Image Encryption Techniques Using Chaotic Schemes: a Review

Cryptography is about communication in the presence of an adversary. It encompasses many problems like encryption, authentication, and key distribution to name a few. The field of modern cryptography provides a theoretical foundation based on which one can understand what exactly these problems are, how to evaluate protocols that purport to solve them and how to build protocols in whose security one can have confidence. Advanced digital technologies have made multimedia data widely available. Recently, multimedia applications become common in practice and thus security of multimedia data has become main concern. The basic issues pertaining to the problem of encryption has been discussed and also a survey on image encryption techniques based on chaotic schemes has been dealt in the present communication. The chaotic image encryption can be developed by using properties of chaos including deterministic dynamics, unpredictable behavior and non-linear transform. This concept leads to techniques that can simultaneously provide security functions and an overall visual check, which might be suitable in some applications. Digital images are widely used in various applications, that include military, legal and medical systems and these applications need to control access to images and provide the means to verify integrity of images. Keywords—image encryption, chaotic schemes INTRODUCTION: The most ancient and basic problem of cryptography is secure communication over an insecure channel. Party A wants to send to party B a secret message over a communication line, which may be tapped by an adversary. The recent advances in technology, especially in computer industry and communications, allowed potentially enormous market for distributing digital multimedia content through the Internet. However, the proliferation of digital documents, image processing tools, and the worldwide availability of Internet access has created an ideal medium for copyright fraud and uncontrollable distribution of multimedia such as image, text, audio, and video content [2]. Another major challenge now is how to protect the intellectual property of multimedia content in multimedia networks. To deal with the technical challenges, the two major image security technologies are under use: (a) Image encryption techniques to provide end-to-end security when distributing digital content over a variety of distributions systems, and (b) Watermarking techniques as a tool to achieve copyright protection, ownership trace, and authentication. In this paper, the current research efforts in image encryption techniques based on chaotic schemes are discussed. SECURITY ISSUE: Multimedia security in general is provided by a method or a set of methods used to protect the multimedia content. These methods are heavily based on cryptography and they enable either communication security, or security against piracy (Digital Rights Management and watermarking), or both. Communication security of digital images and textual digital media can be accomplished by means of standard symmetric key cryptography. Such media can be treated as binary sequence and the whole data can be encrypted using a cryptosystem such as Advanced Encryption Standard (AES) or Data Encryption Standard (DES) [3]. In general, when the multimedia data is static (not a real-time streaming) it can treated as a regular binary data and the conventional encryption techniques can be used. Deciding upon what level of security is needed is harder than it looks. To identify an optimal security level, the cost of the multimedia information to be protected and the cost of the protection itself are to be compared ISSN: 0975-5462 2359 Monisha Sharma et. al. / International Journal of Engineering Science and Technology Vol. 2(6), 2010, 2359-2363 carefully. At present, there are many available image encryption algorithms such as Arnold map, Tangram algorithm[5], Baker’s transformation[6], Magic cube transformation[7], and Affine transformation[8] etc . In some algorithms, the secret-key and algorithm cannot be separated effectively. This does not satisfy the requirements of the modern cryptographic mechanism and are prone to various attacks. In recent years, the image encryption has been developed to overcome above disadvantages as discussed in [2, 3, and 4]. IMAGE ENCRYPTION TECHNIQUES: In this section, a few newly proposed techniques for image encryption, based on chaotic schemes which will improve the complexity of algorithm as well as make the key stronger has been introduced. First section deals with already existing image encryption techniques based on chaotic schemes in spatial domain where as latter part deals with some paper in frequency domain.