Patent ID: 7137000

Claim:
An authentication method for authenticating an article in a device, the method comprising the steps of: reading an identification number stored on the article; reading an authentication number stored on the article; determining an input number based at least in part on the identification number; applying an authentication function to the input number to calculate an output number, wherein the authentication function is an encryption transformation of the input number, wherein the step of applying the authentication function further comprises the steps of: providing a first prime number, Q; providing a second prime number, M; the second prime number being a primitive element of the prime Galois Field of the first prime number; and calculating the output number according to the formula: output number=M N MOD Q, where N is the input number, wherein the second prime number is selected such that the second prime number is greater than 0, the second prime number is not equal to 1, and the second prime number is not equal to one-half of, the first prime number minus 1; and determining that the article is authentic only if the authentication number corresponds to the output number.