Just a quick question on the keysize of the CAST algorithm. According to the bible of Bruce, CAST uses a 64 bit keysize, while in the manual of PGP 5.0 (page 89), Phill states that CAST uses a 128 bit keysize...

Am I missing something?

"CAST" isn't a particular algorithm, but a design process for creating algorithms. The particular CAST instantiation used in PGP 5 is either CAST-128 or CAST5, depending on who you ask. Other versions of CAST abound, including an earlier one used by MS for unknown purposes which had a 64-bit key, probably the one Bruce is referring to. Peter.