Patent ID: 7509292

Claim:
A method for validating the authenticity of an untrusted chip, the method includes the steps of: a) generating a random number and applying an asymmetric encrypt function to the random number using a public key to produce a first variable; b) passing the first variable to the untrusted chip; c) receiving a third variable together with a data message read from the untrusted chip, the third variable having been generated, in the untrusted chip, by a process including: d) decrypting the first variable with an asymmetric decrypt function using a secret key to produce a second variable, the public and secret keys being a public-private key pair; e) applying the asymmetric encrypt function to the second variable together with the data message using the secret key to produce the third variable; f) decrypting the third variable with the asymmetric decrypt function and using the public key to generate a fourth variable and comparing the fourth variable with the generated random number and the received data message; g) in the event of a match, considering the untrusted chip and the data message to be valid; otherwise considering the untrusted chip and the data message to be invalid.