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The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:16:18 ADT
Svend Olaf Mikkelsen (svolaf@inet.uni2.dk)
Thu, 26 Mar 1998 22:50:44 GMT
On Wed, 11 Mar 1998 23:03:55 +1000 (EST), Eric Young
<eay@cryptsoft.com> wrote in the RC5 Patent Awarded thread:
>On Wed, 11 Mar 1998, Svend Olaf Mikkelsen wrote:
>> For DES, key setup time can be traded for memory. My guess would be
>> that key setup using 32K tables can be as fast as an encryption.
>
>I'll give numbers for my library, I've compiled everything using gcc under
>linux, pentium pro 200. The key setup is always in C, the cipher speed is for
>encrypting 8 bytes in cbc mode. These numbers are only approximate, but they
>give a good approximation.
>
> set_key C asm cost
>DES 4.830uS 2.658uS 1.709uS 14.5 bytes
>3-DES 14.490uS 7.141uS 4.827uS 16.2 bytes
This is fast, and I suppose more than adequate. Having made the key
setup time = encryption time statement, I however looked at what
assembler and larger tables can do.
Using 4K tables in stead of 2K tables I was able to reduce the key
setup time on a Pentium 120 to 3.7uS compared to 3.0uS for an
assembler encryption on the same machine.
The permuted choice PC-1 is implemented with code taken from Eric
Young's libdes.
The permuted choice PC-2, is implemented with 8 7-bit lookup tables.
The code utilizes that the lookup indexes are the same for round 1, 5,
9, round 2, 13, round 3, 14, round 4, 15, round 6, 10, round 7, 11 and
round 8, 12, 16.
A libdes compatible version is available in
http://inet.uni2.dk/~svolaf/deskey1.zip
Svend Olaf
The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:16:18 ADT