1. An enrolment method ( 100 ) for enrolling biometric data (I, M) in a database ( 10 ), each data item comprising a binary information vector (I) on a biometric feature, and a binary mask vector (M), determining those bits (i) of the information vector to be taken into account for data comparison, the method comprising the application ( 130 ) of permutation to the bits of the information vector (I) and of the mask vector (M), the method being characterized in that it further comprises a step ( 120 ) to encode the vectors using a so-called enrolment code (enc_enrol), the permutation being applied to the encoded vectors, and the said encoding comprising: the representation of each bit (m) of the mask vector (M) in a sequence of several bits, such that the mean weight of the representations of all the bits of the mask vector (M) is constant or statistically constant irrespective of the values of the bits (m) of the mask vector; and the representation of each bit (i) of the information vector (I) in a sequence comprising at least one bit drawn randomly (a), the randomly drawn bits following the same law of distribution as the bits of the information vector.