Cryptanalysis of the Parameterized Improved Fast Encryption Algorithm for Multimedia

for Multimedia (PIFEA-M) is a fast cipher recently proposed by Chefranov (IEEE communications letters, Vol. 12, No. 6, June 2008) to resist an implementation dependent differential attack on earlier versions of the cipher. In this paper we show that a similar differential style attack can still break PIFEA-M with a very low data and computational complexity. Index Terms—Cryptanalysis, multimedia encryption, FEA-M, IFEA-M, PIFEA-M. cipher requires at least O(272) operations, which is practically infeasible using current technologies. In this paper we show that, under the same assumptions, PIFEA-M is still suspectable to differential attacks. Let (P j i,Cj i) denote a plaintext-ciphertext pair produced by i-th encryption in session j. Given the pairs (P 1 1,C1 1), (P 2 1,C2 1), (P 1 2,C1 2) and (P 2 2,C2 2), we show that the attacker can recover all other successive plaintexts Pi, i ≥ 3 from both sessions with very small computational complexity. I