Tamper Localization Through Fragile Watermarking with Vigenère Cipher Encryption

The primary objective of this paper is to detect and locate alterations in digital images to ensure their tamper-proofing. To achieve this, a fragile watermarking technique has been employed and the obtained watermark has been encrypted using the Vigenère Cipher/Playfair. This versatile technique can be applied to both grayscale and colour images, focusing on spatial domain watermarking. In the proposed approach, replace the Least Significant Bits (LSBs) of the host image's pixels have been replaced with the encrypted watermark data. Authentication involves extracting the watermark from the watermarked image and comparing it with the original watermark. This Python-based implementation of Fragile Watermarking is subjected to various typical attacks on watermarked images to assess its performance. Experimental results demonstrate that the watermarked images show PSNR over 55 dB, and SSIM over 0.99 for a standard set of images, indicating the method's effectiveness in detecting image integrity in the presence of these attacks.