Patent ID: 8605899

Claim:
A method for generating a second asymmetric cryptographical key pair, wherein a first private key (G 0 ) forms a first asymmetric cryptographical key pair (K 0 ) together with a first public key (O 0 ), wherein the method comprises the following steps: receiving a user identifier, calculating a second private key (G 1 ), wherein a random value (z) and the user identifier are used in the calculation, calculating a second public key (O 1 ) from the second private key using an asymmetric cryptographical key generation method, wherein the second private key and the second public key form the second asymmetric cryptographical key pair (K 1 ), performing an admissibility check on the second private key using a check condition, wherein the check condition comprises the usability of the second private key for generating the second public key from the second private key using an asymmetric cryptographical key generation method, calculating the second public key from the second private key if the check condition is satisfied, calculating the second private key with a new random value and repeating the step of performing an admissibility check if the check condition is not satisfied, generating a first cipher (C_G 0 — O 1 ) by encrypting the first private key (G 0 ) with the second public key (O 1 ), storing the first cipher (C_G 0 — O 1 ), storing the random value in a database.