  Recently, a novel public key edcryption technique based on multiple chaotic
systems has been proposed. The scheme employs m-chaotic systmes and a set of
linear functions for key exchange over an insecure channel. The security of the
proposed algorithm grows as NPm, where M, P are the size of the key and the
computational commplexity fo the linear functions respectively. In this paper,
the fundamental weakness of the cryptosystme is pointed out and a successful
attack is described. Given the public keys and initial vector, one can
calculate the secret key based on Parsevala's theorem. Both theoretical and
experimental results show that the attacker can access to the secret key
without difficulty. The lack of security discourages the use of such algorithm
for practical application.
