The Indistinguishability of the XOR of k Permutations

Abstract : Given k independent pseudorandom permutations f(1), ... , f(k) over {0, 1}(n), it is natural to define a pseudorandom function by XORing the permutations f(1) circle plus... circle plus f(k). In [9] Stefan Lucks studied the security of this PRF. In this paper we improve the security bounds of [9] by using different proof techniques.