# Re: DES doubts. why we use 56 bit key when ony 48 bits are used?

*From*: fermisoft@xxxxxxxxx*Date*: 29 Dec 2005 02:22:36 -0800

One more doubt. Why the first and last permutations in a round are

susceptible to the attack? In most of the DES crypto analysis, they

are simply ignoring the first and last permutations. Why is this?

.

**Follow-Ups**:**Re: DES doubts. why we use 56 bit key when ony 48 bits are used?***From:*tomstdenis

**References**:**DES doubts. why we use 56 bit key when ony 48 bits are used?***From:*fermisoft

**Re: DES doubts. why we use 56 bit key when ony 48 bits are used?***From:*tomstdenis

**Re: DES doubts. why we use 56 bit key when ony 48 bits are used?***From:*fermisoft

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