Biometric techniques are more and more exploited in or- der to fasten and make more reliable the identification pro- cess. Recently, many proposals have been formulated com- bining cryptography and biometrics in order to increase the confidence in the system when biometric templates are stored for verification. In this work we present a biometric authentication tech- nique based on the combination of multiple biometric read- ings. The authentication control can be performed offline and the stored identifier does not disclose any information on the biometric traits of the identified person, so that even in case of loss or steal of the document, privacy is guaran- teed. Keywords: Biometric identification, Privacy, Secure sketch.