Cryptography old and new

Classical cryptographic schemes which were in use prior to World War II are described and illustrated. Several factors are identified which have contributed to the marked difference between old and new cryptography, including: the computer, the need for cryptography in the public sector, advances in communications technology, and the need for standardization. The Data Encryption Standard (DES) of the National Bureau of Standards is discussed. This tutorial ends with a summary of the recommendations of the Public Cryptography Study Group, which was formed by the American Council on Education at the urging of the National Security Agency.