Pictures of My US Army M-209-B 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 1944 in Philadelphia and is serial number 54921. The "CACH" following the serial number is the manufacturers code, which stands for the Smith - Corona Typewriter Co. It is clearly stamped with the orange Signal Corps markings with "SC 987" inside a triangle and a date stamped in red ink of Jun 16 194?. Barely visible is a previous marking of "C-213" then painted in large block lettering is: "HQ & HQ 47th Comm Sect." There are two more Signal Corps stamps, one on the bottom and the other inside the inner lid. 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.

After first receiving this cipher, I moistened the ink roller with a couple drops of water and you can see the printout on the paper tape. It looks like it is as ready for action as it was over 60 years ago.

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