A block cipher algorithm designed by the National Security Agency as part of the Capstone chip used in the Fortezza PCMCIA cards, the Clipper chip, and also for the Defense Messaging System. In the taxonomy of ciphers it is an unbalanced Feistel network with a block size of 64 bits, an 80-bit key, and 32 rounds. The key escrow features the Clipper Chip was infamous for are not embodied here, but in the protocol used by the chip. The NSA considers it a "high risk algorithm", meaning they considered it likely that it be reverse engineered, so it's improbable that they used their most clever and secret design methodologies to make it. It was declassified in 1998 and specifications are available from NIST and public domain code implementations are available all over the Internet.