Privacy-preserving biometrics for multi-factor authentication

A second user device comprising:

• a processor;
• a memory comprising a hash index table and an array index table;
• and
• a computer readable medium coupled to the process, the computer readable medium comprising code executable by the processor for performing operations comprising:
• generating a second public key and a second private key of a second public-private key pair;
• transmitting the second public key to a first user device, which stores an encrypted biometric template, the encrypted biometric template being a biometric template encrypted with a first public key of a first public-private key pair, wherein the first user device encrypts the encrypted biometric template with the second public key to form a double encrypted biometric template;
• receiving the double encrypted biometric template;
• decrypting the double encrypted biometric template using the second private key to obtain the encrypted biometric template;
• determining a test biometric template and encrypting the test biometric template;
• comparing the encrypted test biometric template and the encrypted biometric template to obtain an encrypted match score;
• and
• transmitting the encrypted biometric match score to a server computer, wherein the server computer decrypts the encrypted biometric match score to obtain a biometric match score, and allowing the second user device to perform a process if the biometric match score exceed a threshold.

A method comprising:

• generating, by a server computer, a first public-private key pair comprising a first public key and a first private key;
• transmitting, by the server computer, the first public key to a first user device, which encrypts a biometric template with the first public key to form an encrypted biometric template, encrypts the encrypted biometric template with a second public key of a second public-private key pair to form a double encrypted biometric template, and transfers the double encrypted biometric template to a second user device, which decrypts the double encrypted biometric template with a second private key of the second public-private key pair to obtain the encrypted biometric template, receives a test biometric template, encrypts the test biometric template using the first public key, and computes an encrypted score using the encrypted biometric template and the encrypted test biometric template;
• receiving, by the server computer, the encrypted score;
• decrypting, by the server computer the encrypted score using the first private key to form a biometric match score;
• determining, by the server computer, if the biometric match score exceeds a threshold;
• and
• performing a process on behalf of the second user device if the score exceeds the threshold.