Cryptanalysis of the Enigma.

During World War II, the Allies used known-plaintexts in their successful cryptanalysis of the Enigma machine cipher.

It has sometimes been erroneously stated that Alan Turing designed Colossus to aid the Cryptanalysis of the Enigma machine.

Knox worked in 'the Cottage', next door to the Bletchley Park mansion, as head of a research section, which contributed significantly to cryptanalysis of the Enigma.

He concentrated on cryptanalysis of the Enigma, with Dilly Knox, a senior GCCS codebreaker.

As with the entirely separate Cryptanalysis of the Enigma, it was German operational shortcomings that allowed the initial diagnosis of the system, and a way into decryption.

One codebreaker concerned with Cryptanalysis of the Enigma, John Herivel, discovered what was soon dubbed the Herivel tip or Herivelismus.

Also important, often overwhelmingly so, are mistakes (generally in the design or use of one of the protocols involved; see Cryptanalysis of the Enigma for some historical examples of this).

Introduction of the 4-rotor machine was preventing cryptanalysis of the Enigma, so the Allies were eager to get their hands on one to discover (and exploit) any weaknesses in the new system.

Much of the German cipher traffic was encrypted on the Enigma machine, hence the term "Ultra" has often been used almost synonymously with "Cryptanalysis of the Enigma".

Jeffreys was put in charge of a small section manufacturing perforated sheets for use in the cryptanalysis of the Enigma, a task which took over three months, completed on 7 January 1940.

The British provided technical information on Cryptanalysis of the Enigma as well as current British HF/DF procedures but not, at this stage, the full derived Ultra intelligence.

For a time, this change in encryption between submarines caused considerable difficulty for Allied codebreakers; it took ten months before Shark traffic could be read (see also Ultra codebreaking and Cryptanalysis of the Enigma).

He had previously been involved with GC&CS at Bletchley Park from February 1941 in an attempt to improve the Bombes that were used in the Cryptanalysis of the Enigma German cipher machine.

Mechanical encryption devices such as Enigma made these attacks much more difficult (although, historically, Polish cryptographers were able to mount a successful ciphertext-only cryptanalysis of the Enigma by exploiting an insecure protocol for indicating the message settings).

Cryptanalysis 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.