An Efficient Known Plaintext Attack on FEA-M

Abstract

Yi et al. have proposed a cipher called the fast encryption algorithm for multimedia (FEA-M). Recently Mihaljević and Kohno pointed out that FEA-M is insecure. However, their attacks are not efficient: their chosen plaintext attack and known plaintext attack require 237-bit chosen plaintext and 260-bit known plaintext, respectively. In this paper we give an efficient known plaintext attack against FEA-M. Our attack requires only 228-bit known plaintext and about 233 XOR operations.