Upper Bounds on Differential Characteristics in Twofish
Twofish Technical Report #1, August 17, 1998.
ABSTRACT: In our original paper, the Twofish block cipher was introduced, and initial estimates of an upper bounds on the probability of a 12-round differential were given. These results used an imperfect model of Twofish. We present an improved model, and show that any 12-round differential characteristic has a probability of at most 2-102.8.