Atal Chaudhuri

Work place: Department of Computer Science & Engineering, Jadavpur University Kolkata-700032, West Bengal, India



Research Interests: Information Theory, Data Mining, Information Systems, Information Security, Embedded System


Prof. Atal Chaudhuri, B.E., M.E. & PhD from Jadavpur University, West Bengal, India, is working in the Department of Computer Science & Engineering, Jadavpur University, West Bengal, India for last 29 years. His current research interests include: embedded system, cryptography, information sharing, steganography, watermarking and data mining.

Author Articles
An Improved DCT based Image Watermarking Robust Against JPEG Compression and Other Attacks

By Soumik Das Monalisa Banerjee Atal Chaudhuri

DOI:, Pub. Date: 8 Sep. 2017

Rapid growth of internet service attains better security of multimedia contents now a days. Heading this problem a DCT-based color image watermarking framework is proposed in this article. Many earlier works have suggested embedding watermark information in the low frequencies of the image to enhance the robustness against JPEG compression because low frequencies hold the most significant information of the image and not affected significantly by the quantization method of JPEG algorithm. Replacement of low-frequency components with watermark directly may incur undesirable degradation to the image quality. To preserve the visual quality of watermarked images, we are proposing a watermarking framework that adjusts the DCT low-frequency coefficients by scaled averaging. The security issue is well-taken care with double secret keys. Experimental result set demonstrates that the embedded watermark can be extracted efficiently from the JPEG-compressed images even after very high compression, re-watermarking, other image processing attacks. The extraction algorithm is blind i.e., neither host image nor the watermark is needed at the time of extraction.

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A Secure Symmetric Image Encryption Based on Bit-wise Operation

By Prabir Kr. Naskar Atal Chaudhuri

DOI:, Pub. Date: 8 Jan. 2014

This paper shows a symmetric image encryption based on bit-wise operation (XORing and Shifting). The basic idea is block ciphering (size of each block is 4 bytes) technique to cipher the secret bytes, after that ciphered bytes are again shuffled among N positions (N is the size of secret file). The scheme is combination of substitution as well as transposition techniques which provides additional protection of the secret data. The substitution and transposition are done using dynamic substitution box (SBOX) and transposition box (TBOX) which are generated using the secret key and made to vary for each block during ciphering. The size of encrypted data is same as the size of secret data and the proposed scheme has been tested using different images. We have also presented the security analysis such as key sensitivity analysis, statistical analysis, and differential analysis to prove the strength of our algorithm against crypto analysis.

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Other Articles