Patent ID: 7602920

Claim:
A method for secure loading of a key dedicated to securing a predetermined operation into a memory of a microchip of an embedded system, said dedicated key being contained in a security device that includes means for two-way communication with said microchip, wherein said memory of said microchip is adapted to store a symmetric secret encryption key and an asymmetric public key and said security device is adapted to store the symmetric secret encryption key and an asymmetric secret key corresponding to the public key of said microchip, said method comprising the steps of: authenticating said security device by generating a first random number using the microchip, transmitting the first random number to the security device, generating a second random number in the security device, generating in the security device a first cryptogram from said first and second random numbers by applying an asymmetric signature algorithm using said asymmetric secret key, transmitting at least the first cryptogram to said microchip, and authenticating the security device by verifying the first cryptogram in the microchip using said public key; authenticating said microchip to said security device by generating, in said microchip, a secret session key from said first random number by applying a symmetric encryption algorithm using said symmetric secret encryption key, generating in said microchip a second cryptogram by applying a symmetric encryption algorithm on said second random number, wherein said second random number is received by the microchip from the security device, using said secret session key, transmitting said second cryptogram to said security device, and authenticating said microchip in the security device by verifying said second cryptogram using said session key to obtain said second random number, said receiving said second random number by the micro chip from the security device and said transmitting said second cryptogram from the microchip to the security device being performed in response to a mutual authentication command which is received by said microchip; and transferring said dedicated key, encrypted by said session key, into said storage means of said microchip.