 is available to most anyone who wants to read about it. As a matter of fact, there was a guy who pretty much put the United States in front in cryptography. His name was William Friedman, F-R-I-E-D-M-A-N. His wife was a superb cryptographer as well. If you're seeing a book about the woman who broke codes, it was probably Friedman's wife. But he set up some principles, and these are the principles.