10-Round Feistel is Indifferentiable from an Ideal Cipher

We revisit the question of constructing an ideal cipher from a random oracle. Coron et al. (Journal of Cryptology, 2014) proved that a 14-round Feistel network using random, inde-pendent, keyed round functions is indifferentiable from an ideal cipher, thus demonstrating the feasibility of such a construction. Left unresolved is the best possible efficiency of the transfor-mation. We improve upon the result of Coron et al. and show that 10 rounds suffice.