Solving Cipher Problems

by Frank Lewis

With particular clarity this book covers virtually every possible classical cipher system. With 30 years experience as a professional cryptanalyst-- including WWII years when he was the key figure in the breaking of Japanese military codes--Frank W. Lewis is extremely well qualified to write what is perhaps the finest book ever written concerning the practical solution of classical cipher systems. Text includes problems for the student. For the historian, the text abounds with narrative memoirs and tales of cryptanalysis and personalities, plus twelve pages of pictures.

250 pages, Paperback

First published January 1, 1992

Reviews

[Richard Bean · Rating 5 out of 5]

Frank Lewis, a famous cryptographer, crossword and puzzle writer, goes through the ACA (American Cryptogram Association) cipher types and explains, with examples, how a manual solver would tackle them, and his thought process.

There are also important chapters on probabilities and diagnostics. This last topic goes beyond the usual ACA puzzles and work; and I have only really seen this kind of writing in Callimahos's "Military Cryptanalytics Part III" (1977) - made public in a redacted form in 2021. It is not too mathematical, but it goes far beyond the last two pages in Gaines (1939) on a similar topic.