Patent ID: 7908641
Filing Date: 2011-03-15
Classification: G06F,H04L

Abstract:
1. An apparatus for determining a result of a modular exponentiation within a cryptosystem with a first key and a second key, comprising: an input stage for providing the first key and the second key; a randomization auxiliary number calculator for calculating a randomization auxiliary number on the basis of a product of the first key and the second key less 1 and for writing the randomization auxiliary number in a randomization auxiliary number register; a processor for obtaining a random number and for combining a product of the random number and the randomization auxiliary number with the first or the second key in order to obtain a randomized exponent and for writing the randomized exponent in a randomized exponent register; a result calculator for calculating the result of the modular exponentiation using the randomized exponent; and an output stage for outputting the result, wherein the apparatus is a cryptochip comprising the randomization auxiliary number register and the randomized exponent register.