A binary logic circuit for determining y=x mod(2m−1), where x is an n-bit integer, y is an m-bit integer, and n>m, includes reduction logic configured to reduce x to a sum of a first m-bit integer β and a second m-bit integer γ; and addition logic configured to calculate an addition output represented by the m least significant bits of the following sum right-shifted by m: a first binary value of length 2m, the m most significant bits and the m least significant bits each being the string of bit values represented by β; a second binary value of length 2m, the m most significant bits and the m least significant bits each being the string of bit values represented by γ; and the binary value 1.