1. An enrollment 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 further comprising a step ( 120 ) to encode the vectors using an enrollment code (enc_enrol), the permutation being applied to the encoded vectors, said encoding comprising: converting each bit (m) of the mask vector (M) into a sequence of several bits representing the encoding of said bit (m) of the mask vector (M), such that a mean weight of the sequences of bits is constant or statistically constant irrespective of the values of the bits (m) of the mask vector; and converting each bit (i) of the information vector (I) into a sequence representing the encoding of said bit (i) of the information vector (I) and comprising at least one bit drawn randomly (a), the randomly drawn at least one bit following a same law of distribution as the bits of the information vector.