Method of verification of a biometric authentication

1. A biometric data processing method implemented by a proof entity and a verification entity that are connected;

the proof entity having a candidate biometric data, a reference biometric data, a cryptographic footprint of the reference biometric data, a cryptographic footprint of the candidate biometric data; the verification entity having only a set of cryptographic footprints of reference biometric data of authorized users;

the method comprising steps of:

generation by data processing means of the proof entity of a zero-knowledge proof of the fact that the candidate biometric data and the reference biometric data match;

(a) transmission to the verification entity of said zero-knowledge proof, of the cryptographic footprint of the candidate biometric data, and of the cryptographic footprint of the reference biometric data;

(b) verification by data processing means of the verification entity that:

the zero-knowledge proof is valid, and

the received cryptographic footprint of the reference biometric data belongs to said set of cryptographic footprints of reference biometric data in the possession of the verification entity.

2. The method according to claim 1 , wherein the proof entity initially has only the reference biometric data and the cryptographic footprint of the reference biometric data, the method comprising the implementation by the data processing means of the proof entity of a preliminary step (al) of:

generation of the candidate biometric data from a biometric trait furnished by biometric acquisition means of the proof entity, and

generation of the cryptographic footprint of the candidate biometric data obtained.

3. The method according to claim 2 , wherein step (al) comprises the time-stamping by the data processing means of the proof entity of the candidate biometric data using a time marker, the cryptographic footprint generated in step (al) and transmitted in step (b) being that of the time-stamped candidate biometric data.

4. The method according to claim 3 , wherein said time marker is a nonce generated by the data processing means of the verification entity and transmitted to the proof entity.

5. The method according to claim 3 , wherein said zero-knowledge proof of the fact that the candidate biometric data and the reference biometric data match is a zero-knowledge proof of the fact that, given two cryptographic footprints and a time marker, there are reference biometric data and candidate biometric data such that:

the reference biometric data and the time-stamped candidate biometric data using the given time marker have the given cryptographic footprints for respective cryptographic footprints,

the reference biometric data and the candidate biometric data match.

6. The method according to claim 2 , comprising an earlier implemented step (a 0 ) of:

generation by data processing means of an authority entity of said reference biometric data from a reference biometric trait, and transmission thereof to the proof entity;

addition to said set of cryptographic footprints of reference biometric data of authorized users of the cryptographic footprint of the generated reference biometric data.

7. The method according to claim 6 , wherein step (a 0 ) further comprises the generation by the data processing means of the authority entity of the cryptographic footprint of said generated reference biometric data, and the transmission thereof to the proof entity; and the retransmission by the proof entity to the verification entity of said generated cryptographic footprint of said generated reference biometric data, in order to add reference biometric data of authorized users to said set of cryptographic footprints.

8. The method according to claim 1 , wherein the proof entity is a personal electronic device of an individual who is among the authorized users, such as a mobile device or chip card, the reference biometric data stored in the proof entity being that of said individual.

9. The method according to claim 8 , wherein each of said authorized users the proof entity is personal electronic device of an individual, such as a mobile device or chip card, the reference biometric data stored in the proof entity being that of said individual.

10. The method according to claim 6 , wherein the proof entity is a personal electronic device of an individual who is among the authorized users, such as a mobile device or chip card, the reference biometric data stored in the proof entity being that of said individual; and wherein the reference biometric trait from which said reference biometric data is generated in step (a 0 ) is that of the individual having the proof entity.

11. The method according to claim 1 , wherein the zero-knowledge proof is a cryptographic object of the zkSNARK type.

12. The method according to claim 1 , wherein step (a) comprises the preliminary verification that the candidate biometric data and the reference biometric data match; the candidate biometric data and the reference biometric data matching if the distance thereof according to a given comparison function is less than a predetermined threshold.

13. A biometric data processing assembly comprising a proof entity and a verification entity that are connected, characterized in that:

the proof entity comprises data processing means configured to generate a zero-knowledge proof of the fact that a candidate biometric data and a reference biometric data match, and to transmit to the verification entity said zero-knowledge proof, a cryptographic footprint of the candidate biometric data, and a cryptographic footprint of the reference biometric data;

the verification entity comprises data processing means configured to verify that the zero-knowledge proof is valid, and that the received cryptographic footprint of the reference biometric data belongs to a set of cryptographic footprints of reference biometric data of authorized users in the possession of the verification entity.

14. The assembly according to claim 13 , wherein the proof entity comprises biometric acquisition means, the data processing means of the proof entity being further configured to generate the candidate biometric data from a biometric trait furnished by the biometric acquisition means and the cryptographic footprint of the candidate biometric data obtained.

15. A non-transitory computer program product comprising code instructions for the execution of a method according to claim 1 of biometric data processing, when said method is executed on a computer.

16. A non-transitory storage means readable by computer equipment on which a computer program product comprises code instructions for the execution of a method according to claim 1 of biometric data processing.