Talk:Typex

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Contents 1 Weakness of Enigma 2 Reference? 3 Removing for now 4 Replaced book ciphers? 5 Typex usage 6 CCM from the Holden Agreement and BRUSA

[edit] Weakness of Enigma

"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.

[edit] Reference?

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)

[edit] Removing for now

[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)

[edit] Replaced book ciphers?

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)

[edit] Typex usage

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, 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)

[edit] CCM from the Holden Agreement and BRUSA

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)