Robert Tappan Morris, Sr. is an employee of the National Security Agency's National Computer Security Center . He invented a trap-door encryption algorithm (now called a key derivation function) which was used for encrypting passwords stored in the /etc/password file of Unix computers during the 1980s. He is the father of Robert Tappan Morris, Jr.. There is vivid first person portrait of him in Clifford Stoll's book, The Cuckoo's Egg.