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Home Page Hebern's machines Hebern 5 rotors v1 Hebern 3 rotors v2 |
IntroductionIn 1924, Friedman won the navy challenge. This challenge aimed to prove the invulnerability of the HCM, Mr Hebern's 5-rotor cipher machine (HCM: Hebern Cipher Machine). Despite this failure, the navy continued to be interested in Hebern's machine and tried to improve it for around ten years until Friedman and his team won a second challenge in 1934 against an improved version of the machine tested by the 1924 challenge. Note: Personally, I call the version tested by the 1934 challenge, HCM 5 rotors version 2. This name is rather arbitrary, given that there were several prototypes (as for any cipher machine) having existed before and even after the 1934 model. Navy experiments after 1924After Friedman won the 1924 challenge, the Navy canceled negotiations with Hebern regarding a large order for 5-rotor cipher machines. On the other hand, the navy not only did not abandon the idea of equipping itself with encryption machines inspired by Hebern's machine, it even hired Hebern as a consultant. Friedman himself, transmitted a proposal for irregular rotor advancement to the Navy which prefigured the Hebern 5-rotors v2 model (see ID A61596 in Web links). Without a doubt, the naval experts agreed with Friedman's conclusion. They also, undoubtedly had access quickly to drafts of Friedman's methods (link). These methods are mainly based on the regular advancement of the rotors. Navy tested several solutions to make the advancement of the rotors more random. It is even testing certain solutions on a machine with three rotors (cf link). In 1928, the Navy purchased four machines from Hebern equipped with five rotors at a price of $750 each and $20 for each rotor. These machines are used not only to test the ideas of cryptologists but are also put into service to provide high-level communications for the Navy. In 1931, the Navy purchased 31 machines to Hebern for $54,480 [1]. These machines incorporate modifications developed by the Navy. These machines are (presumably) put into service as well. In addition, the light board is replaced by a printing system. The two ratchels wheels are grouped on the left. In 1934, to convince themselves that their machine is finally unbreakable, the Navy challenges Friedman again and accepts conditions in favor of the attacker. Indeed, even if it is convinced of the invulnerability of this new machine, the Navy wants to be sure that the machine can resist any enemy. Friedman feels very motivated to win this new challenge and not just for the glory. Indeed, despite his victory in 1924, he was impressed by the degree of safety provided by this type of machine equipped with rotors. From 1926, he planned to create his own cipher machine also equipped with Hebern type rotors. In 1932, under the name M-134, this machine was finally ready and began to be tested. We understand that he does not want a competing model proposed by the navy to destroy his hopes. Although the victory of Friedman's team showed the weaknesses of Hebern's machine, this was not the immediate end of it. It was only withdrawn from service after the Sigaba was built. And again, Hebern's machines continued to be used for land stations until 1942. In fact two machines were captured by the Japanese. Note 1: It seems that the Navy ordered 32 machines and that the last (the 32th) was delivered after the 1934 challenge. The Navy was forced to pay for it. The Army and Navy want to impose their machineIn fact, underlying the story of Mr. Hebern's encryption machines there is the struggle between the Signal Services of the Army and the Navy of the United States Defense Force. Each service has understood that cipher machines are the solution to the needs related to the security of military communications. They enable reliable, secure and rapid encryption. There is no doubt, encryption machines are superior to the use of codes, they represent the future of encryption means. On the other hand, each service wants to impose the machine it has chosen and above all does not want to depend on the other service. The Navy supports Hebern's machines. The Army, through Friedman, wants to impose the machine (M-134) that the latter designed, although it is inspired by Hebern's machine. On October 20, 1935, Rowlet, who significantly improved Friedman's machine in 1935, presented the operation of the machine designed by him and Friedman to the Navy. The Navy pretends to ignore the innovations presented by the Army, but secretly, it bases itself on the ideas presented by Rowlett to create a new machine (the Sigaba). The Navy took the opportunity to modify the machine by adding a gadget, in my opinion not very fundamental. This modification, in my opinion, is more a manifestation of the ego of naval experts than a technical necessity. In the 1930s and 1940s, the Army had budgets very tight unlike Navy which is richer. Therefore, the Navy will be able to ask the Teletype company to mass produce the Sigaba in 1938. The Navy proudly presents "its machine" to the Army at the dawn of the war (February 3, 1940). Rowlett immediately recognized the ideas he had outlined to the Navy a few years before. Although he deplores that the Navy did not keep the Army informed of his actions, he is proud that his ideas triumph. The Sigaba will be used during the 2nd World War as a means of higher level encryption. It will be used by both the Navy and the Army. Finally, more than 10,000 units will be built. The 1934 Navy ChallengeThe conditions of the challenge
The victory of the armyA team of army cryptologists achieved the feat of winning the challenge by deciphering several cryptograms and reconstituting the indicator system. This team consisted of Rowlett, Kullback and Sinkov under the leadership of Friedman. At the end of this challenge, the team wrote a report describing the machine, the challenge and the methods used to win it: "ANALYSIS OF A MECHANICO-ELECTRICAL CRYPTOGRAPH, PART II," (link). Description of rotor advancementThe 1934 machine uses 5 rotors chosen from 6 rotors. On the other hand, encryption must be carried out in REVERSE mode. Remember that for the 1924 machine, you have the choice between DIRECT (encryption) and REVERSE (decryption). Friedman's report indicates that REVERSE mode is safer. But the main difference with the previous machine lies in the advancement of the rotors. Even if the day key specifies as before the order of the rotors used, the message key includes a "DOG SETTING" which specifies the advancement of the rotors which can therefore be different for each message. Here is the progress of the rotors for each possible “DOG SETTING”. We notice that at least two rotors advance for each encrypted letter (the fast rotors). Every 26 letters, another rotor advances (the medium rotor). Finally, every 650 numbered letters, two other rotors move forward (the slow rotors). Rotor movements for all Dog Settings of Hebern Machine Dog setting Fast rotors Medium rotor Slow rotors --------------------------------------------------------- ABV 3 4 5 1 1 2 ABW 3 4 5 2 1 2 ABX 4 5 3 1 2 ABY 3 5 4 1 2 ABZ 3 4 5 1 2 ACW 4 5 2 1 3 ACX 2 4 5 3 1 3 ACY 2 5 4 1 3 ACZ 2 4 5 1 3 ADV 2 3 5 1 1 4 ADW 3 5 2 1 4 ADX 2 5 3 1 4 ADY 2 3 5 4 1 4 ADZ 2 3 5 1 4 AEV 2 3 4 1 1 5 AEW 3 4 2 1 5 AEX 2 4 3 1 5 AEY 2 3 4 1 5 AEZ 2 3 4 5 1 5 BCV 4 5 1 2 3 BCW 1 4 5 2 2 3 BCX 1 4 5 3 2 3 BCY 1 5 4 2 3 BCZ 1 4 5 2 3 BDV 3 5 1 2 4 BDW 1 3 5 2 2 3 4 BDX 1 5 3 2 4 BDY 1 3 5 4 2 4 BDZ 1 3 5 2 4 BEV 3 4 1 2 5 BEW 1 3 4 2 2 5 BEX 1 4 3 1 2 5 BEY 1 3 4 2 5 BEZ 1 3 4 5 2 5 CDV 2 5 1 3 4 CDW 1 5 2 3 4 CDX 1 2 5 3 3 4 CDY 1 2 5 4 3 4 CDZ 1 2 5 3 4 CEV 2 4 1 3 5 CEW 1 4 2 3 5 CEX 1 2 4 3 3 CEY 1 2 4 3 5 CEZ 1 2 4 5 3 5 DEV 2 3 1 4 5 DEW 1 3 2 4 5 DEX 1 2 3 4 5 DEY 1 2 3 4 4 5 DEZ 1 2 3 5 4 5 Some “Dog settings” are not good from a security point of view. So, in the "Dog settings" using the letter V, the left rotor is the only one that advances every 26 letters. So, if we can find the identity and starting position of this rotor, we can remove its effect. References
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