h Yes, 40 bits would be too little, especially since you can probably tell if you've got the correct key by the form of the data, but they're actually generating your 80-bit key as the XOR of two other 80-bit numbers, and searching 2**80 still takes reasonably long. Unfortunately, the method of generating the two 80-bit numbers is disturbingly suspect; see articles in sci.crypt and alt.privacy.clipper posted by Steve Bellovin and somebody with email from Martin Hellman and Dorothy Denning. Bill Stewart