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Re: DES Key Decryption Time

From: Slawek (sgptelsatgp.com.pl)
Date: Wed Apr 09 2003 - 14:09:33 CDT


Valdis.Kletnieksvt.edu wrote:

>> In hardware you can unroll the loop and use pipelining giving even 1 cycle
>> per 1 block of data (not to mark about paralel processing which is easy with
>> today's FPGAs).
>
> Well.. one externally visible cycle - if you unroll the loop you need to either
> have 16 cascading stages that use async logic or timing signals to keep all the
> bits in sync. ;)

You have n hardware gates making simple operations each with proper latches as needed, all latches use the same clock signal. One data is encoded in L cycles, but a new data set is started in every one cycle.

So yes - processing of one dataset takes L cycles, but processing for example 1G datasets takes 1G +L-1 cycles.

--
Slawek