Jay Prime Positive writes:
[...] If you suspect that some of the non DOD/NSA cyphers might be broken, but you are not ready to employ one-time-pads, then you should threshold you mesages into N parts so that all N are needed to recover the original. Then encrypt each part under a different cypher.
Perhaps IDEA, and 3DES would be apropriate. This will not increase the size of your messages very much since you compress before encrypting -- don't you?
Most compression programs add a characteristic signature to the beginning of the compressed output file. If a cryptanalyst guesses that you may be compressing before encrypting, wouldn't this make his job easier? To me, this sounds as though you're adding a known bit of "plaintext" to the start of each message. If you're encrypting files that you wish to store securely you could just clip off the signature, I suppose. But this would be unsuitable for sending messages, because your compression program is now incompatible with everyone else's. Or am I missing something? -- Martin Janzen janzen@idacom.hp.com