have you considered
des | tran | des | tran | des ?
My point is that you can get the same level of security with much less effort/computation. BTW, am I incorrect in my belief that the additional security provided by the 32 bit shifting TRAN operation suggested for the 3DEA hardly provides any additional security? (i.e. if they could break 3 IDEA operations or 3 DES operations, they can break them with 32 bit shifting TRAN operations interleaved in just about the same amount of time.) It looks like it would make meet-in-the middle attacks take up substantially more memory and make identifying successful decryptions slightly more difficult, but for security against nearly brute force there isn't much difference between 2^(47) and 2^(47.2) operations. JWS