john-dev - des-bs-doubt

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Message-ID: <1365280935.60086.YahooMailNeo@web140903.mail.bf1.yahoo.com>
Date: Sat, 6 Apr 2013 13:42:15 -0700 (PDT)
From: deepika dutta <deepikadutta_19@...oo.com>
To: "john-dev@...ts.openwall.com" <john-dev@...ts.openwall.com>
Subject: des-bs-doubt

Hi,

I want to know the reason behind using the following representation of key and plaintext in bitsliced des.

For plaintext: Swapping the 32 bit halves before doing encryption though in the DES standard these halves are swapped after the last round.

For key: Storing the 7 bits per byte in little endian form in DES_bs_all.K

Is there any performance issue in this? If I want to swap the plaintext after last round and store the 7 bits per byte in big endian form in DES_bs_all.K, then will there be any problem in this representation? (of course I would have to change the indexes of B and K referred in sbox functions).  

Thanks,

Deepika
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