Biometric authentication system, template updating method therefor, storage medium, biometric authentication client device, and biometric authentication server device

A template updating method for a biometric authentication system that comprises a template storage configured to store a template used for concealing biometric information and a verification key storage configured to store a verification key used for verification of the concealed biometric information, the method comprising:

• generating, based on the biometric information, initial values of (i) the template and (ii) the verification key,
• storing the template in the template storage and storing the verification key in the verification key storage,
• generating an update value in the biometric authentication system;
• updating the template stored in the template storage by multiplying a value contained in the template by the update value;
• and
• updating the verification key stored in the verification key storage by multiplying a value contained in the verification key by the update value.

A non-transitory computer-readable storage medium storing at least one program to be executed in a biometric authentication system comprising a template storage configured to store a template used for concealing biometric information, a verification key storage configured to store a verification key used for verifying the concealed biometric information, and at least one processor, wherein the at least one program, when executed by the at least one processor, causes the biometric authentication system to:

• generate, based on biometric information, initial values of (i) the template and (ii) the verification key,
• store the template in the template storage and store the verification key in the verification key storage,
• generate an update value in the biometric authentication system,
• update the template stored in the template storage by multiplying a value contained in the template by the update value, and
• update the verification key stored in the verification key storage by multiplying a value contained in the verification key by the update value.

A biometric authentication client device comprising:

• at least one processor;
• and
• memory storing instructions,
• wherein the instructions, when executed by the at least one processor, cause the biometric authentication client device to:
• acquire input biometric information;
• transmit the biometric information to a biometric authentication server device to cause the biometric authentication server device to:
• generate, based on biometric information, initial values of (i) a template used for concealing biometric information and (ii) a verification key used for verification of the concealed biometric information;
• store the verification key in a verification key storage;
• transmit the template to the biometric authentication client device;
• store the template in a template storage;
• generate an update value;
• update the template stored in the template storage by multiplying a value contained in the template by the update value;
• and
• transmit the update value to a biometric authentication server device to cause the biometric authentication server device to update the verification key in the verification key storage by multiplying a value contained in the verification key by the update value.

A biometric authentication server device comprising:

• at least one processor;
• and
• memory storing instructions,
• wherein the instructions, when executed by the at least one processor, cause the biometric authentication server device to:
• generate, based on biometric information, initial values of (i) a template used for concealing biometric information and (ii) a verification key used for verification of the concealed biometric information;
• store the verification key in a verification key storage;
• transmit the template to the biometric authentication client device to cause the biometric authentication client device to:
• store the template in a template storage;
• generate an update value;
• update the template stored in the template storage by multiplying a value contained in the template by the update value;
• and
• transmit the update value to the biometric authentication server device;
• update the verification key stored in the verification key storage by multiplying a value contained in the verification key by the update value;
• and
• transmit the update value to the biometric authentication client device storing the template.