At 09:52 AM 1/22/96 -0800, Jonathan Zamick <JonathanZ@consensus.com> wrote:

Right now I'm trying to convince Ascom to develop a crippled version of IDEA to simply give away if anyone wants it for export. (Like most of the folk here, I don't see a 40 bit key as very valuable, but it is useful for companies which don't have contacts in Europe.)

A crippled version is easy - generate a 128-bit random key, make 88 bits available as salt, leaving 40 hidden bits. The problem is how to make the salt-bits available without interfering with applications and protocols. If you wanted a 64-bit crippled version, most applications need 64 bits of IV anyway, so you could use 64 bits of salt for that, leaving 64 more. To do a 40-bit version, you _could_ use 64 bits of salt and wire down the other 24 bits into a well-known pattern instead of choosing them randomly. That's three characters of ASCII, and I'd suggest "NSA" as the obvious pattern :-) So generate your 128-bit random number, replace the first 24 bits with "NSA", copy the 64 bits into the IV, and use it for your key. #-- # Thanks; Bill # Bill Stewart, stewarts@ix.netcom.com, Pager/Voicemail 1-408-787-1281 # # "Eternal vigilance is the price of liberty" used to mean us watching # the government, not the other way around....