Cryptanalysis of Cryptosystems based on Remote Chaos Replication

In the last five years, many cryptosystems based on the chaos phenomenon have been proposed. Most of them use chaotic maps, i.e., the discrete-time chaos. The recent announcement of a cryptosystem based on continuous-time chaos that is generated by a very simple electronic circuit known as Chua’s circuit passed unrecognized by a large part of the cryptographic community. It is an analog to the Vernam-cipher system, but uses auto-synchronization through remote replication of the chaotic masking signal. After the introductory description of continuous-time chaotic systems and their synchronization a general definition and discussion of cryptosystems based on remote chaos replication is given. A cryptanalytic attack for these systems is developed that can break the cryptosystem using Chua’s circuit for all types of information-bearing signals.