This part of ISO/IEC 10118 specifies two hash functions that make use of modular arithmetic. These hash functions, believed to be resistant to collisions, compress messages of arbitrary but limited length into a hash code whose length is determined by the prime number used in the reduction function defined in Section 7.3. As a result, the hash code can easily be scaled to the input length of any mechanism (e.g., signature algorithm, identification scheme).
The hash functions specified in this part of ISO/IEC 10118, known as MASH-1 and MASH-2 (Modular Arithmetic Secure Hash), are particularly suitable for environments where implementations of sufficiently long modular arithmetic are already available. The two hash functions differ only in the exponent used in the round function.
