M-209 - The book

M-209 homepage
1st Ch.: Introduction
  1. Problems
  2. Solutions
  3. Explanations
2nd Ch.: Single Wheel
  1. Problems
  2. Solutions
  3. Explanations
3rd Ch.: Two Wheels
  1. Problems
  2. Solutions
  3. Explanations
4th Ch.: Three Wheels
  1. Problems
  2. Solutions
  3. Explanations
5th Ch.: Four Wheels
  1. Problems
  2. Solutions
  3. Explanations
6th Ch.: Five Wheels
  1. Problems
  2. Solutions
  3. Explanations
7th Ch.: Indicators unciphered
  1. Problems
  2. Solutions
  3. Explanations
8th Ch.: Six Wheels, crypto alone
  1. Problems
  2. Solutions

Barker's Book

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.

Presentation

The 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.

References

  • “Cryptanalysis of the Hagelin cryptograph”, by Wayne G. Barker, Aegean Park Press (1977).
  • "Classical Cryptography Course, Lesson 21 : Cryptanalysis Of The Navy CSP 1500 Cipher Machine [Hagelin C-38 Family]", by Randy Nichols (LANAKI).