: I yescrypt all DES strings in the database
> > > and when the user presents the PIN 4711 I first crypt the with DES and
> > > the old salt 'xX' and the result with yescrypt and the stored "$y$...."  
> > > salt and when this match the user is authenticated, correct?
> > 
> > That's correct.
> > 
> > In your example, though, a 4-digit PIN is too weak even when you use
> > yescrypt.  You'll probably want to also introduce a password policy,
> > such as by using our passwdqc.
> Thanks. I didn't wanted to stress with all details. The PIN can be upto
> 40 bytes long (minimum is 11), is broken into pieces of 8 and DES encrypted
> each part, resulting hashes are then concatenated with the salt only once
> in front of the concatenation. This is some kind of standard procedure, I don't
> remember it's name now.

Oh, this sounds similar to (but not exactly is) bigcrypt (where the
salts would be different).

Anyway, you can compute yescrypt from the concatenated descrypt hashes.

Note that while the concatenated descrypt hashes could be split back
into the individual ones and cracked just like you seem to have already
been doing, that trick wouldn't work on a yescrypt hash of them.

So you can reasonably use the upgrade approach I had suggested.


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