Theoretical cryptanalysis of the Klimov-Shamir number generator TF-1

الأصل · EN

The internal state of the Klimov-Shamir number generator TF-1 consists of four words of size w bits each, whereas its intended strength is 2²ʷ. We exploit an asymmetry in its output function to show that the internal state can be recovered after having 2ʷ outputs, using 2¹.⁵ʷ operations. For w=32 the attack is practical, but for their recommended w=64 it is only of theoretical interest.