Cyclometer
Encyclopedia
The cyclometer was a cryptologic device designed, "probably in 1934 or 1935," by Marian Rejewski
of the Polish Cipher Bureau's German section (BS-4) to facilitate decryption of German Enigma
ciphertext
.
in the "characteristics" for all 17,576 positions of the rotors for a given sequence of rotors. Since there were six such possible sequences, the resulting "catalog of characteristics," or "card catalog
," comprised a total of (6) (17,576) = 105,456 entries.
The utility of the card catalog
, writes Rejewski, was independent of the number of plug connections being used by the Germans on their Enigma machines (and of the reconstruction of message keys). Preparation of the catalog "was laborious and took over a year, but when it was ready... daily keys [could be obtained] within about fifteen minutes."
On November 1, 1937, however, the Germans changed the "reversing drum," or "reflector
." This forced the Cipher Bureau to start over again and produce a new card catalog, "a task," writes Rejewski, "which consumed, on account of our greater experience, probably somewhat less than a year's time."
But then, on September 15, 1938, the Germans changed entirely the procedure for enciphering message keys, and as a result the card-catalog
method became completely useless.
This spurred the invention of Rejewski
's cryptologic bomb
and Zygalski
's perforated sheets
.
Marian Rejewski
Marian Adam Rejewski was a Polish mathematician and cryptologist who in 1932 solved the plugboard-equipped Enigma machine, the main cipher device used by Germany...
of the Polish Cipher Bureau's German section (BS-4) to facilitate decryption of German Enigma
Enigma machine
An Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...
ciphertext
Ciphertext
In cryptography, ciphertext is the result of encryption performed on plaintext using an algorithm, called a cipher. Ciphertext is also known as encrypted or encoded information because it contains a form of the original plaintext that is unreadable by a human or computer without the proper cipher...
.
History
The cyclometer was used to prepare a catalog of the length and number of cyclesCycle graph (algebra)
In group theory, a sub-field of abstract algebra, a group cycle graph illustrates the various cycles of a group and is particularly useful in visualizing the structure of small finite groups...
in the "characteristics" for all 17,576 positions of the rotors for a given sequence of rotors. Since there were six such possible sequences, the resulting "catalog of characteristics," or "card catalog
Card catalog (cryptology)
The card catalog, or "catalog of characteristics," in cryptography, was a system designed by Polish Cipher Bureau mathematician-cryptologist Marian Rejewski, and first completed about 1935 or 1936, to facilitate decrypting German Enigma ciphers.-History:...
," comprised a total of (6) (17,576) = 105,456 entries.
The utility of the card catalog
Card catalog (cryptology)
The card catalog, or "catalog of characteristics," in cryptography, was a system designed by Polish Cipher Bureau mathematician-cryptologist Marian Rejewski, and first completed about 1935 or 1936, to facilitate decrypting German Enigma ciphers.-History:...
, writes Rejewski, was independent of the number of plug connections being used by the Germans on their Enigma machines (and of the reconstruction of message keys). Preparation of the catalog "was laborious and took over a year, but when it was ready... daily keys [could be obtained] within about fifteen minutes."
On November 1, 1937, however, the Germans changed the "reversing drum," or "reflector
Reflector (cipher machine)
A reflector, in cryptology, is a component of some rotor cipher machines, such as the Enigma machine, that sends electrical impulses that have reached it from the machine's rotors, back in reverse order through those rotors.- Other names :...
." This forced the Cipher Bureau to start over again and produce a new card catalog, "a task," writes Rejewski, "which consumed, on account of our greater experience, probably somewhat less than a year's time."
But then, on September 15, 1938, the Germans changed entirely the procedure for enciphering message keys, and as a result the card-catalog
Card catalog (cryptology)
The card catalog, or "catalog of characteristics," in cryptography, was a system designed by Polish Cipher Bureau mathematician-cryptologist Marian Rejewski, and first completed about 1935 or 1936, to facilitate decrypting German Enigma ciphers.-History:...
method became completely useless.
This spurred the invention of Rejewski
Marian Rejewski
Marian Adam Rejewski was a Polish mathematician and cryptologist who in 1932 solved the plugboard-equipped Enigma machine, the main cipher device used by Germany...
's cryptologic bomb
Bomba (cryptography)
The bomba, or bomba kryptologiczna was a special-purpose machine designed about October 1938 by Polish Cipher Bureau cryptologist Marian Rejewski to break German Enigma-machine ciphers....
and Zygalski
Henryk Zygalski
Henryk Zygalski was a Polish mathematician and cryptologist who worked at breaking German Enigma ciphers before and during World War II.-Life:...
's perforated sheets
Perforated sheets
The method of Zygalski sheets was a cryptologic technique used by the Polish Cipher Bureau before and during World War II, and during the war also by British cryptologists at Bletchley Park, to decrypt messages enciphered on German Enigma machines....
.
See also
- Cryptologic bombBomba (cryptography)The bomba, or bomba kryptologiczna was a special-purpose machine designed about October 1938 by Polish Cipher Bureau cryptologist Marian Rejewski to break German Enigma-machine ciphers....
: a machine designed about October 1938 by Marian RejewskiMarian RejewskiMarian Adam Rejewski was a Polish mathematician and cryptologist who in 1932 solved the plugboard-equipped Enigma machine, the main cipher device used by Germany...
to facilitate the retrieval of Enigma keys. - BombeBombeThe bombe was an electromechanical device used by British cryptologists to help decipher German Enigma-machine-encrypted signals during World War II...
: a machine, inspired by Rejewski's "(cryptologic) bomb," that was used by British and American cryptologists during World War II. - Cryptanalysis of the EnigmaCryptanalysis of the EnigmaCryptanalysis of the Enigma enabled the western Allies in World War II to read substantial amounts of secret Morse-coded radio communications of the Axis powers that had been enciphered using Enigma machines. This yielded military intelligence which, along with that from other decrypted Axis radio...
and Enigma machineEnigma machineAn Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...
. - Zygalski sheetsPerforated sheetsThe method of Zygalski sheets was a cryptologic technique used by the Polish Cipher Bureau before and during World War II, and during the war also by British cryptologists at Bletchley Park, to decrypt messages enciphered on German Enigma machines....
: invented about October 1938 by Henryk ZygalskiHenryk ZygalskiHenryk Zygalski was a Polish mathematician and cryptologist who worked at breaking German Enigma ciphers before and during World War II.-Life:...
and called "perforated sheets" by the Poles, they made possible the recovery of the Enigma's entire cipher key.
External links
- "Polish Enigma Double"
- About the Enigma (National Security Agency)
- http://www.armyradio.com/publish/Articles/The_Enigma_Code_Breach/The_Enigma_Code_Breach.htm"The Enigma Code Breach" by Jan BuryJan BuryJan Bury is a Polish politician. He was elected to Sejm on September 25, 2005 getting 12050 votes in 23 Rzeszów district, candidating from Polish People's Party list....
] - The „Enigma” and the Intelligence
- "Codebreaking and Secret Weapons in World War II" By Bill Momsen
- A Brief History of Computing Technology, 1930 to 1939