On linear approximation of modulo sum
The general case for a linear approximation of the form "X-1+(...)+X-k mod 2(n'') -->"X-1 circle plus(...)circle plus X-k circle plus N" is investigated, where the variables and operations are n-bit based, and the noise variable N is introduced due to the approximation. An efficient and practical algorithm of complexity 0(n (.) 2(3(k-1))) to calculate the probability Pr{N} is given, and in some ca