Editing Known-plaintext attack (section)

{{short description|Attack model for cryptanalysis with access to both plaintext and ciphertext}}
The '''known-plaintext attack''' ('''KPA''') is an [[attack model]] for [[cryptanalysis]] where the attacker has access to both the [[plaintext]] (called a '''crib''') and its [[encryption|encrypted]] version ([[ciphertext]]). These can be used to reveal [[Cryptographic key|secret keys]] and [[code book]]s.  The term "crib" originated at [[Bletchley Park]], the British [[World War II]] decryption operation, where it was defined as:{{Blockquote|A plain language (or code) 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.<ref>[[Gordon Welchman]], ''The Hut Six Story: Breaking the Enigma Codes'', p. 78.</ref><ref>Michael Smith, "How It Began: Bletchley Park Goes to War," in [[B. Jack Copeland]], ed., ''Colossus: The Secrets of Bletchley Park's Codebreaking Computers''.</ref>|{{Citation
 | title = The Bletchley Park 1944 Cryptographic Dictionary formatted by Tony Sale, 2001 | url = https://www.codesandciphers.org.uk/documents/cryptdict/cryptxtt.pdf | page = 22 }} }}