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Weakness of Enigma[edit]

"Their inability to use the machine in order to crack Typex messages may have convinced them even more of the security of Engima."

the Abwehr specialists knew of the weakness of enigma. They concluded, however, that no one would be able to orchestrate the effort to actually achieve decyphering.


Does any have access to:

  • Ralph Erskine, "The Development of Typex", The Enigma Bulletin 2 (1997): pp69-86

— Matt 02:27, 2 Aug 2004 (UTC)

Removing for now[edit]

[3->5 rotors]...This change alone adds no security, because a rotor only turns after enough key presses have occurred to turn all the rotors to the left of it. In the case of a three-rotor machine that would require 26 × 26 = 676 key-presses before the third rotor would have any effect. In the case of a four-rotor machine the message would have to be 676 × 26 = 17576 letters long — and messages this long simply were not sent.

Simply adding extra rotors can add security — the security doesn't just depend on the period of the machine; increasing the number of rotors increases the number of possible keys, and would likely make most attacks more complex. For example, a bombe would have a lot more work to do with five rotors than with three. — Matt 23:06, 1 Sep 2004 (UTC)

Didn't the later German naval version of Enigma (which was harder to crack) use four rotors rather than three? Hugo999 (talk) 20:27, 4 January 2020 (UTC)Reply[reply]

Replaced book ciphers?[edit]

In the late 1920s the British were seeking a replacement for their book cipher systems...

Is the author suggesting that book ciphers were used in the British services at this time, or is this a thinko for code books? Securiger 14:00, 27 Nov 2004 (UTC)

Yes, I would think that codebooks is what was intended. — Matt 18:24, 27 Nov 2004 (UTC)

Typex usage[edit]

By far the greatest difference from Enigma was to simply use Typex as little as possible. Whereas the Germans routinely encrypted almost all of their messages in their various networks using Enigma, only the British Army high command and the RAF, used the Typex regularly. Other branches still performed all of their encryption by hand using older book-based methods. The supply of the Typex machines was kept severely limited, and no field units were ever allowed to have machines.

Some problems; Typex was also used by the Royal Navy (see my ref to 1940 RN circulars in article), although it took them a while to roll it out. There were, according to Ralph Erskine (ref'd in the article) serious problems with manufacturing sufficient numbers of Typex. Erskine attributes some of the security of Typex to the fact that each network used a different set of rotors with their own wiring. Germany used largley the same set of rotors for all its Enigma networks. — Matt Crypto 21:38, 16 October 2005 (UTC)Reply[reply]

As I have added to the article, in 1944 the 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, Arbutus, Gambia and Matua. [1] so initial restrictions were more a matter of supply. Archives NZ file references:

  • "Archives NZ file reference". Archives New Zealand. 2020.
  • "Archives NZ file reference". Archives New Zealand. 2020.
  • "Archives NZ file reference". Archives New Zealand. 2020.


  1. ^ RN circular AFO S 7/44 on Archives NZ RNZN Naval file R21466810

Does anyone have a source for the statement that "the Americans and the British signed the Holden Agreement and BRUSA to develop a Combined Cipher Machine (CCM)"? — Matt Crypto 09:15, 30 November 2005 (UTC)Reply[reply]

Strength vs Enigma[edit]

My understanding is that the key weakness of Enigma was that a letter was never encoded to itself ("T" never became "T"). This allowed the use of cribs (phrases that were guessed to be in the message) to allow a smaller number of possible mappings to be tested. The Typex machine did not have this weakness being able to encode letters to themselves. While there may be other additional security measures over Enigma this is of particular historical significance as it highlights a key difference in the ability to crack the two systems.

I am curious as to why this is not mentioned in the main page in the section on differences? — Preceding unsigned comment added by (talk) 12:56, 7 February 2013 (UTC)Reply[reply]

You are incorrect. Typex was fundamentally a straight copy of the commercial version of the German Enigma. The main complications (to the machine itself) were the addition of two extra non driven rotors, and the printer mechanism(s). A further apparent complication was the presence of an encrypt/decrypt switch, but this only selected which printer printed in 5 character groups and printed 'X's instead of spaces. It had no effect on the actual encryption or decryption itself. Because of the presence of a reflector, the result was a machine that, like enigma, never encrypted any letter as itself. Download the emulator and try it for yourself [1].
The machines were so similar that it was a simple job to remove the extra two rotors and add a plugboard so that Typex machines could be used to decrypt German Enigma messages once the key settings had been found for the day. (talk) 14:44, 1 January 2015 (UTC)Reply[reply]

Some moron added the following entry Typex did not have the major flaw that Enigma did; it was able to produce the same letter that was being pressed. This is wrong. The person is a moron. Typex was an ENIGMA type device, with a reflector. Report FO 850/171 ‘Preparation of telegrams: use of code words: cypher machines and traffic: teleprinter services: en clair messages' contains a memorandum of May 1945, from the Cypher Policy Board to the Foreign Office, with instructions for use of the Typex. It explains that 'When encyphering on the Typex machine, the encyphered version of a letter can never be the letter itself. This sometimes makes it possible to assign with absolute accuracy even a small number of words known or estimated to be in a message to the actual letters of the cypher version ...', and gives procedures for burying addresses’. I hope someone corrects it.

Please do not be offensive. People can be incorrect but it does not make them a moron. (talk) 06:47, 23 April 2020 (UTC)Reply[reply]

How did they actually work?[edit]

The Description section mentions rotors and notches and lubrication and coding speeds, but it does not specify how the machine actually worked. Would someone add that information? John Link (talk) 05:15, 8 November 2014 (UTC)Reply[reply]

External links modified[edit]

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Link error?[edit]

Balata links to wrong target, unless it is meant to be a plant. (talk) 12:57, 5 June 2023 (UTC)Reply[reply]