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Subject: Re: q&d comparison (was Re: [Cryptix-Users] Rijndael - the real work now begins)
From: Bill Stewart (regsupportnetscape.com)
Date: Sun Oct 08 2000 - 14:05:58 CDT

Does "90% faster" than DES mean "Rijndael takes 10% as long
as DES" or "DES takes 190% as long as Rijndael"?

Also, since DES isn't strong enough, comparing Rijndael speed
to 3DES is more appropriate - which says Rijndael has a significant
speed advantage.

Ben Laurie commented on 3DES really only having 112 bits of strength -
but for this question, which is how much entropy you need for your keys,
168 bits is the right answer.

At 12:32 PM 10/8/00 -0400, Ian Grigg wrote:
>Fred Baube wrote:
>> Would someone like to make a quick 'n dirty comparison among
>> DES, 3DES, and Rijndael in terms of key entropy required and
>> processing time required ? Give us all some quantifiable
>> motivation to switch ASAP ...
>
>There is plenty of stuff on the NIST site, but you'd have to dig
>for it. There are lots of comparisons in the NSA report.
>
>Some early results say that Rijndael is about 40% (256) and 90%
>(128) faster than DES in encryption (decryption is slightly
>slower than those speedups).
>
>Key set up is about 5 times faster than DES (encryption) and
>3 times faster than DES (decryption) with some drop off (4, 2.5)
>for 256 bit keys.
>
>On the amount of entropy, well, I'd leave that to a cryptographer,
>other than the observation that Rijndael has 128, 192, 256 bit keys,
>whilst DES has 56 bits and T-DES has 168 (full).

                                Thanks!
                                        Bill
Bill Stewart, bill.stewartpobox.com
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