The usage “crib” was adapted from a slang term referring to cheating—thus, “I cribbed my answer from your test paper.” A “crib” originally was a literal or interlinear translation of a foreign-language text — usually a Latin or Greek text — that students might be assigned to translate from the original language.

The idea behind a crib is that cryptologists were looking at incomprehensible ciphertext, but if they had a clue about some word or phrase that might be expected to be in the ciphertext, they would have a “wedge”—a test to break into it. If their otherwise random attacks on the cipher managed to sometimes produce those words or (preferably) phrases, they would know they might be on the right track. When those words or phrases appeared, they would feed the settings they had used to reveal them back into the whole encrypted message, to good effect.

In the case of Enigma, the German High Command was very meticulous about the overall security of the Enigma system, but nonetheless understood the possible problem of cribs. The day-to-day trench operators, on the other hand, were less careful.

Enigma messages would often be broadcast, every day, with the same stereotyped introduction. For example, an officer in the Africa Corps helped greatly by constantly sending: “Nothing to report.” Other operators too would send standard salutations or introductions. Standardized weather reports were also particularly helpful.

When cribs were lacking, Bletchley Park would sometimes ask the Royal Air Force to “seed” a particular area in the North Sea with mines (a process that came to be known as gardening, by obvious reference). The Enigma messages that were shortly sent out would most likely contain the name of the area, or the harbour threatened by the mines.

When a captured German revealed under interrogation that Enigma operators had been instructed to encode numbers by spelling them out, Alan Turing reviewed decrypted messages, and determined that the number “eins” (“1”) appeared in 90% of messages. He automated the crib process, creating the Eins Catalogue, which assumed that “eins” was encoded at all positions in the plaintext. The catalogue included every possible position of the various rotors, starting positions, and keysettings of the Enigma.


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B.R. Ambedkar

“It is disgraceful to live at the cost of one’s self-respect.  Self-respect is the most vital factor in life.  Without it, man is a cipher.  To live worthily with self-respect, one has to overcome difficulties.  It is out of hard and ceaseless struggle alone that one derives strength, confidence and recognition.”

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Walter Wriston

“It is a maxim of cryptology that what one man can devise, another can unravel. This principle keeps armies of tax lawyers and accountants employed, but adds nothing to our national productivity.”

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David Kahn

“Few false ideas have more firmly gripped the minds of so many intelligent men than the one that, if they just tried, they could invent a cipher that no one could break.”

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Alan Turing

“There is a remarkably close parallel between the problems of the physicist and those of the cryptographer. The system on which a message is enciphered corresponds to the laws of the universe, the intercepted messages to the evidence available, the keys for a day or a message to important constants which have yet to be determined. The correspondence is very close, but the subject matter of cryptography is very easily dealt with by discrete machinery, physics not so easily.”

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Shakespeare-Bacon’s Cipher

Shakespeare-Bacon’s Cipher
by Walt Whitman

I doubt it not; then more, immeasurably more,
In each old song bequeathed, in every noble page or text,
(Different, something unreck’d before, some unsuspected author,)
In every object—mountain, tree, and star—in every birth and life,
As part of each, finality of each, meaning, behind the ostent,
The mystic cipher waits infolded.

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Bletchley Park

Bletchley Park, also known as Station X, is an estate located in the town of Bletchley, in Buckinghamshire, England.  Since 1967, Bletchley has been part of Milton Keynes.

During World War II, Bletchley Park was the site of the United Kingdom’s main decryption establishment.  Ciphers and codes of several Axis countries were decrypted there, most importantly ciphers generated by the German Enigma and Lorenz machines.

The high-level intelligence produced at Bletchley Park, codenamed Ultra, is credited with having provided crucial assistance to the Allied war effort and with having shortened the war, though Ultra’s precise influence is still studied and debated.

Bletchley Park is now a museum run by the Bletchley Park Trust and is open to the public.  The main manor house is also available for functions and is licensed for ceremonies.  Part of the fees for hiring the facilities go to the Trust for use in maintaining the museum.

Five weeks before the outbreak of World War II, in Warsaw, Poland’s Biuro Szyfrów (Cipher Bureau) revealed its achievements in decrypting German Enigma ciphers to French and British intelligence.  The British used this information as the foundation for their own early efforts to decrypt Enigma.

The “first wave” of the Government Code and Cypher School (GC&CS) moved to Bletchley Park on 15 August 1939.  The main body of GC&CS, including its Naval, Military and Air Sections, was on the house’s ground floor, together with a telephone exchange, a teleprinter room, a kitchen and a dining room.  The top floor was allocated to MI6.  The prefabricated wooden huts were still being erected, and initially the entire “shooting party” was crowded into the existing house, its stables and cottages.  These were too small, so Elmers School, a neighbouring boys’ boarding school, was acquired for the Commercial and Diplomatic Sections.

A wireless room was set up in the mansion’s water tower and given the code name “Station X”, a term now sometimes applied to the codebreaking efforts at Bletchley as a whole.  The “X” simply denotes the number “10” in Roman numerals, as this was the tenth such station to be opened.  Due to the long radio aerials stretching from the wireless room, the radio station was moved from Bletchley Park to nearby Whaddon to avoid drawing attention to the site.

Listening stations – the Y-stations (such as the ones at Chicksands in Bedfordshire and Beaumanor Hall in Leicestershire, the War Office “Y” Group HQ) – gathered raw signals for processing at Bletchley.  Coded messages were taken down by hand and sent to Bletchley on paper by motorcycle couriers or, later, by teleprinter.  Bletchley Park is mainly remembered for breaking messages enciphered on the German Enigma cypher machine, but its greatest cryptographic achievement may have been the breaking of the German “Fish” High Command teleprinter cyphers.

The intelligence produced from decrypts at Bletchley was code-named “Ultra”.  It contributed greatly to the Allied success in defeating the U-boats in the Battle of the Atlantic, and to the British naval victories of Battle of Cape Matapan and the Battle of North Cape.

When the United States joined the war Churchill agreed with Roosevelt to pool resources and a number of American cryptographers were posted to Bletchley Park.  Whilst the British continued to work on German cyphers, the Americans concentrated on the Japanese ones.

The only direct action that the site experienced was when three bombs, thought to have been intended for Bletchley railway station, were dropped on 20 November 1940 – 21 November 1940.  One bomb exploded next to the dispatch riders’ entrance, shifting the whole of Hut 4 (the Naval Intelligence hut) two feet on its base.  As the huts stood on brick pillars, workmen just winched it back into position whilst work continued inside.

An outpost of Bletchley Park was set up at Kilindini, Kenya, to break and decipher Japanese codes.  With a mixture of skill and good fortune, this was successfully done: the Japanese merchant marine suffered 90 per cent losses by August 1945, a result of decrypts.

Most of the messages subjected to cryptanalysis at BP were enciphered with some variation of the Enigma cipher machine.

From 1943, Colossus, one of the earliest digital electronic computers, was constructed in order to break the German teleprinter on-line Lorenz cipher known as Tunny.  Colossus was designed and built by Tommy Flowers and his team at the Post Office Research Station at Dollis Hill.  The Colossus series of machines, of which there were ten by the end of the war, were operated at Bletchley Park in a section named the Newmanry after its head Max Newman.

Some 9,000 people were working at Bletchley Park at the height of the codebreaking efforts in January 1945, and over 10,000 worked there at some point during the war.  Among the famous mathematicians and cryptanalysts working there, perhaps the most influential and certainly the best-known in later years was Alan Turing.  A number of Bletchley Park employees were recruited for various intellectual achievements, whether they were chess champions, crossword experts, polyglots or great mathematicians.  In one, now well known instance, the ability to solve The Daily Telegraph crossword in under 12 minutes was used as a recruitment test.  The newspaper was asked to organise a crossword competition, after which each of the successful participants was contacted and asked if they would be prepared to undertake “a particular type of work as a contribution to the war effort”.  The competition itself was won by F H W Hawes of Dagenham who finished the crossword in less than eight minutes.

After the war, Churchill referred to the Bletchley staff as “My geese that laid the golden eggs and never cackled.”

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