Consumable authentication protocol and system
First Claim
1. A consumable authentication protocol for validating the existence of an untrusted authentication chip, the protocol includes the steps of:
- calling a test function with a known incorrect value, one or more times, in a trusted authentication chip to generate an expected invalid response;
in the event that the expected invalid response is not received considering the untrusted authentication chip to be invalid;
otherwise, generating a secret random number and calculating a signature for the random number using a signature function, in the trusted authentication chip;
encrypting the random number and the signature using a symmetric encryption function using a first secret key, in the trusted authentication chip;
passing the encrypted random number and signature from the trusted authentication chip to an untrusted authentication chip;
decrypting the encrypted random number and signature with a symmetric decryption function using the first secret key, in the untrusted authentication chip;
calculating a signature for the decrypted random number using the signature function in the untrusted authentication chip;
comparing the signature calculated in the untrusted authentication chip with the signature decrypted;
in the event that the two signatures match, encrypting the decrypted random number together with a data message read from the untrusted chip by the symmetric encryption function using a second secret key and returning it together with the data message to the trusted authentication chip as part of the test function;
encrypting the random number together with the data message by the symmetric encryption function using the second secret key, in the trusted authentication chip;
comparing the two versions of the random number encrypted together with the data message using the second key, in the trusted authentication chip;
in the event that the two versions match, considering the untrusted authentication chip and the data message to be valid;
otherwise, considering the untrusted authentication chip and the data message to be invalid.
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Accused Products
Abstract
This invention concerns a consumable authentication protocol for validating the existence of an untrusted authentication chip, as well as ensuring that the authentication chip lasts only as long as the consumable. In a further aspect it concerns a consumable authentication system for the protocol. A trusted authentication chip has a test function; and the untrusted authentication chip has a read function to test data from the trusted chip, including a random number and its signature, encrypted using a first key, by comparing the decrypted signature with a signature calculated from the decrypted random number. In the event that the two signatures match, it returns a data message and an encrypted version of the data message in combination with the random number, encrypted using the second key. The test function operates to encrypt the random number together with the data message using a second secret key, compare the two versions of the random number encrypted together with the data message using the second key. In the event that the two versions match, the untrusted authentication chip and the data message are considered to be valid; otherwise, they are considered to be invalid.
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Citations
22 Claims
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1. A consumable authentication protocol for validating the existence of an untrusted authentication chip, the protocol includes the steps of:
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calling a test function with a known incorrect value, one or more times, in a trusted authentication chip to generate an expected invalid response; in the event that the expected invalid response is not received considering the untrusted authentication chip to be invalid; otherwise, generating a secret random number and calculating a signature for the random number using a signature function, in the trusted authentication chip; encrypting the random number and the signature using a symmetric encryption function using a first secret key, in the trusted authentication chip; passing the encrypted random number and signature from the trusted authentication chip to an untrusted authentication chip; decrypting the encrypted random number and signature with a symmetric decryption function using the first secret key, in the untrusted authentication chip; calculating a signature for the decrypted random number using the signature function in the untrusted authentication chip; comparing the signature calculated in the untrusted authentication chip with the signature decrypted; in the event that the two signatures match, encrypting the decrypted random number together with a data message read from the untrusted chip by the symmetric encryption function using a second secret key and returning it together with the data message to the trusted authentication chip as part of the test function; encrypting the random number together with the data message by the symmetric encryption function using the second secret key, in the trusted authentication chip; comparing the two versions of the random number encrypted together with the data message using the second key, in the trusted authentication chip; in the event that the two versions match, considering the untrusted authentication chip and the data message to be valid; otherwise, considering the untrusted authentication chip and the data message to be invalid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification