1. A method of generating a biometric certificate of a user performed by a data processing device of a certifying authority, characterized in that it comprises a step of generating a certificate for said user comprising data related to the identity of the user and truncated authentication data of said user generated by a method of generating a biometric authentication datum, said method of generating a biometric authentication datum comprising steps of: acquiring first biometric data of said user; generating a first proof of knowledge of said first biometric data from the first acquired biometric data and from a pseudo-random function; generating a first truncated authentication datum by applying a truncation function to said first generated proof of knowledge.