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Visit to National Crytologic Museum: Allies Exhibits

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1. Polish Cryptanalysts

In the 1930s, Polish cryptanalysis worked to find a way to crack the German enigma cipher. Mathematicians Marian Rejewski, Henryk Zigalski, and Jerzy Rozycki, at the Polish Cipher Bureau, were able to create a machine to rapidly find the daily keys for breaking the code.


2. Polish Bomba:

"In September 1938, the Germans changed the way they sent their message keys. All the efforts employed in the previous years became useless. Marian Rejewski designed a machine, which the Polish team called a Bomba. The machine tested the possible rotor settings searching for the ones selected by the Germans. The analysts used indicators within the message itself and a stack of perforated pages designed by Henryk Zygalski to eliminate many rotor settings. The machine and Zyglaski sheets allowed the Polish to find the Enigma's daily rotor setting in only a few hours." Source: Enigma by Wladyslaw Kozaczuk.


3. Turing and the British Bombe

A team lead by Alan Turing built on the Polish concept of the Bomba, but their machine, searched through all 17,576 rotor settings. The British Bombes as conceived by Turing and Welchman and built by Doc Keen arrived at Bletchley Park in August 1940 and eventually over 200 British bombes operated in Britain. They routinely found the rotor settings for the German Air Force and Army but the German Navy Enigma remained virtually unbreakable for another year. The difficulty in cracking the Navy code, stemmed from the fact that the Kriegsmarine had eight rotors (instead of the usual seven) from which to make their daily selection of three.


4. Sugar Camp

In 1942 the U.S. Navy contracted with the National Cash Register Company (NCR) in Dayton, Ohio to build the crytanalytic Bombe. Along with the civilian personnel at NCR, the Navy sent hundreds of men and women to help with the construction.


Sugar Camp, the training facility for NCR sales personnel, became home for hundreds of women in the Navy, known as WAVES (Women Accepted for Volunteer Emergency Service), who lived in the sixty cabins on location.


5-6. The U.S. Navy Bombes

The U.S. Navy Bombes were originally designed by Joseph Desch with the National Cash Register Company. The U.S. Navy Bombes were faster than the British machines and the Navy could build them in large enough quantities to make a difference against the German Enigmas.


The Britain turned over the entire U-boat problem to the U.S. Navy. Approximately 65% of the runs on the Bombes were focused on the German Navy. The Bombes took only twenty minutes to complete a run, testing each of the 456,976 possible rotor settings within one wheel order. Once the daily settings had been retrieved, the Bombes switched over to the three-rotor mode and worked against the German Army and Air Force. They could complete a three-rotor run in only fifty seconds.


7. WAVES and Bombes

By September 1943, the completed Bombes began arriving at the Navy's Nebraska Avenue Communications Annex. WAVES began transferring with the machines, and were trained to operate the Bombes. By the end of World War II, 121 Bombes ran twenty-four hours a day searching for Enigma rotor settings. The machines could search 456,976 settings in twenty minutes.


8. M-9 Bombe Checking Machine

In order to find the Germans' daily rotor selections, several Bombes worked on the same message each testing a different set of wheel orders. Usually two sets of possible rotor settings were found on each run, but only one solution on one Bombe was the correct wheel order and rotor position used by the Germans for that day.


After the Bombe completed a run, a WAVE supervisor checked the printed results on the M-9 Bombe Checking Machine. Each result was checked, to find the correct one. Once found, the M-9 would fill in any missing plugboard positions. Having found the correct wheel order, rotor position, and Steckers, the results were sent back to the library. Here, WAVES and cryptanalysts used an analog machine to decrypt the message. Short messages could be decrypted directly on the M-9.


9-10. The Colossus Machine

In 1943, British engineer Thomas Flowers designed and built the Colossus to combat the German Lorenz cipher, (TUNNY). The world's first electronic computer, the Colossus had data storage and retrieval capabilities, parallel processing, and variable programming ability.


The Colossus machine, had the ability to quickly read Hitler's messages to his generals, which provided the Allies with information on the German preparations for the D-day invasion.


11. Analogs for decrypting the Japanese Red messages

For more than two years, the Army cryptanalysts used handmade analogs to decrypt the Japanese Red messages. These consisted of thin, plastic, sixty-point discs with the sixes and twenties continuously written along the periphery of each disc. In the late 1930s, the Navy Yard model shop constructed an electromechanical RED analog.


12. Purple Analog

The U.S. produced the five Purple analogs used during WWII. The Purple analog had fourteen telephone stepping switches of twenty-five positions each. The model on display is the first one constructed. It was built in the fall of 1940 and decrypted the message revealing Japan's intention to end diplomatic negotiations with the U.S. on December 7, 1941, but did not contain details concerning the attack on Pearl Harbor.

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13. First relay switch for Purple

In early September 1940, the first Purple analog was completed. When being used for an operational dry run, the machine stopped operating just before the end of the first line. It was discovered the master relay contacts had fused together. Frank Rowlett found another relay and Leo Rosen wired a condenser across the contacts of the replacement relay before installing it. Once the new relay was in place the machine performed perfectly and continued to do so until the end of World War II.


The original failed master relay, stayed in Frank Rowlett's possession until he presented it to the National Cryptologic Museum in 1995.


14. Strip Ciphers

Strip ciphers were used during WWII before cipher machines were available, and later as a backup system.


15. Paper Tape Device

This one-time paper tape device was used in conjunction with the SIGTOT cipher system aboard President Roosevelt's airplane, a Douglas C-54 named Sacred Cow.


16. SIGSALY Speech Encryption System 1943-1946

Development of digital technology provided secure voice communications for high-level government officials during WWII. The United States entered World war II without true security capability, but the technical groundwork for a solution was in place at the Bell Telephone Laboratories (BTL). Even with this foundation, the SIGSALY speech encryption system was a huge challenge, for it demanded many unique developments, not simply improvements.


The system was formally put into use on July 15, 1943 in a conference between the Pentagon and London. Twelve terminals were eventually deployed under Army Signal Corps contract and terminals were established in Washington, D.C., London, Paris, North Africa, Hawaii, Guam, Manila, and Australia, among others.


17. Encryption Disk

The SIGGRUV encryption disk contains random pulses and control tones that ensured absolute security for teleconferences between U.S. leaders in Washington and World War II theater headquarters. A duplicate set of disks was located at each end of the communications circuit.


There were two turntables to play the disks: one for transmitting and two for receiving at each terminal.The turntables at each terminal end had to be synchronized to within 0.2 of a millisecond even though separated by up to 10,000 miles and connected by high frequency radio - an incredible accomplishment in 1942.


18. SIGABA: M-135-C (Army), CSP-888 (Navy)

SIGABA was the most secure COMSEC device in use by any nation during WWII and was called the American Big Machine by German cryptanalysts.


Developed from the U.S. Army and Navy attempts to create a cipher machine suitable for high level communications, the resulting machine began what was to be two decades of operational use. There is no know instance of SIGABA generated cipher being broken during World War II.


19. Native American Code talkers

Native Americans used their native languages for combat communications during WWII. The Comanche, Choctaw, and Navajo Tribes were used most frequently as code talkers, but members of other tribes such as Creek, Pawnees, Cherokees, Menominee, Chippewa, and Hopi also were used, all speaking in their own tongue.


Navajo code talkers took part in every assault the U.S. Marines conducted in the Pacific from 1942 to 1945. They served in all six divisions, transmitting messages by radio and telephone in their native language, a code which the Japanese never broke. Code talkers were used on a lesser scale by the Army in Europe and North Africa.


20. Navajo Code Talkers Dictionary

The original group of 29 Navajo recruits created the initial code and developed the dictionary. Each recruit had to memorize the entire vocabulary of over 400 terms. The developers of the original code assigned Navajo words to frequently used military terms that did not exist in the Navajo language.


For words that had to be spelled out, the receiver of a message heard a string of unrelated Navajo words. He translated each Navajo word into English and then used only the first letter of the English equivalents to reconstruct the message.


Information on this page is based on signs and other information at the National Crypologic museum in Annapolis Junction, MD.


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