| Methods and technology |
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| Locations |
| Personnel |
Chief Gwido Langer German Section cryptologists Wiktor Michałowski Chief of Russian Section Jan Graliński Russian Section cryptologist Piotr Smoleński |
| The Enigma cipher machine |
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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. [1]
The Polish Cipher Bureau used the theory of permutations to start breaking the Enigma cipher in late 1932. The Bureau recognized that the Enigma machine's doubled-key (see Grill (cryptology)) permutations formed cycles, and those cycles could be used to break the cipher. With German cipher keys provided by a French spy, the Bureau was able to reverse engineer the Enigma and start reading German messages. At the time, the Germans were using only 6 steckers, and the Polish grill method was feasible. On 1 August 1936, the Germans started using 8 steckers, and that change made the grill method less feasible. The Bureau needed an improved method to break the German cipher.
Although the steckers would change which letters were in a doubled-key's cycle, the steckers would not change the number of cycles or the length of those cycles. Steckers could be ignored. Ignoring the mid-key turnovers, the Enigma machine had only 263 distinct settings of the three rotors, and the three rotors could only be arranged in the machine 3!=6 ways. That meant there were only 105456 likely doubled-key permutations. The Bureau set about determining and cataloging the characteristic of each of those likely permutations. Each letter of the key could be one of partition number 13 = 101 possible values, and the 3 letters of the key meant there were 1030301 possible keys. On average, a key would find one setting of the rotors, but it might find several possible settings.
The Polish cryptanalyst could then collect enough traffic to determine all the cycles in a daily key. That usually took about 60 messages. The result might be:
He would use the lengths of the cycles (132;102-32;102-22-12) to look up the wheel order (II I III) and starting rotor positions in the card catalog. He would then use an Enigma to compute the un-steckered cycles:
By comparing the steckered cycles from the German traffic and the un-steckered cycles, the cryptanalyst can determine the steckers. In the example, the CF permutation has (e)(z) and (e)(w). That requires that e is unsteckered and a W-Z stecker. The cycles can then be aligned on e and W-Z to determine other steckered and un-steckered letters.
(pjxroquctwzsy)(kvgledmanhfib)/(kxtcoigweh)...(sjxroqtcuzwpy)(kngledamvhifb)/(kxucofgzeh)...(!_____!_!**!_)(_!__=_!!!_!!_)/(__!__!_*=_)...Where = is a known un-steckered letter, * is a known steckered letter, and ! is a newly discovered stecker. Repetition produces the steckers A-M, F-I, N-V, P-S, T-U, W-Z.
Preparation of the card catalog, using the cyclometer that Rejewski had invented about 1934 or 1935, was a laborious task that took over a year's time. But once the catalog was complete, obtaining Enigma daily keys was a matter of some fifteen minutes. [2] [3]
When the Germans changed the Enigma machine's "reflector," or "reversing drum," on 1 November 1937, the Cipher Bureau was forced to start over again with a new card catalog: "a task," writes Rejewski, "which consumed, on account of our greater experience, probably somewhat less than a year's time." [2]
On 15 September 1938 the Germans completely changed the procedure for enciphering message keys, rendering the card-catalog method useless. This spurred the invention of Rejewski's cryptologic bomb and Henryk Zygalski's "perforated sheets." [4]
Jerzy Witold Różycki was a Polish mathematician and cryptologist who worked at breaking German Enigma-machine ciphers before and during World War II.
Henryk Zygalski was a Polish mathematician and cryptologist who worked at breaking German Enigma ciphers before and during World War II.
The known-plaintext attack (KPA) is an attack model for cryptanalysis where the attacker has access to both the plaintext, and its encrypted version (ciphertext). These can be used to reveal further secret information such as secret keys and code books. The term "crib" originated at Bletchley Park, the British World War II decryption operation, where it was defined as:
A plain language passage of any length, usually obtained by solving one or more cipher or code messages, and occurring or believed likely to occur in a different cipher or code message, which it may provide a means of solving.
The Cipher Bureau, in Polish: Biuro Szyfrów ([ˈbʲurɔ ˈʂɨfruf], was the interwar Polish General Staff's Second Department's unit charged with SIGINT and both cryptography and cryptanalysis.
The bomba, or bomba kryptologiczna, was a special-purpose machine designed around October 1938 by Polish Cipher Bureau cryptologist Marian Rejewski to break German Enigma-machine ciphers.
Cryptanalysis of the Enigma ciphering system enabled the western Allies in World War II to read substantial amounts of 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 teleprinter transmissions, was given the codename Ultra.
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.
Antoni Palluth was a founder of the AVA Radio Company. The company built communications equipment for the Polish military; the work included not only radios but also cryptographic equipment. Palluth was involved with the German section (BS-4) of the Polish General Staff's interbellum Cipher Bureau. He helped teach courses on cryptanalysis, and he was involved with building equipment to break the German Enigma machine.
Cadix was a World War II clandestine intelligence center at Uzès, in southern France, from September 1940 to 9 November 1942. During this period southern France was under the control of Vichy France and not occupied by Nazi Germany. At Cadix, the predominantly Polish team of cryptanalysts who had previously worked at PC Bruno was reassembled, and worked against German and other Axis ciphers, including the German Enigma machine cipher. Cadix shut down when Germany occupied southern France.
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. The original machines are believed to have been destroyed shortly before the German invasion of Poland that launched the Second World War, to prevent the Germans learning that their cipher had been broken.
The Lacida, also called LCD, was a Polish rotor cipher machine. It was designed and produced before World War II by Poland's Cipher Bureau for prospective wartime use by Polish military higher commands.
Gustave Bertrand (1896–1976) was a French military intelligence officer who made a vital contribution to the decryption, by Poland's Cipher Bureau, of German Enigma ciphers, beginning in December 1932. This achievement would in turn lead to Britain's celebrated World War II Ultra operation.
In cryptography, the clock was a method devised by Polish mathematician-cryptologist Jerzy Różycki, at the Polish General Staff's Cipher Bureau, to facilitate decrypting German Enigma ciphers. The method determined the rightmost rotor in the German Enigma by exploiting the different turnover positions. For the Poles, learning the rightmost rotor reduced the rotor-order search space by a factor of 3. The British improved the method, and it allowed them to use their limited number of bombes more effectively.
The grill method, in cryptology, was a method used chiefly early on, before the advent of the cyclometer, by the mathematician-cryptologists of the Polish Cipher Bureau in decrypting German Enigma machine ciphers. The Enigma rotor cipher machine changes plaintext characters into cipher text using a different permutation for each character, and so implements a polyalphabetic substitution cipher.
Marian Adam Rejewski was a Polish mathematician and cryptologist who in late 1932 reconstructed the sight-unseen German military Enigma cipher machine, aided by limited documents obtained by French military intelligence. Over the next nearly seven years, Rejewski and fellow mathematician-cryptologists Jerzy Różycki and Henryk Zygalski developed and used techniques and equipment to decrypt the German machine ciphers, even as the Germans introduced modifications to their equipment and encryption procedures. Five weeks before the outbreak of World War II the Poles, at a conference in Warsaw, shared their achievements with the French and British, thus enabling Britain to begin reading German Enigma-encrypted messages, seven years after Rejewski's original reconstruction of the machine. The intelligence that was gained by the British from Enigma decrypts formed part of what was code-named Ultra and contributed—perhaps decisively—to the defeat of Germany.
A Polish Enigma "double" was a machine produced by the Polish Cipher Bureau that replicated the German Enigma rotor cipher machine. The Enigma double was one result of Marian Rejewski's remarkable achievement of determining the wiring of the Enigma's rotors and reflectors.
Ludomir Danilewicz was a Polish engineer and, for some ten years before the outbreak of World War II, one of the four directors of the AVA Radio Company in Warsaw, Poland. AVA designed and built radio equipment for the Polish General Staff's Cipher Bureau, which was responsible for the radio communications of the General Staff's Oddział II.
Leonard Stanisław Danilewicz was a Polish engineer and, for some ten years before the outbreak of World War II, one of the four directors of the AVA Radio Company in Warsaw, Poland.
The AVA Radio Company was a Polish electronics firm founded in 1929 in Warsaw, Poland. AVA designed and built radio equipment for the Polish General Staff's Cipher Bureau, which was responsible for the radio communications of the General Staff's Oddział II.
Edward Fokczyński was one of the four directors of the AVA Radio Company, an electronics firm established in Warsaw, Poland, in 1929. AVA produced radio equipment for the Polish General Staff's Cipher Bureau, which was responsible for the radio communications of the General Staff's Intelligence Section.