V. H. Mankar

SVD and Error Control Coding Based Digital Image Watermarking

Digital media is a craze these days. With the present day internet connectivity the world has become smaller. The copyright protections of intellectual properties have become a necessity for prevention of illegal copying and content integrity verification. Newer data hiding techniques that satisfy the requirements of imperceptibility, robustness, capacity, or data hiding rate and security of the hidden data etc. are being developed. Therefore the preference to go for digital image watermarking, to show resiliency against various unintentional or deliberate attacks has increased. Watermarking is a method of data authentication by embedding a watermark in image characteristics with expectation. Here in this work, this is done using a mathematical tool called the singular value decomposition (SVD). Earlier SVD had been used individually, as a tool for watermarking of digital media, but this work incorporates error control coding to it, by a novel zig-zag scan operation on pixels done before coding, thereby increasing the robustness. This work here by focuses on using both of them together to provide a robust technique developed for protection of the intellectual property against the popular malicious attacks. The algorithm is later applied and tested on the standard checkmark techniques practically by attacking the watermarked image against standard simulated attacks and recovering the watermarked logo from it.

Text Encryption Algorithms based on Pseudo Random Number Generator

paper presents algorithms for encryption and decryption developed using pseudo random number generator (PRNG) and non-Linear functions. PRNG used in the work are matlab random number generator (RNG) and Linear congruential generator (LCG). The developed algorithms are named according to PRNG used in it. State of PRNG is considered as secret key of the cipher. The encryption schemes have been cryptanalyzed for four different methods to test its strength like key space analysis, plaintext and key sensitive test. Known plaintext attack is also performed by taking into consideration a small string of plaintext and the complete cipher text for small text. The analysis is performed on different keys selected randomly from key space for various texts and files. Key sensitivity up to 50 % and plaintext sensitivity ranging from 3% to 50 % have been obtained in the developed ciphers. It is concluded that proposed encryption algorithms have strength against linear, differential and statistical attacks. Keywordsyptography, Pseudo random number generator (PRNG), Random number generator, Linear Congruential Generator.

SVD and Neural Network Based Watermarking Scheme

Presently the WWW phenomenon has brought the world in to the personal computer. Digital media is thereby given high priority. But this has increased the frequency of security breach of intellectual properties. Therefore copyright protections and content integrity verification are highly recommended. What we need is newer data hiding techniques that must be imperceptible, robust, highly secured, etc. Digital image watermarking is one of the ways that is resilient to various attacks on the image based digital media where data authentication is done by embedding of a watermark in image characteristics. This work incorporates singular value decomposition (SVD) based image watermarking. Here unlike previous work done by researchers, error control coding (ECC) and artificial neural networks (ANN) for the authentication purposes have been used. ECC and ANN increase the robustness of the method against malicious attacks.

Robust Image Watermarking Under Pixel Wise Masking Framework

The current paper presents a robust watermarking method for still images, which uses the similarity of discrete wavelet transform and human visual system (HVS). The proposed scheme makes the use of pixel wise masking in order to make binary watermark imperceptible to the HVS. The watermark is embedded in the perceptually significant, spatially selected detail coefficients using sub band adaptive threshold scheme. The threshold is computed based on the statistical analysis of the wavelet coefficients. The watermark is embedded several times to achieve better robustness. Here, a new type of non-oblivious detection method is proposed. The improvement in robustness performance against different types of deliberate and non-intentional image impairments (lossy compression, scaling, cropping, filtering etc) is supported through experimental results. The reported result also shows improvement in visual and statistical invisibility of the hidden data. The proposed method is compared with a state of the art frequency based watermarking technique, highlighting its performance. This algorithmic architecture utilizes the existing allocated bandwidth in the data transmission channel in a more efficient manner.

Chaotic Cipher Using Arnolds and Duffings Map

This paper deals with the application of concept of identifiability based on output equality approach on chaotic ciphers developed using 2-D chaotic maps, Duffings and Arnolds Cat map and they are named as Duffings and Arnold’s Cat, according to the map used. Due to the less key space generally many chaotic cryptosystem developed are found to be weak against Brute force attack which is an essential issue to be solved. Thus, concept of identifiability proved to be a necessary condition to be fulfilled by the designed chaotic cipher to resist brute force attack, which is an exhaustive search. As 2-D chaotic maps provide more key space than 1-D maps thus they are considered to be more suitable. This work is accompanied with analysis results obtained from these developed cipher. Moreover, identifiable keys are searched for different input texts at various key values. The ciphers are also analyzed for plaintext sensitivity and key sensitivity for its validity to provide security.

An Angle QIM Watermarking in STDM Framework Robust against Amplitude Scaling Distortions

Quantization index modulation (QIM) watermarking proposed by Chen and Wornell provides computational efficient blind watermarking based on Costa’s dirty paper codes. The limitation of this is its vulnerability against amplitude scaling distortion. The present work is proposed to solve this problem based on angle QIM within spread transform dither modulation (STDM) framework. AQIM embeds the information by quantizing the angle formed by the host-signal vector with respect to the origin of a hyperspherical coordinate system as opposed to quantizing the amplitude of pixel values. It has been shown experimentally that the proposed work not only provides the resistance against this valumetric scaling distortion but also against non-linear, gamma correction and constant luminance change.

A Chaotic Encryption Algorithm: Robustness against Brute-Force Attack

An encryption method is proposed that uses self-invertible matrix, modular function, Non-Linear shift register and the chaotic map known as Logistic. Parameter of Logistic map act as secret key. As chaotic system used in this algorithm is 1-D system, the key space is lesser than 2100 which shows that the method is weak against Brute-force attack but identifiability property of the selected key from key space assures its strength against the attack. Key sensitivity and plaintext sensitivity of the key chosen from key space for the algorithm is analyzed and its strength against known-plaintext attack is also tested and conclusions are derived.