RSA put up encrypted messages in 40,48,56,...128 bit keys and 56bit des.
They offer prizes to the people who can break it. Basically RSA gets
to pay a small amount to prove a) small keys are crap (US export politics)
and b) large keys are very secure (contracts, money, more orders for them
etc).
The messages are known to be plaintext and start with known text.
The 40 bit key was broken easily, the 48bit key was done by a mass compute
effort. 56bits is now being tried by a different group - the 56bit one
is breakable from a practical general point of view - its an exercise
in hack value and being the largest number crunch attempted by man.
(BTW if all the spare CPUtime in the world was used it looks like it
would take only hours maybe minutes to break it) - there is a lot of
idle time in the world today
Alan