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Date: Mon, 23 Jan 2012 22:40:33 +0530
From: Piyush Mittal <>
Subject: Re: Bit slice implementation of DES based hashes

> Exact sequence as what you see in the book?

In the book an example with full description is given, through that I was
matching the sequence.

 Is that "Cryptography and Network Security" by Behrouz A. Forouzan?


If you're referring to oracle_fmt_plug.c: oracle_init(), then it has the
> parity bits in its specified key dropped by the DES_set_key() call.  We
> need to implement an equivalent of this, which we may do by adjusting our
> specified key value as I had proposed (no need for any runtime overhead).
> Things are trickier with these lines, also in oracle_fmt_plug.c:
>        DES_ncbc_encrypt((unsigned char *)cur_salt, buf, l, &desschedule1,
> (DES_cblock *) crypt_key, DES_ENCRYPT);
>        DES_set_key((DES_cblock *)crypt_key, &desschedule2);
> I think what you need to do here is to apply the normally-excluded (in
> JtR's code) DES final permutation between these two steps.

I am not talking of SSL Des, I am considering bitslice Des that I am
making, In that I am calling DES_bs_set_key() using the key
"\x80\x11\x22\x33\x44\x55\x66\x77" (after parity drop) as you told me in
previous posts. But here my question is that why we have taken this key
after parity drop? Even though we have already used parity drop in
DES_bs_init() ?

Piyush Mittal

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