# Cipher

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**Stream cipher attack**— Stream ciphers, where plaintext bits are combined with a cipher bit stream by an exclusive or operation (xor), can be very secure if used properly. However they are vulnerable to attack if certain precautions are not followed:*keys must never be… …112

**Bacon's cipher**— or the Baconian cipher is a method of steganography (a method of hiding a secret message as opposed to a true cipher) devised by Francis Bacon. A message is concealed in the presentation of text, rather than its content.To encode a message, each… …113

**Two-square cipher**— The Two square cipher is a manual symmetric encryption technique. It was developed to ease the cumbersome nature of the large encryption/decryption matrix used in the four square cipher while still being slightly stronger than the Playfair cipher …114

**Combined Cipher Machine**— CSP 1600, the replacement stepping unit to adapt the ECM Mark II to CCM The Combined Cipher Machine (CCM) (or Combined Cypher Machine) was a common cipher machine system for securing Allied communications during World War II and for a few years… …115

**Scream (cipher)**— The Scream cipher is a word based stream cipher developed by Shai Halevi, Don Coppersmith and Charanjit Jutla from IBM.The cipher is designed as a software efficient stream cipher. The authors describe the goal of the cipher to be a more secure… …116

**Autokey cipher**— An autokey cipher (also known as the autoclave cipher) is a cipher which incorporates the message (the plaintext) into the key. There are two forms of autokey cipher: key autokey and text autokey ciphers. A key autokey cipher uses previous… …117

**D'Agapeyeff cipher**— The D Agapeyeff cipher is an as yet unbroken cipher that appears in the first edition of Codes and Ciphers, an elementary book on cryptography published by the Russian born English cartographer Alexander D Agapeyeff in 1939. Offered as a… …118

**Nihilist cipher**— In the history of cryptography, the Nihilist cipher is a manually operated symmetric encryption cipher originally used by Russian Nihilists in the 1880s to organize terrorism against the czarist regime. The term is sometimes extended to several… …119

**Rabbit (cipher)**— Rabbit is a high speed stream cipher first presented [M. Boesgaard, M. Vesterager, T. Pedersen, J. Christiansen, O. Scavenius. Rabbit: A High Performance Stream Cipher. Proc. FSE 2003. Springer LNCS 2887, pp. 307 329 (… …120

**Nimbus (cipher)**— This article is about the block cipher. For other uses, see Nimbus (disambiguation). Nimbus General Designers Alexis Machado First published 2000 Cipher detail Key sizes 128 bits Block sizes …