john-dev - Re: Bit slice implementation of DES based hashes

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Message-ID: <CAG5=z91yq8WcpEzndXYzQpep5SOaBVLW4-Eyj8AF70k3AiTpLQ@mail.gmail.com>
Date: Tue, 17 Jan 2012 06:37:15 +0530
From: Piyush Mittal <piyush.cse29@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: Bit slice implementation of DES based hashes

Hello,

I am not getting exact source of segmentation fault so I need to know exact
process of key initialisation. Let us suppose I have  key
"\x80\x11\x22\x33\x44\x55\x66\x77"  then how DES_bs_set_key() is setting
the 768 key bit (i.e key for each round) using the code below. Please tell
me as brief possible specially role of s1 and s2.



                s1 = DES_bs_all.s1[xor];
                s2 = DES_bs_all.s2[xor];
                *(ARCH_WORD *)((char *)k + s1) ^= mask;
                if (s2 > 8) break; /* Required for xor == 0 */
                xor >>= s2;
                k[s2] START ^= mask;
                k += s2;
                if (!xor) break;
                s1 = DES_bs_all.s1[xor];
                s2 = DES_bs_all.s2[xor];
                xor >>= s2;
                *(ARCH_WORD *)((char *)k + s1) ^= mask;
                k[s2] START ^= mask;
                k += s2;





Thanks
-- 
Piyush Mittal

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