Patent ID: 7474748
Filing Date: 2009-01-06
Classification: G06F

Abstract:
1. A method for determining, in a way that is protected against spying, the modular inverse b of a value a in relation to a module n for a cryptographic application, comprising the steps: a) determining an auxiliary value β and an auxiliary module δ, which are relatively prime to each other, at least depending on the value a, the module n and at least one masking parameter r in such a way that at least one of the following holds: b) determining an auxiliary inverse β′ as the modular inverse of the auxiliary value β in relation to the auxiliary module δ, and c) determining the modular inverse b at least depending on the following values: wherein the modular inverse b is used to generate a secret private key for executing an RSA method, the secret private key being stored in a portable data storage.