Saturday, March 31, 2018

The IBM Codatype cipher machine

In the files of the NSA’s Friedman collection there is a report by William F. Friedman, dated September 1937, which deals with a cipher machine called Codatype (1). 

Apparently David Salmon, the State Department’s chief of the Division of Communications and Records wanted Friedman’s opinion on the security afforded by the Codatype machine.

Although the device appeared to be ‘highly reliable, speedy and efficient’ Friedman’s conclusion was that ‘the degree of cryptographic security afforded by the machine is relatively low, and certainly not sufficient for governmental confidential or secret messages’ and ‘It is doubtful whether anything can be done to eliminate the more or less fatal cryptographic weakness of this model and still retain a machine and cryptographic system which will be practical for the purpose for which intended’.

Thus the Codatype remained a prototype and was not acquired by the State Department.

The device was designed by the IBM engineer Austin Robert Noll, US patent 2,116,732 (2):



  1. I was searching Google for Codatype and I found another reference for using Codatype with SIGABA -

    1. This probably refers to a radio transmission device attached to the SIGABA cipher machine, not the 1930's cipher machine.