Data-dependent (DD) permutations (DDP) are discussed as a cryptographic primitive for the design of fast hardware, firmware, and software encryption systems. DDP can be performed with so called controlled permutation boxes (CPB) which are fast while implemented in cheap hardware. The latter defines the efficiency of the embedding of CPB in microcontrollers and microprocessors when adding a new instruction that allows one to perform DDP. Different types of fast software and firmware encryption algorithms combining DDP with fast arithmetic operations are described. The proposed ciphers are free of the key preprocessing that provides high performance in the case of frequent change of keys. Presented results show the ciphers are secure against differential analysis. Other attacks are also considered.
Nikolay A. Moldovyan, Peter A. Moldovyanu, Douglas