A Non-adaptive Partial Encryption of Grayscale Images based on Chaos

AbstractResearch papers published in recent times have focused towards different kinds of image encryption techniques. Image encryption based on Chaos became very popular for cryptography since properties of Chaos are related to two basic properties of good cipher-Confusion and Diffusion. In this paper, A Non-adaptive Partial Encryption of Grayscale Images Based on Chaoshas been proposed. In Partial encryption speed and time is the main factor. We decompose the original grayscale image into its corresponding binary eight bit planes then encrypted using couple tent map based pseudorandom binary number generator (PRBNG). The four significant bit planes, determined by 5% level of significance on contribution of a bit-plane in determination of a pixel value, are encrypted using keys which are obtained by applying the recurrence relation of tent map based PRBNG. Then the four insignificant bit planes along with encrypted significant bit planes are combined to form the final cipher image. In order to evaluate performance, the proposed algorithm was measured through a series of tests to measure the security and effectiveness of the proposed algorithm. These tests includes visual test through histogram analysis, measures of central tendency and dispersion, correlation-coefficient analysis, key sensitivity test, key space analysis, information entropy test, Measurement of Encryption Quality – MSE, PSNR, NPCR, UACI. Experimental results show that the new cipher has satisfactory security and efficient

Hardware Implementation of a Secured Digital Camera with Built In Watermarking and Encryption Facility

The objective is to design an efficient hardware implementation of a secure digital camera for real time digital rights management (DRM) in embedded systems incorporating watermarking and encryption. This emerging field addresses issues related to the ownership and intellectual property rights of digital content. A novel invisible watermarking algorithm is proposed which uses median of each image block to calculate the embedding factor. The performance of the proposed algorithm is compared with the earlier proposed permutation and CRT based algorithms. It is seen that the watermark is successfully embedded invisibly without distorting the image and it is more robust to common image processing techniques like JPEG compression, filtering, tampering. The robustness is measured by the different quality assessment metrics- Peak Signal to Noise Ratio (PSNR), Normalized Correlation (NC), and Tampering Assessment Function (TAF). It is simpler to implement in hardware because of its computational simplicity. Advanced Encryption Standard (AES) is applied after quantization for increased security. The corresponding hardware architectures for invisible watermarking and AES encryption are presented and synthesized for Field Programmable Gate Array(FPGA).The soft cores in the form of Hardware Description Language(HDL) are available as intellectual property cores and can be integrated with any multimedia based electronic appliance which are basically embedded systems built using System On Chip (SoC) technology

A NOVEL JOINT PERCEPTUAL ENCRYPTION AND WATERMARKING SCHEME (JPEW) WITHIN JPEG FRAMEWORK

Due to the rapid growth in internet and multimedia technologies, many new commercial applications like video on demand (VOD), pay-per-view and real-time multimedia broadcast etc, have emerged. To ensure the integrity and confidentiality of the multimedia content, the content is usually watermarked and then encrypted or vice versa. If the multimedia content needs to be watermarked and encrypted at the same time, the watermarking function needs to be performed first followed by encryption function. Hence, if the watermark needs to be extracted then the multimedia data needs to be decrypted first followed by extraction of the watermark. This results in large computational overhead. The solution provided in the literature for this problem is by using what is called partial encryption, in which media data are partitioned into two parts - one to be watermarked and the other is encrypted. In addition, some multimedia applications i.e. video on demand (VOD), Pay-TV, pay-per-view etc, allow multimedia content preview which involves „perceptual‟ encryption wherein all or some selected part of the content is, perceptually speaking, distorted with an encryption key. Up till now no joint perceptual encryption and watermarking scheme has been proposed in the literature. In this thesis, a novel Joint Perceptual Encryption and Watermarking (JPEW) scheme is proposed that is integrated within JPEG standard. The design of JPEW involves the design and development of both perceptual encryption and watermarking schemes that are integrated in JPEG and feasible within the „partial‟ encryption framework. The perceptual encryption scheme exploits the energy distribution of AC components and DC components bitplanes of continuous-tone images and is carried out by selectively encrypting these AC coefficients and DC components bitplanes. The encryption itself is based on a chaos-based permutation reported in an earlier work. Similarly, in contrast to the traditional watermarking schemes, the proposed watermarking scheme makes use of DC component of the image and it is carried out by selectively substituting certain bitplanes of DC components with watermark bits. vi ii Apart from the aforesaid JPEW, additional perceptual encryption scheme, integrated in JPEG, has also been proposed. The scheme is outside of joint framework and implements perceptual encryption on region of interest (ROI) by scrambling the DCT blocks of the chosen ROI. The performances of both, perceptual encryption and watermarking schemes are evaluated and compared with Quantization Index modulation (QIM) based watermarking scheme and reversible Histogram Spreading (RHS) based perceptual encryption scheme. The results show that the proposed watermarking scheme is imperceptible and robust, and suitable for authentication. Similarly, the proposed perceptual encryption scheme outperforms the RHS based scheme in terms of number of operations required to achieve a given level of perceptual encryption and provides control over the amount of perceptual encryption. The overall security of the JPEW has also been evaluated. Additionally, the performance of proposed separate perceptual encryption scheme has been thoroughly evaluated in terms of security and compression efficiency. The scheme is found to be simpler in implementation, have insignificant effect on compression ratios and provide more options for the selection of control factor

Performance analysis of transformation and Bogdonov chaotic substitution based image cryptosystem

In this article, a combined Pseudo Hadamard transformation and modified Bogdonav chaotic generator based image encryption technique is proposed. Pixel position transformation is performed using Pseudo Hadamard transformation and pixel value variation is made using Bogdonav chaotic substitution. Bogdonav chaotic generator produces random sequences and it is observed that very less correlation between the adjacent elements in the sequence. The cipher image obtained from the transformation stage is subjected for substitution using Bogdonav chaotic sequence to break correlation between adjacent pixels. The cipher image is subjected for various security tests under noisy conditions and very high degree of similarity is observed after deciphering process between original and decrypted images