Patent ID: 7382875
Filing Date: 2008-06-03
Classification: H04L

Abstract:
1. A cryptographic method, in which a first entity generates, by means of a private key kept secret by the first entity, a proof verifiable by a second entity by means of a public key associated with said private key, wherein said method comprises a step in which at least one element of proof is at least partly generated by open digital processing of a data item that allows the second entity to verify a match between said element of proof and another element of proof, and that does not allow said private key to be recovered, wherein the method comprises: a first step in which the first entity generates a first element of proof by means of a first random number r kept secret by the first entity; a second step in which one or more common numbers are generated in association with the first element of proof, so that the first entity and the second entity has knowledge of said one or more common numbers; a third step in which the first entity generates an image y of said private key by combining at least a first private key integer with the first random number r and at least one of said common numbers; and a fourth step in which a second element of proof Y is generated by applying, to the image y of said private key, an open digital processing operation executable by any entity, so as to allow the second entity to verify a match of the first element of proof with the second element of proof Y by applying a first part of said public key to the second element of proof Y and at least a second part of said public key to the at least one of said common numbers.