GENERALIZED CONTINUED FRACTION BASED ASYNCHRONOUS STREAM CIPHER FOR IMAGE PROTECTION
In this paper, we are particulary interested by image protection. The conventional encryption standard may be not applicable to images, due to the digital images properties which are characterized with some intrinsic features such as highly pixel redundancy and correlation. We propose a new asynchronous stream cipher based on generalized continued fraction (GCF). The proposed scheme is resistant to statistic attack, differential attack and some other known attacks. Experimental results prove that our scheme is efﬁcient and secure.
With the advancements of communication technologies and the fascinating developments in digital image processing, the real-time secure image transmission over public networks such as the Internet and through wireless networks need to be secure. Thus, to make use of the communication infrastructure already developed and to maintain the secrecy, cryptographic techniques need to be applied [1, 2]. Cryptographic approaches are therefore critical for secure multimedia content storage and distribution over open networks such as the Internet and wireless networks. In this paper, we are particulary interested by image protection. The conventional cryptographic, such as DEA, AES and RSA may not be good candidates, especially for fast and real-time communication applications. In recent years, several stream cipher methods have been proposed. Some of them are synchronous like the chaos-based image encryption system with stream cipher structure [13, 16, 21, 22, 7]. Other are asynchronous, and the advantage of these techniques is that if ciphertext digits are dropped or added, then the decipher stream can self-heal by re-synchronization, and result errors are limited in a few plaintext digits. Furthermore, asynchronous stream ciphers have statistically a better diffusion than synchronous stream ciphers. In this paper, a new asynchronous stream cipher based on the use of the generalized continued fraction (GCF) to modify the pixel’s value is proposed.
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