Patent ID: 11888984
Assignee: GIESECKE+DEVRIENT MOBILE SECURITY GMBH
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 9:
10. A method for implementing, in a microprocessor device, an obfuscated cryptographic operation constructed to process obfuscated parameters and generate an output, comprising the steps:
providing the microprocessor device with a partial implementation of the cryptographic operation lacking at least some parameters,
obfuscating the lacking at least some parameters in a processing device outside the microprocessor device and transferring the obfuscated parameters from the processing device to the microprocessor device,
implementing the lacking obfuscated parameters in the partial implementation so as to generate the obfuscated cryptographic operation,
wherein the obfuscated parameters are obfuscated in that they are encrypted according to an additive homomorphic cryptographic system,
wherein the parameters to be processed by the cryptographic operation comprise at least a secret key (d),
wherein at least the secret key (d) is obfuscated in that the secret key (d) is encrypted according to the additive homomorphic cryptographic system.