Cryptanalysis of Boolean permutation-based key escrow scheme

Wu and Varadharajan [Computers and Electrical Engineering 25(4) 1999] proposed a fast public key escrow scheme. The security of this system is based on a special class of trapdoor Boolean permutations that can be constructed efficiently. In this paper, we show that this proposed class of Boolean permutations can be easily inverted without the knowledge of the secret key parameters. This allows the cryptanlyst to efficiently recover the session key using the known public key parameters.