I really don't see the point of using a key larger than 2048 bits. Any larger key would actually be harder to factor than brute forcing the IDEA keyspace. Very little security would be gained from using a key larger than 3000 bits. Of course, one can always argue that improved factoring methods would require that an RSA public key be longer than 3000 bits to have equal security to IDEA. However, I doubt that factoring methods will improve that much.
nobody will ever need more than 640K or RAM? i wouldn't underestimate the ability of technology to grow at a pace that is beyond our wildest dreams-especially with this network serving as a virtual office/lab. of course, ymmv. <><><><><><><><><><><><><><><><><><><><><><><><><><><><><> the Forest will always be there...and anybody who is Friendly with Bears can find it. - A. A. Milne