Authentication of consumable items
First Claim
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1. 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.
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Abstract
This invention concerns a consumable authentication method for validating the existence of an untrusted chip. A random number is encrypted using a first key and sent to an untrusted chip. In the untrusted chip it is decrypted using a secret key and re-encrypted together with a data message read from the untrusted chip. This is decrypted so that a comparison can be with the generated random number and the read data message.
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Citations
9 Claims
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1. A method for validating the authenticity of an untrusted chip, the method includes the steps of:
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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. - View Dependent Claims (2, 3, 4, 5)
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6. A system including:
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a random number generator; an asymmetric encryptor to encrypt generated random numbers with an asymmetric encryption function and using a public key to produce a first variable; an untrusted chip configured to; receive and decrypt the first variable with an asymmetric decrypt function and using a secret key to produce a second variable, the public and secret keys being a public-private key pair; reading a data message from the untrusted chip; apply the asymmetric encrypt function to the second variable together with a data message using the secret key to produce a third variable; and transmit both the third variable and the data message to a testing component; and the testing component configured to; decrypt the third variable with the asymmetric decrypt function and using the public key to produce a fourth variable; compare the fourth variable with the generated random number and the data message; and in the event of a match, generate a value indicating validity of the untrusted chip, otherwise generating a value indicating invalidity of the untrusted chip. - View Dependent Claims (7, 8, 9)
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Specification