Gjøvik University College Cryptology 1

1 Introduction

The first rotor cipher machines were developed at the end of WW1, including the one that after some modifications would become the most famous of them all, the Enigma. It was invented by Arthur Scherbius, and cryptanalyzed at Bletchley Park during WW2. But there was another less famous rotor machine, which was just as important during WWII, the Swedish Hagelin M-

209. 
     Produced in a stunning amount of approximately 140000, and used mainly by the US Army and Navy, but also by other allied nations, like Norway.
     

This paper will first give a short introduction to cryptographic rotor machines, describe the history of Boris Hagelins cipher machines, starting in 1925, leading up to the M-209 in WW2, the successors of this complex little machine, and ending in the 1960s, when the electronic age was entered. The text will then discuss details of the M-209s, its mechanical properties, how its ciphering works, how to use it, and at last a part about cryptanalysis work done on it.