Typex
This eliminated an entire class of attacks on the system, whereas Enigma's fixed notches resulted in certain patterns appearing in the cyphertext that could be seen under certain circumstances.
On some models, operators could achieve a speed of 20 words a minute, and the output ciphertext or plaintext was printed on paper tape.
[citation needed] By the 1920s, the British Government was seeking a replacement for its book cipher systems, which had been shown to be insecure and which proved to be slow and awkward to use.
Over a period of several years and at large expense, the committee investigated a number of options but no proposal was decided upon.
Lywood worked with J. C. Coulson, Albert P. Lemmon, and Ernest W. Smith at Kidbrooke in Greenwich, with the printing unit provided by Creed & Company.
For inter-Allied communications during World War II, the Combined Cipher Machine (CCM) was developed, used in the Royal Navy from November 1943.
The CCM was implemented by making modifications to Typex and the United States ECM Mark II machine so that they would be compatible.
This amalgamation allowed a single operator to use punch tape and printouts for both sending and receiving encrypted material.
In 1944 the Admiralty decided to supply 2 CCM Mark III machines (the Typex Mark II with adaptors for the American CCM) for each "major" war vessel down to and including corvettes but not submarines; RNZN vessels were the Achilles, Arabis (then out of action), Arbutus, Gambia and Matua.
[5] Although a British test cryptanalytic attack made considerable progress, the results were not as significant as against the Enigma, due to the increased complexity of the system and the low levels of traffic.
A Typex machine without rotors was captured by German forces at Dunkirk during the Battle of France and more than one German cryptanalytic section proposed attempting to crack Typex; however, the B-Dienst codebreaking organisation gave up on it after six weeks, when further time and personnel for such attempts were refused.
The following is a summary of information so far received on German attempts to break into the British Typex machine, based on P/W interrogations carried out during and subsequent to the war.
It is divided into (a) the North African interrogations, (b) information gathered after the end of the war, and (c) an attempt to sum up the evidence for and against the possibility of German successes.
Apart from an unconfirmed report from an agent in France on 19 July 1942 to the effect that the GAF were using two British machines captured at DUNKIRK for passing their own traffic between BERLIN and GOLDAP, our evidence during the war was based on reports that OKH was exploiting Typex material left behind in TOBRUK in 1942.
The German equivalent teleprinter machines in World War II (used by higher-level but not field units) were the Lorenz SZ 40/42 and Siemens and Halske T52 using Fish cyphers.
