Method of encrypting digital data, a method of masking a biometric print, and application to making a security document secure

Abstract

The invention relates to a method of masking a plain datum b having n bits. The inventive method is characterised in that a masked datum m is produced using the following masking function: (I), wherein p is a prime number, bi is the bit at position i of plain datum b, and qi is the prime number at position i in a set of prime numbers (q1, . . . , qn) The invention also relates to a method of masking a biometric print, consisting in: determining a set of s real minutiae which are characteristic of the print; mixing and arranging the real minutiae with t false minutiae; and forming a mixed biometric datum b having n=s+1 bits, such that, for any i: bi=1 if position i corresponds to a real minutia, and bi=0 if position i corresponds to a false minutia. The invention can be used to secure a security document such as a bank cheque. m = ∏ i = 1 n ⁢ ⁢ q i b i ⁢ mod ⁢ ⁢ p ( I )

Dependencies are inferred from the claim text.