Pictures of My US Army M-209-A Cipher

This entirely mechanical cipher machine was designed by Boris Hagelin and was similar to his C-38 cipher. After simplifying the design and making it more rugged, production began in 1942 and by the end of WW2 over 140,000 M-209s were made at a cost of $64.00 each. The Navy version of this cipher was called the CSP-1500. It was popular for its light weight, small size and ease of use. It was never considered a secure cipher, so it was used for tactical, battlefield messages where the intent was only to delay the enemy in reading the message by a few hours.

It has 6 fixed rotors with a mutually prime number of settings (26, 25, 23, 21, 19, 17), giving a maximum message length before repeating the cipher of over 101 million. Behind the rotors is a large drum which is used to set the points which would step each of the rotors, allowing for highly irregular stepping. Twisting a lever switched between "C" cipher mode or "D" decipher mode. The letter Z was reserved to print out a space in decipher mode.

The pictured machine was made in 1942 in Philadelphia and is serial number 214, making it one of the earliest of the 140,000 manufactured during WW2. There are Signal Corps stamps inside the inner lid and on the bottom of the machine. Inside the lid is the decal "Manufactured By L C Smith & Corona Typewriters Inc." The paper tape roll is in the lid as is a pair of tweezers and an aluminum tube holding spare ink rollers, which is stamped "I" on the top. The slotted tip screwdriver and tube for oil is missing, as is one of the 4 rubber feet.

There are a few minor cosmetic differences between the M-209-A and the M-209-B. The last few pictures compare these two cipher machines to show those differences side-by-side.

Click on thumbnail for screen-size picture, then click on button on lower right for mega-size picture
     

     

     

     

     

     

Differences between the M-209A and M-209B Cipher Machines