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IMCS/Publications/CSJM/Issues/CSJM v.11, n.3 (33), 2003/

Fast DDP-Based Ciphers: Design and Differential Analysis of Cobra-H64

Authors: N.A. Moldovyan
Keywords: Data-dependent operations, controlled permutations, data-dependent permutations, differential characteristics, fast hardware encryption, block cipher.

Abstract

Use of the controlled operations is considered as a new approach to the design of fast hardware-oriented ciphers. Data-dependent (DD) permutations and DD two-place operations are used in a new ten-round cipher named Cobra-H64 which is fast and cheap when implemented in hardware. The peculiarity of the iterated 64-bit cipher Cobra-H64 is the very fast encryption in the case of frequent change of keys, since no preprocessing is used to perform key scheduling. The whole secret key is directly used in each round. The Cryptosystem Cobra-H64 is characterized by high parallelism of the data transformation. Time delay of one round is 15t+, where t+ is the time delay of the XOR operation. The analysis performed has shown that Cobra-H64 is secure against differential attacks.

N.A. Moldovyan,
Specialized Center of Program Systems "SPECTR",
Kantemirovskaya str., 10, St. Petersburg 197342, Russia;
ph./fax.7-812-2453743,
E-mail :



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