Differential Characteristic Probability of Added Key on Modulo 2n Operation

Added key on modulo 2n operation－Y=X+Kmod2n is a code link which is often used in cipher algorithms, as SAFER++, RC6, Phelix and so on. In this paper, the Y=X+Kmod2n is analyzed with differential cryptanalysis. And the characters of structure, counting formulas of input and output differences and the keys is given for the first time, when the differential probability is to be 1, 1-1/2n-2, 1/2n-2, 1/2.