Protecting polynomial hash functions from external monitoring attacks

A system for computing a polynomial hash function in a manner protected from side-channel attacks, the system comprising:

• a first adder circuit to combine, at a current iteration, a masked result value produced by a first multiplier circuit at a previous iteration and an input data block;
• the first multiplier circuit to produce, at the current iteration, a new masked result value by multiplying an output of the first adder circuit by a hash key;
• a first feedback circuit to feed the new masked result value to the first adder circuit;
• a second multiplier circuit to produce, at the current iteration, a new mask correction value by multiplying the hash key by a mask correction value produced at the previous iteration;
• a second feedback circuit to feed the new mask correction value to the second multiplier circuit;
• and
• a second adder circuit to produce an unmasked result value by applying the new mask correction value to the new masked result value.