At 11:05 PM -0800 6/24/98, Anonymous wrote:
NSA made a claim that Skipjack couldn't be extended past 80 bits of key. Most plausible explanation to my mind is that they're lying. Second is that there is an attack against a class of Skipjack-like ciphers that requires only a few plaintexts and 2^80 operations. Third is that some common key-lengthening tricks like those for 2-key-3DES, DES-X, and DEAL fail when applied to Skipjack. I can hardly fathom one resistant to all three, but I guess it's possible with NSA.
3DES is useful because DES does not form a group. To the best of my knowledge, Skipjack has not been analysed in this area (outside of Never Say Anything). ------------------------------------------------------------------------- Bill Frantz | If hate must be my prison | Periwinkle -- Consulting (408)356-8506 | lock, then love must be | 16345 Englewood Ave. frantz@netcom.com | the key. - Phil Ochs | Los Gatos, CA 95032, USA