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In cryptography, Treyfer is a block cipher/MAC designed in 1997 by Gideon Yuval. Aimed at smart card applications, the algorithm is extremely simple and compact; it can be implemented in just 29 bytes of 8051 machine code. Treyfer has a rather small key size and block size of 64 bits each. All operations are byte-oriented, and there is a single 8×8-bit S-box. The S-box is left undefined; the implementation can simply use whatever data is available in memory. In each round, each byte has added to it the S-box value of the sum of a key byte and the previous data byte, then it is rotated left one bit. The design attempts to compensate for the simplicity of this round transformation by using a large number of rounds: 32. Due to the simplicity of its key schedule, using the same 8 key bytes in each round, Treyfer was one of the first ciphers shown to be susceptible to a slide attack. This cryptanalysis, which is independent of the number of rounds and the choice of S-box, requires 232 known plaintexts and 244 computation time. ==Implementation== A simple implementation of Treyfer can be done as follows: #include #define NUMROUNDS 32 extern uint8_t const Sbox(); void treyfer_encrypt(uint8_t text(), uint8_t const key()) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Treyfer」の詳細全文を読む スポンサード リンク
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