
Gee. Say they feed the 80-bit key through Snefru-8 and take the first 60
bits of the result, then use those 60 bits as the real key. How do you
figure out that each key is one of 2^20 ``equal'' keys? You can try a
birthday attack, but if the key can be changed only once a second then
you will need several lifetimes to get reliable statistics. Somehow I
don't think you could catch the NSA at this sort of skulduggery.