We develop a method for performing boolean convolutions efficiently in word RAM model of computation, having a word size of w = Ω(log n) bits, where n is the input size. The technique is applied to approximate string matching under Hamming distance. The obtained algorithms are the fastest known. In particular, we reduce the complexity of the Amir et al. [1] algorithm for k-mismatches from O(n √ k log k) to O(n + n k/w log k).