Horst Feistel: the inventor of LUCIFER, the cryptographic algorithm that changed cryptology

This paper documents the early life of Horst Feistel, in particular, the events shaping his career. His creativity led to the development of today’s high-grade cryptographic algorithms. We describe Feistel’s successful escape from Nazi Germany, his university training in physics in Zürich and in Boston, and the career change to cryptography. Feistel became a Research Staff Member at the IBM Thomas J. Watson Research Center in Yorktown Heights, New York, in 1968. The cryptographic algorithm LUCIFER encrypts data to secure their contents. It embodies the ideas intrinsic in Feistel’s 1971 IBM patent. Claude Shannon’s 1949 prescription for achieving ideal secrecy was the basis for LUCIFER and its successors DES, 3DES and AES. DES authenticated transactions in the automated teller machine system developed by IBM as part of the Lloyds Bank Cashpoint System in England. Public key cryptography and advances in communication networks would provide a means to secure credit card transactions and lead to a lucrative environment for E-Commerce. The availability of high-grade encryption appears to have drastically limited the National Security Agency’s Signals Intelligence mission. The Department of Justice’s dispute with Apple’s iPhone is an attempt to restrict the commercial availability of high-grade encryption algorithms. It signals the struggle between privacy and national security.