A chaotic cryptosystem based on time delay feedback Chua circuit for digital, image encryption

In the past few years, a number of image cryptosystems have been proposed. However, many of them have been shown to be insecure. In this paper we present a robust and efficient cryptosystem based on the synchronization of a chaotic time delay system to transmit a digital image in a secure way. It consists of two steps: the first one assures the transmitter/receiver synchronization, the second step focuses on the encryption/decryption procedure. The transmitter module consists of a chaotic generator which is the time delay feedback Chua circuit and an encryption mechanism (chaotic masking), in which the secret message (digital image) is added to the output of the chaotic generator. The receiver module consists of a nonlinear state observer design which is driven by only one of the states of the time delay feedback Chua circuit and a decryption mechanism. A secure analysis proves that this cryptosystem is robust to some best-known attacks. This efficiency relies to the properties of the chosen chaotic generator and the efficiency of the nonlinear observer.