  The last decades have seen a growing interest in hash functions that allow
some sort of tolerance, e.g. for the purpose of biometric authentication. Among
these, the syndrome fuzzy hashing construction allows to securely store
biometric data and to perform user authentication without the need of sharing
any secret key. This paper analyzes this model, showing that it offers a
suitable protection against information leakage and several advantages with
respect to similar solutions, such as the fuzzy commitment scheme. Furthermore,
the design and characterization of LDPC codes to be used for this purpose is
addressed.
