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Propagation characteristics of RC5, RC6 and Twofish ciphers

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2003
Arıkan, Savaş
In this thesis, two finalists of the AES (Advanced Encryption Standard) contest, RC6 developed by Rivest et al, Twofish proposed by Schneier et al, and preceding algorithm of RC6 cipher, RC5, are studied. The strength of ciphers to cryptanalytic attacks is measured according to different criteria. The studied evaluation criteria are the avalanche criterion and its derivations. After theimplementation of the algorithms and the test procedures, they are compared with each other. Different test criteria, including avalanche criterion, avalanche weight distribution (AWD) for randomness of RC5, RC6 and Twofish algorithms are applied; and the S-boxes of the Twofish algorithm are analyzed according to nonlinearity criterion. The avalanche criteria results of RC6 and Twofish are compared with NIST (National Institute of Standards and Technology) Statistical Test Suite results.