An authentication system endorsed by the National Security Agency that uses a PC Card as the authentication token. Fortezza is part of the U.S. government's GOSIP policy, and vendors must supply Fortezza-compliant products in order to win contracts. The Fortezza system uses the Skipjack encryption algorithm, implemented via an NSA-approved Capstone security chip. Skipjack superseded a 56-bit key based on DES encryption. The term means "fortress" in Italian. See Skipjack algorithm.