re clipper considered harmful the clipper chip s user key is formed by r e d e n s s s r e d e n s s s r e d e n s s s why is the triple encrytion used is it just to gain an effective increase in keyspace to defeat a potential keysearch if so why use bit keys not knowing anything about the skipjack algorithm it s not really possible to guess whether this makes it harder or easier to guess s s why are n n and n formed as they are it would be facinating to see the skipjack algorithm to look for ways of attacking it that require three ciphertext blocks formed in that odd way where do the bit constant values that are concatenated with the serial number to form n n n come from are they changed from chip to chip or session to session even if they re published in the ny times if skipjack is resistant to known plaintext attacks when using triple encryption then there s no break in security but why allow that kind of weird format if those three bit values are truly random bits then maybe it s used to ensure that a known plaintext attack on skipjack if it exists can t be easily used to derive s and s for a whole production run of these chips does dorothy denning read this group if not is someone on the group forwarding questions like these to her or martin hellman or anyone else who s seen more details about the chip john kelsey
