Patent attributes
A method of validating a consumable authentication chip is provided having the steps of: numerously calling a trusted chip's test function with an incorrect value to generate an invalid response or not generate the response thereby invalidating the consumable chip; if generated, in the trusted chip, generating a secret random number, calculating its signature and symmetrically encrypting the number/signature using a first secret key; calling the consumable chip's read function with the encrypted number/signature to symmetrically decrypt the encrypted number/signature using the first key, calculate the decrypted number's signature, compare the signatures, and if they match, symmetrically encrypt the decrypted random number and a data message using a second secret key; calling the trusted chip's test function with the message and the encrypted number/message to symmetrically encrypt the number and message using the second key, compare the encrypted numbers/messages, validate the consumable chip if they match, and invalidate otherwise.
