Coron et al. in TCC 2010 proposed a 2n-bit queryPlease check and confirm the corresponding author is identified correctly.permutation by using an n-bit ideal cipher with an n-bit key in a Feistel type structure for three rounds (in: Micciancio (ed) Theory of cryptography, Springer, Berlin, Heidelberg, 2010). The authors showed n/2-bit queryPlease check and confirm whether the inserted country name is correct in affiliations 1 and 2.indifferentiable security. In this paper we improve their result by showing (n−2logn)-bit indifferentiable security, by using more sophisticated counting techniques. This result will help us design ideal permutations using queryPlease check and confirm whether the inserted running title is correct.block ciphers and deploy them in queryPlease provide and MSC codes.permutation-based cryptosystems such queryPlease check and confirm whether the inserted keywords are correct. as sponge constructions.