Method implemented by a processing unit having access to a biometric database

An identity checking method implemented by a checking system communicating with processing circuitry configured to implement a method that includes

• receiving a first biometric datum and a query asking whether the first biometric datum is referenced in a database, the database comprising reference biometric data associated with respective sets of random elements that are disjoint, each set of random elements comprising a plurality of random elements,
• searching for a second biometric datum that corresponds to the first biometric datum among the reference biometric data, and
• generating a response to the query, the response containing a random element satisfying the following conditions:
• when the second biometric datum is found in the search, the random element is an element from the set of random elements associated with the second biometric datum,
• when the second biometric datum is not found in the search, the random element does not belong to any of the sets of random elements associated with the reference biometric data, and
• the random element is different from a previous random element contained in a previous response to a previous query asking whether a previous biometric datum is referenced in the database, both when the previous random element is an element from one of the sets of random elements and when the previous random element does not belong to any of the sets of random elements, the identity checking method comprising:
• for any reference biometric datum, receiving a datum representative of the set of random elements associated with the reference biometric datum, following enrollment of the reference biometric datum in the database, and storing the datum representative of the set of random elements associated with the reference biometric datum in a memory;
• transmitting the query asking whether the first biometric datum is referenced in a database to the processing circuitry;
• receiving the response to the query;
• and
• verifying existence, in the memory, of a datum representative of a set of random elements that comprises the random element contained in the response.

A biometric data management system comprising:

• a communication interface configured to:
• receive a first biometric datum and a query asking whether the first biometric datum is referenced in a database, the database comprising reference biometric data associated with respective sets of random elements that are disjoint, each set of random elements comprising a plurality of random elements, and
• send a response to the query;
• and
• processing circuitry configured to:
• search for a second biometric datum that corresponds to the first biometric datum among the reference biometric data, and
• generate the response to the query, the response containing a random element, wherein the random element satisfies the following conditions:
• when the second biometric datum is found in the search, the random element is an element from the set of random elements associated with the second biometric datum,
• when the second biometric datum is not found in the search, the random element does not belong to any of the sets of random elements associated with the reference biometric data, and
• the random element is different from a previous random element contained in a previous response to a previous query asking whether a previous biometric datum is referenced in the database, both when the previous random element forms part of one of the sets of random elements and when the previous random element does not belong to any of the sets of random elements associated with the reference biometric data, wherein
• when the second biometric datum is not found in the search, the random element contained in the response is generated by the processing circuitry after the searching.