Quantization effects in biometric systems

The fundamental secret-key rate vs. privacy-leakage rate trade-offs for secret-key generation and transmission for i.i.d. Gaussian biometric sources are determined. These results are the Gaussian equivalents of the results that were obtained for the discrete case by the authors and independently by Lai et al. in 2008. Also the effect that binary quantization of the biometric sequences has on the ratio of the secret-key rate and privacy-leakage rate is considered. It is shown that the squared correlation coefficient must be increased by a factor of pi²/4 to compensate for such a quantization action, for values of the privacy-leakage rate that approach zero, when the correlation coefficient is close to zero.