The data consists of pairs of plaintext/ciphertext generated by a key given in the file 'key' (the bits set to 1 are given as fact key(n) and other bits are set to 0).

There is a file for each pair. The files have names of the form pc-pair.Rr.P where 'R' is the number of rounds of DES used for encryption and 'P' is a sequence number of the pair.

Hence, a file pc-pair.3r.2 contains the second pair of a plaintext and the corresponding ciphertext encrypted using DES with 3 rounds and using key in file key. The ciphertext and the plaintext are given in the form of facts stating the bits set to 1 and all other bits are set to 0.

For example, in pc_pair.1r.1:

For the plaintext bits 1 to 7 are set 0 but bits 8 and 9 are set 1
and similarly, for the ciphertext bits 1 to 3 are set to 0 but bit 4 is
set to 1 etc.

There ten pairs for four versions of DES with 1, 2, 3, and 4 rounds,
respectively.

Developed by Ilkka Niemela/Ilkka.Niemela@hut.fi