Known-plaintext attack

As a crib ( German: probable word, French: mot probable; literally translated: Cheat Sheet) in cryptography is one plaintext phrase referred to by the code breakers white, suspected or guesses that it occurs in a ciphertext encrypted.

If this is indeed the case and succeeds example, by pattern search to tap the location ( position) of the cribs in the ciphertext, then a break in the encryption succeeded, often sufficient to decipher the text.

Cribs served the British code breakers at Bletchley Park as a tool to break the German Enigma encryption during the Second World War. For this purpose they used as a primary tool specially designed to electro-mechanical Entzifferungsmaschine, called the " Turing - bomb."