-----BEGIN PGP SIGNED MESSAGE----- On Sat, 1 Jun 1996 anonymous-remailer@shell.portal.com wrote:
But then you still have the problem of identifying the contents. If there were no headers, one could not tell if the message was compressed using ZIP, LHA, StuffIt, tar*, compress, gzip, Alice's Magical Supercompressor, or even if it was left alone. One could also not tell if the decryption happened successfully.
OK, I think I misunderstood. You were talking about encrypting a file that has already been compressed and I was talking about an encryption program that would compress then encrypt. In the latter case, headers would be completely unnecessary, whereas in the former, they are necessary. Generally, checksums or parity bits are much better ways of checking if the decryption was successful. While this does make cryptanalysis easier, a known-plaintext will not work. - -- Mark =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= markm@voicenet.com | finger -l for PGP key 0xe3bf2169 http://www.voicenet.com/~markm/ | d61734f2800486ae6f79bfeb70f95348 "In Christianity neither morality nor religion come into contact with reality at any point." -- Friedrich Nietzsche -----BEGIN PGP SIGNATURE----- Version: 2.6.3 Charset: noconv iQCVAwUBMbEWH7Zc+sv5siulAQFA0gP9FMd68l1J8K12FDLkx5+p5j0TwrAlCLn0 cqSHVouOw2mhqk1LEgxMBPuI+6Vw2Bnzhj8QxDz7Qjjs98Jqu4p+4ky9FLzVn4vh oGi2j/W0P1onLi4bSoq6u1SE8vPCNRresTox36DMWOMSN4Lxybx363xDx+8vD627 5D9n3fW5e/0= =V+t3 -----END PGP SIGNATURE-----