K.B. Shiva Kumar

Abstract Nanocrystalline ZnO is an effective heterogeneous catalyst for the [2+3]‐cycloaddition of sodium azide with nitriles to afford 5‐substituted 1 H ‐tetrazoles in good yields.

Data interchange through internet becomes an eminent technique and hence data security has become a big challenge in the field of communication with the increased use of internet. Demand for data authentication and effective means to control data integrity has been steadily increasing. Such a demand is due to the ease with which digital data can be tampered. Thus, cryptography and watermarking can be replaced with steganography for secure data communication and data privacy. In this paper, the carrier image is selected such that the payload/secret image and least significant bits of carrier image are matched with larger degree of compatibility and the hiding process introduces negligible changes in the resulted stego image based on genetic algorithm. In the proposed method we have achieved 30 to 40% improvements in the performance when compared to different existing methods. Selection of a suitable cover image and hiding the secret data to enhance the imperceptibility is a very challenging task. Genetic algorithm is used to ease the work of exploring an impossible task of selection from the trillions and millions of combinations.

The important issue of modern communication is establishing secret communication while using public channel and is achieved by steganography. In this paper, we propose Coherent Steganographic Technique using Segmentation and Discrete Cosine Transform (CSSDCT). The cover image is divided into 8*8 blocks and DCT is applied on each block. The number of payload MSB bits is embedded into DCT coefficients of the cover image coherently based on the values of DCT coefficients. It is observed that the proposed algorithm has better PSNR, Security and capacity compared to the existing techniques.

Offline signature verification system finds several applications in monitory transaction systems like banks. However one of the major challenges in this direction is the capability of the system to detect skilled and unskilled forgery. Many cases of bank check forgeries have been reported. Most of the offline signature verification system adopts recognition based technique where the system classifies a given signature sample as one of the samples from the database. However detection of a forgery in a given sample is challenging as the input sample looks similar to one of the samples in the database. In this paper we propose an innovative approach for offline signature verification with polar feature descriptor for signature that contains Radon Transform and Zernike Moments. Verification is performed using Multiclass Support Vector Machine. Once a signature is verified as being of a registered class, PLS Regression is applied on the sample against all samples in the database of the verified user to obtain regression score. Log Likelihood of the sample against all sample of the user is calculated using Hidden Markov Model. Authenticity of the classification is justified if the regression score and Log Likelihood distance deviation is less than 5%. Results show that the system verifies signature with an accuracy of 98% with false acceptance rate of .8%. Proposed system also detects skilled forgery with an accuracy of 71% and Random forgery with an accuracy of 76%.

Steganography enables to have a secret communication in modern information technology using public channel. In this paper, we propose Dual Transform Technique for Robust Steganography (DTTRS). The cover image is segmented into blocks of 4*4 each and Discrete Wavelet Transform (DWT) is applied on each block. In the resulting DWT coefficients, blocks of vertical band of 2*2 each are considered and Integer Wavelet Transform (IWT) is applied to get blocks of 1*1 each. The IWT is applied on vertical band of DWT of payload to generate coefficients of payload and are embedded into IWT coefficients of cover image using least significant bit replacement method. On applying IIWT and IDWT, stego image is derived. The concept of error detecting and correcting coding technique is employed to ensure more reliable communication. It is observed that the proposed algorithm has excellent PSNR, provides high level security and more robust compared to individual transform techniques.