US Navy Cryptanalytic Bombe
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
US Navy Cryptanalytic Bombe
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