A bigger problem is that PEM uses DES rather than IDEA. I just learned of a new attack by Mitsuru Matsui of Mitsubishi that requires 2^43 *known* plaintexts, not chosen ones. The note I received says that it ``breaks the scheme in 50 days on 12 HP9735 workstations''. This was presented last week at the Japanese Conference on Cryptography and Information Security.

RIPEM supports two key triple DES. Mark