1st Ch.: Introduction
3rd Ch.: Two Wheels
5th Ch.: Four Wheels
7th Ch.: Indicators unciphered
I have learnt how to solve messages ciphered by M-209 thanks to a wonderful book : “Cryptanalysis of the Hagelin cryptograph” written by Wayne G. Barker. Unfortunately it is difficult to get it.
Happily, Randy Nichols (LANAKI) former president of ACA wrote a white paper (Lesson 21) about cryptanalysis of CSP-1500 (Navy version of M-209). This text is largely based on Barker's book. Unfortunately it doesn't contain any exercices. In Barker's book, the exercices are very useful to test our understanding.
It is the reason I decided to publish on this Web Page a booklet (named "The book") which contains exercises very similar to Baker’s. But with two improvements: I give solutions and some hints to help solving hard exercices.
PresentationThe book gives many problems with a growing difficulty. Solutions and explanations are given. One starts with cipher machine having only one wheel. Then two wheels, and so on up to six wheels. Each time, different kind of problems are proposed: messages in depth, the same message encrypted with different keys, the beginning or end of messages is known, probable words are given. So you can be faced with all possible situations.