US Navy Cryptanalytic Bombe

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US Navy Cryptanalytic Bombe

Image by brewbooks
By 1943, Bombes began arriving at the Navy’s Nebraska Avenue Communications Annex at a rate of four per week. The WAVES in Dayton began transferring with the machines and were trained to operate the Bombes. By the end of the war, 121 Bobles ran 24 hours per day, searching for Enigma rotor settings. THe machines could search 456,976 setting in 20 minutes.

THe US Navy Bombes were faster than the British machines and the Navy could build them in large enough quantity to make a difference againt the ENIGMAs. Britain turned over the U-boat problem to the US Navy and even requested the US to build an additional fifty machines, of which only 26 were needed before production stopped. The original ninty six were sufficent to handle the U-boat messages, but the ground war was growing and Britain wanted assistance against German Army and Air Force Engma messages. Approximately 65% of the runs on the Bombes were German Navy. Once the daily settings had been retrieved, the Bombes switched over to a three rotor mode and worked against the German army and Air Force. They cound complete a three-rotor run in only fifty seconds.
Source: National Cryptologic Museum

Comment on the above
The four rotor system had 26^4 or 456,976 settings whilst the theree rotor system had 26^3 or 17,756 settings. It looks like the problem scale in a linear way as it took 50 seconds to check 17,756 setting (~350 per second) while the four rotor solution in 20 minutes is ~ 380 settings per second.

also think the designer Joseph Desch sounds like a remarkable engineer that I never heard of before.

Bombe on Wikipedia
Once the British had given the Americans the details about the bombe and its use, the US had the National Cash Register Company manufacture a great many additional bombes, which the US then used to assist in the code-breaking. These ran much faster than the British version, so fast that unlike the British model, which would freeze immediately (and ring a bell) when a possible solution was detected, the NCR model, upon detecting a possible solution, had to "remember" that setting and then reverse its rotors to back up to it (meanwhile the bell rang).

Source of following material : National Cryptologic Museum
Switch Banks tell the Bombe what plain to cipher letters to search for. Using menus sent to the Bombe deck by cryptanalysts, WAVES set each dial using special wrenches. 00 equates to the letter A and 25 to the letter Z. The dials work together in groups of two. One dial is set to the plain test letter and the other to its corresponding cipher letter as determined by cryptanalysts. There are sixteen sets of switch banks, however, only fourteen were required to complete a run. As the machine worked through the rotor settings, a correct hit was possible if the electrical path in all fourteen switch banks corresponded to each of their assigned plaintext/cipher combinations.

Wheel Banks represent the four rotors used on the German U-boat Enigma. Each column interconnects the four rotors, or commutators, in that column. The top commutator represented the fourth, or slowest, rotor on the Enigma, while the bottom wheel represented the rightmost, or fastest, rotor. The WAVES set the rotors according to the menu developed by the cryptanalysts. The first were set to 00, and each set after that corresponded to the plain/cipher link with the crib (the assumed plain test corresponding to the cipher text.) Usually this meant that each wheel bank stepped up one place from the one on its left. When the machine ran, each bottom rotor stepped forward, and the machine electrically checked to see if the assigned conditions were met. If not, as was usually the case, each bottom wheels moved one more place forward. However, the bottom commutator moved at 850 rpm, so it only took twenty minutes to complete a run of all 456,976 positions.
i09_0214 125

US Navy Cryptanalytic Bombe

Image by brewbooks
By 1943, Bombes began arriving at the Navy’s Nebraska Avenue Communications Annex at a rate of four per week. The WAVES in Dayton began transferring with the machines and were trained to operate the Bombes. By the end of the war, 121 Bobles ran 24 hours per day, searching for Enigma rotor settings. THe machines could search 456,976 setting in 20 minutes.

THe US Navy Bombes were faster than the British machines and the Navy could build them in large enough quantity to make a difference againt the ENIGMAs. Britain turned over the U-boat problem to the US Navy and even requested the US to build an additional fifty machines, of which only 26 were needed before production stopped. The original ninty six were sufficent to handle the U-boat messages, but the ground war was growing and Britain wanted assistance against German Army and Air Force Engma messages. Approximately 65% of the runs on the Bombes were German Navy. Once the daily settings had been retrieved, the Bombes switched over to a three rotor mode and worked against the German army and Air Force. They cound complete a three-rotor run in only fifty seconds.
Source: National Cryptologic Museum

Comment on the above
The four rotor system had 26^4 or 456,976 settings whilst the theree rotor system had 26^3 or 17,756 settings. It looks like the problem scale in a linear way as it took 50 seconds to check 17,756 setting (~350 per second) while the four rotor solution in 20 minutes is ~ 380 settings per second.

also think the designer Joseph Desch sounds like a remarkable engineer that I never heard of before.

Bombe on Wikipedia
Once the British had given the Americans the details about the bombe and its use, the US had the National Cash Register Company manufacture a great many additional bombes, which the US then used to assist in the code-breaking. These ran much faster than the British version, so fast that unlike the British model, which would freeze immediately (and ring a bell) when a possible solution was detected, the NCR model, upon detecting a possible solution, had to "remember" that setting and then reverse its rotors to back up to it (meanwhile the bell rang).

i09_0214 109z

Ketos ring

Image by Official U.S. Air Force
Staff Sgt. Dustin Harris washes a Ketos ring with a magnetic particle solution Nov. 7, 2013, at MacDill Air Force Base, Fla. The Ketos ring is inspected weekly to ensure the machine is working properly. Harris is a 6th Maintenance Squadron nondestructive inspection technician. (U.S. Air Force photo/Brandon Shapiro)

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