S Box: Cryptography, Symmetric Key Algorithm, Block Cipher, Ciphertext, Claude Shannon, Confusion and Diffusion, Bit, Twofish, Key, Bruce Schneier, International Data Encryption Algorithm

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Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In cryptography, an S-Box (Substitution-box) is a basic component of symmetric key algorithms which performs substitution. In block ciphers, they are typically used to obscure the relationship between the key and the ciphertext - Shannon's property of confusion. In many cases, the S-Boxes are carefully chosen to resist cryptanalysis. In general, an S-Box takes some number of input bits, m, and transforms them into some number of output bits, n: an m×n S-Box can be implemented as a lookup table with 2m words of n bits each. Fixed tables are normally used, as in the Data Encryption Standard (DES), but in some ciphers the tables are generated dynamically from the key; e.g. the Blowfish and the Twofish encryption algorithms.

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Pagina's: 68, Paperback, Betascript Publishers