(Original Review, 1981)
In the late 60's, IBM started a research project on ciphers that has produced a lot of good literature and several important cryptosystems. The effort concentrated on a family of ciphers that lent itself to high-speed implementation in hardware (one can imagine the fun second source memory manufacturers will have when the Series H uses an encryption protected fiber optic bus). In January 1976, one of these systems was adopted by the National Bureau of Standards (NBS) as the federal Data Encryption Standard (DES) on sensitive but unclassified data.
If you're into stuff like this, you can read the full review.