A concatenated coding scheme for biometric template protection

Cryptography may mitigate the privacy problem in biometric recognition systems. However, cryptography technologies lack error-tolerance and biometric samples cannot be reproduced exactly, rising the robustness problem. The biometric template protection system needs a good feature extraction algorithm to be a good classifier. But, an even effective feature extractor can give a very low-quality biometric channel (i.e. high Bit Error Rate (BER)). Using the Spectral Minutiae method to identify fingerprints is one of the examples, which gives a BER of 40 ~ 50% to most of the matching channels. Therefore, we propose a concatenated coding scheme based on erasure codes to achieve a robust and secure biometric recognition system. The key idea is to transmit more packets than needed for decoding and allow the erasure-encoded packet suffering high BER to be discarded. The erasure decoder can reconstruct the secret key by collecting enough surviving packets. By applying the spectral minutiae method in the FVC2000-DB2 fingerprint database, the unprotected system achieves an EER of 3.7% and our proposed coding scheme reaches an EER of 4.6% with a 798-bit secret key.