Combined Cipher Machine

There was a need for secure inter-Allied communications, and so a joint cipher machine adapted from both countries' systems was developed by the US Navy.

The CCM was initially used on a small scale for naval use from 1 November 1943, becoming operational on all US and UK armed services in April 1944.

The adapter was a replacement rotor basket, so the ECM could be easily converted for CCM use in the field.

A specially converted ECM, termed the CCM Mark II, was also made available to Britain and Canada.

SIGROD was an implementation of the CCM which, at one point, was proposed as a replacement for the ECM Mark II (Savard and Pekelney, 1999).

CSP 1600, the replacement stepping unit to adapt the ECM Mark II to CCM
Stepping mechanism in the CSP 1600
Typex Mark 23, pictured, was similar to the Mark 22, but modified for use with the Combined Cypher Machine (CCM).