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39-787: The British had shown their main cipher machine — Typex — to the US on their entry into the war, but the Americans were reluctant to share their machine, the ECM Mark II . 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 "Combined Cipher Machine" was approved in October 1942, and production began two months later. The requisite adapters, designed by Don Seiler, were all manufactured in

78-527: A cam that caused the rotor to stop in the proper position during the zeroize process. SIGABA's rotors were all housed in a removable frame held in place by four thumb screws. This allowed the most sensitive elements of the machine to be stored in more secure safes and to be quickly thrown overboard or otherwise destroyed if capture was threatened. It also allowed a machine to quickly switch between networks that used different rotor orders. Messages had two 5- character indicators, an exterior indicator that specified

117-480: A complex, pseudorandom fashion. This meant that attacks which could break other rotor machines with simpler stepping (for example, Enigma) were made much more complex. Even with the plaintext in hand, there were so many potential inputs to the encryption that it was difficult to work out the settings. On the downside, the SIGABA was also large, heavy, expensive, difficult to operate, mechanically complex, and fragile. It

156-525: A dangerously short period of 338; a three-rotor Enigma machine had a period of 16,900. In addition, the rotor wiring could be recovered from a 1,000-group message that had been sent using the machine. In 1952, a later version of CCM, "Ajax", was also found to have security problems. SIGABA In the history of cryptography , the ECM Mark II was a cipher machine used by the United States for message encryption from World War II until

195-411: A four character match should be accepted. The manual also gave suggestions on how to generate random strings for creating indicators. These included using playing cards and poker chips, to selecting characters from cipher texts and using the SIGABA itself as a random character generator. Although the SIGABA was extremely secure, the US continued to upgrade its capability throughout the war, for fear of

234-628: A number of features to make the machine easier to build, resulting in the Electric Code Machine Mark II (or ECM Mark II ), which the navy then produced as the CSP-889 (or 888). Oddly, the Army was unaware of either the changes or the mass production of the system, but were "let in" on the secret in early 1940. In 1941 the Army and Navy joined in a joint cryptographic system, based on the machine. The Army then started using it as

273-583: Is publicly known. It was clear to US cryptographers well before World War II that the single-stepping mechanical motion of rotor machines (e.g. the Hebern machine ) could be exploited by attackers. In the case of the famous Enigma machine , these attacks were supposed to be upset by moving the rotors to random locations at the start of each new message. This, however, proved not to be secure enough, and German Enigma messages were frequently broken by cryptanalysis during World War II. William Friedman , director of

312-689: The CSP 1700 ). 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. The CCM programme cost US$ 6 million. 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). TypeX Mark 23

351-819: The Central Intelligence Agency (CIA) in 1952 and worked there until 1958. At that time he returned to NSA as a Special Assistant to the Director. In 1965 Rowlett became commandant of the National Cryptologic School . In 1965, Rowlett was awarded the President's Award for Distinguished Federal Civilian Service . He retired from federal service in 1966. In 1965 he was awarded the National Security Medal by President Lyndon B. Johnson for his work on breaking

390-594: The M-134 Converter , and its message settings included the position of the tape and the settings of a plugboard that indicated which line of holes on the tape controlled which rotors. However, there were problems using fragile paper tapes under field conditions. Friedman's associate, Frank Rowlett , then came up with a different way to advance the rotors, using another set of rotors. In Rowlett's design, each rotor must be constructed such that between one and four output signals were generated, advancing one or more of

429-501: The SIGABA . Just over 10,000 machines were built. On 26 June 1942, the Army and Navy agreed not to allow SIGABA machines to be placed in foreign territory except where armed American personnel were able to protect the machine. The SIGABA would be made available to another Allied country only if personnel of that country were denied direct access to the machine or its operation by an American liaison officer who would operate it. SIGABA

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468-739: The Typex . The common machine was known as the Combined Cipher Machine (CCM), and was used from November 1943. Because of the high cost of production, only 631 CCMs were made. The third way was the most common and most cost-effective. It was the "X" Adapter manufactured by the Teletype Corporation in Chicago. A total of 4,500 of these adapters were installed at depot-level maintenance facilities. Frank Rowlett Frank Byron Rowlett (May 2, 1908 – June 29, 1998)

507-460: The US Army 's Signals Intelligence Service , devised a system to correct for this attack by truly randomizing the motion of the rotors. His modification consisted of a paper tape reader from a teletype machine attached to a small device with metal "feelers" positioned to pass electricity through the holes. When a letter was pressed on the keyboard the signal would be sent through the rotors as it

546-520: The 1930s, after a lengthy period of training, Rowlett and his colleagues compiled codes and ciphers for use by the U.S. Army and began solving a number of foreign, notably Japanese , systems. In the mid-1930s, they solved the first Japanese machine for encipherment of diplomatic communications, known to the Americans as RED . In 1939–40, Rowlett led the SIS effort that solved a more sophisticated Japanese diplomatic machine cipher, codenamed PURPLE by

585-519: The 1950s. The machine was also known as the SIGABA or Converter M-134 by the Army, or CSP-888/889 by the Navy, and a modified Navy version was termed the CSP-2900 . Like many machines of the era it used an electromechanical system of rotors to encipher messages, but with a number of security improvements over previous designs. No successful cryptanalysis of the machine during its service lifetime

624-567: The Axis cryptanalytic ability to break SIGABA's code. When the German's ENIGMA messages and Japan's Type B Cipher Machine were broken, the messages were closely scrutinized for signs that Axis forces were able to read the US cryptography codes. Axis prisoners of war (POWs) were also interrogated with the goal of finding evidence that US cryptography had been broken. However, neither the Germans nor

663-764: The Germans admitted that their progress in breaking US communications was unsatisfactory. The Japanese also admitted in their own communications that they had made no real progress against the American cipher system. In September 1944, when the Allies were advancing steadily on the Western front, the war diary of the German Signal Intelligence Group recorded: "U.S. 5-letter traffic: Work discontinued as unprofitable at this time". SIGABA systems were closely guarded at all times, with separate safes for

702-730: The Japanese were making any progress in breaking the SIGABA code. A decrypted JN-A-20 message, dated 24 January 1942, sent from the naval attaché in Berlin to vice chief of Japanese Naval General Staff in Tokyo stated that "joint Jap[anese]-German cryptanalytical efforts" to be "highly satisfactory", since the "German[s] have exhibited commendable ingenuity and recently experienced some success on English Navy systems", but are "encountering difficulty in establishing successful techniques of attack on 'enemy' code setup". In another decrypted JN-A-20 message,

741-586: The Pacific Theater. In other theatres, less secure, but smaller, lighter, and sturdier machines were used, such as the M-209 . SIGABA, impressive as it was, was overkill for tactical communications. This said, new speculative evidence emerged more recently that the M-209 code was broken by German cryptanalysts during World War II. Because SIGABA did not have a reflector, a 26+ pole switch was needed to change

780-415: The U.S. Once, when asked what his greatest contribution to that effort had been, Rowlett said, "I was the one who believed it could be done." Rowlett supervised cryptanalyst Virginia Dare Aderholdt , who decrypted the Japanese surrender message, August 14, 1945. Rowlett also played a crucial role in protecting American communications during World War II , making fundamental and innovative contributions to

819-630: The US, as Britain did not have sufficient manufacturing resources at the time. 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 to convert the ECM into the CCM was denoted the ASAM 5 by the US Army (in 1949) and CSP 1600 by the US Navy (the Navy referred to the entire ECM machine with CCM adapter as

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858-581: The combination of machines as the M-134-C. In 1935 they showed their work to Joseph Wenger , a cryptographer in the OP-20-G section of the U.S. Navy . He found little interest for it in the Navy until early 1937, when he showed it to Commander Laurance Safford , Friedman's counterpart in the Office of Naval Intelligence . He immediately saw the potential of the machine, and he and Commander Seiler then added

897-412: The design of the SIGABA cipher machine . Its security was an important factor in saving American lives in combat. In 1964, Congress awarded Rowlett US$ 100,000, equivalent to $ 980,000 in 2023, as partial compensation for his classified cryptologic inventions. In addition to having highly developed cryptanalytic skills, Rowlett was a good manager, and he rose quickly within the organization. In 1943–45 he

936-442: The machine and having the operator select a random 5-character string for each new message. This was then encrypted to produce the interior indicator. Army key lists included an initial setting for the rotors that was used to encrypt the random string. The Navy operators used the keyboard to increment the code rotors until they matched the random character string. The alphabet rotor would move during this process and their final position

975-570: The need for a cipher system that could be used by all Allied forces. This functionality was achieved in three different ways. Firstly, the ECM Adapter (CSP 1000), which could be retrofitted on Allied cipher machines, was produced at the Washington Naval Yard ECM Repair Shop. A total of 3,500 adapters were produced. The second method was to adapt the SIGABA for interoperation with a modified British machine,

1014-489: The rotors (rotors normally have one output for every input). There was little money for encryption development in the US before the war, so Friedman and Rowlett built a series of "add on" devices called the SIGGOO (or M-229) that were used with the existing M-134s in place of the paper tape reader. These were external boxes containing a three rotor setup in which five of the inputs were live, as if someone had pressed five keys at

1053-418: The rotors and to zeroize the machine. The O position turned the machine off. The P setting was used to print the indicators and date/time groups on the output tape. It was the only mode that printed numbers. No printing took place in the R setting, but digit keys were active to increment rotors. During encryption, the Z key was connected to the X key and the space bar produced a Z input to the alphabet maze. A Z

1092-426: The same time on an Enigma, and the outputs were "gathered up" into five groups as well — that is all the letters from A to E would be wired together for instance. That way the five signals on the input side would be randomized through the rotors, and come out the far side with power in one of five lines. Now the movement of the rotors could be controlled with a day code, and the paper tape was eliminated. They referred to

1131-401: The signal paths through the alphabet maze between the encryption and decryption modes. The long “controller” switch was mounted vertically, with its knob on the top of the housing. See image. It had five positions, O, P, R, E and D. Besides encrypt (E) and decrypt (D), it had a plain text position (P) that printed whatever was typed on the output tape, and a reset position (R) that was used to set

1170-529: The system base and the code-wheel assembly, but there was one incident where a unit was lost for a time. On February 3, 1945, a truck carrying a SIGABA system in three safes was stolen while its guards were visiting a brothel in recently liberated Colmar, France . General Eisenhower ordered an extensive search, which finally discovered the safes six weeks later in a nearby river. The need for cooperation among US, British, and Canadian forces in carrying out joint military operations against Axis forces gave rise to

1209-446: The system being used and the security classification and an interior indicator that determined the initial settings of the code and alphabet rotors. The key list included separate index rotor settings for each security classification. This prevented lower classification messages from being used as cribs to attack higher classification messages. The Navy and Army had different procedures for the interior indicator. Both started by zeroizing

Combined Cipher Machine - Misplaced Pages Continue

1248-558: Was a later model of the Typex cipher machine family that was adapted for use with the Combined Cipher Machine. While Allied codebreakers had much success reading the equivalent German machine, the Lorenz cipher , their German counterparts, although performing some initial analysis, had no success with the CCM. However, there were security problems with the CCM. It was discovered that certain rotor combinations produced

1287-638: Was an American cryptologist . Rowlett was born in Rose Hill, Lee County, Virginia and attended Emory & Henry College in Emory, Virginia . In 1929 he received a bachelor's degree in mathematics and chemistry. He was hired by William Friedman as a "junior cryptanalyst" for the Signals Intelligence Service (SIS) on April Fools' Day 1930; shortly after, he was followed into SIS by Abraham Sinkov and Solomon Kullback . During

1326-799: Was chief of the General Cryptanalytic Branch, and in 1945–1947 chief of the Intelligence Division. From 1949 to 1952, he was technical director in the Office of Operations of the Armed Forces Security Agency , predecessor to the National Security Agency (NSA). Rowlett differed with General Ralph J. Canine , the first director of NSA, over personnel movements, including his own. Acting on his differences, he transferred to

1365-482: Was in the Enigma, producing an encrypted version. In addition, the current would also flow through the paper tape attachment, and any holes in the tape at its current location would cause the corresponding rotor to turn, and then advance the paper tape one position. In comparison, the Enigma rotated its rotors one position with each key press, a much less random movement. The resulting design went into limited production as

1404-464: Was nowhere near as practical a device as the Enigma, which was smaller and lighter than the radios with which it was used. It found widespread use in the radio rooms of US Navy ships, but as a result of these practical problems the SIGABA simply couldn't be used in the field. In most theatres other systems were used instead, especially for tactical communications. One of the most famous was the use of Navajo code talkers for tactical field communications in

1443-407: Was printed as a space on decryption. The reader was expected to understand that a word like “xebra” in a decrypted message was actually “zebra.” The printer automatically added a space between each group of five characters during encryption. The SIGABA was zeroized when all the index rotors read zero in their low order digit and all the alphabet and code rotors were set to the letter O. Each rotor had

1482-442: Was similar to the Enigma in basic theory, in that it used a series of rotors to encipher every character of the plaintext into a different character of ciphertext. Unlike Enigma's three rotors however, the SIGABA included fifteen, and did not use a reflecting rotor. The SIGABA had three banks of five rotors each; the action of two of the banks controlled the stepping of the third. The SIGABA advanced one or more of its main rotors in

1521-444: Was the internal indicator. In case of joint operations, the Army procedures were followed. The key lists included a “26-30” check string. After the rotors were reordered according to the current key, the operator would zeroize the machine, encrypt 25 characters and then encrypt “AAAAA”. The ciphertext resulting from the five A's had to match the check string. The manual warned that typographical errors were possible in key lists and that

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