on a blockverschlu00fcsselungsalgorithmus with rundenwiederholung based method and device for executing the method

摘要

The procedures operates with an algorithm based on numbering, with repeated rounds. Within the process additional rounds are inserted, having no effect on the operation of the algorithm. These are undetectable, but act to prevent attack on the encoding by differential fault analysis. The procedure is based on a numbering algorithm with repetition of rounds, using a master key with regard to which sub-keys (Ki) are generated. These sub-keys are injected into the rounds (i). The algorithm further includes at least one pair of supplementary rounds formed by the first and second rounds (r', r) which have no use in the operation of the algorithm. Further random sub-keys (K', K) are applied to these rounds. These supplementary rounds are rendered undetectable within the operation of the algorithm.