Quantum blind image watermarking with qdct-qim and bb84 key distribution

The protection of multimedia information against copying and tampering attacks by unauthorized parties is a challenge nowadays because of the tremendous increase in digital communications. Based on this, this paper presents a quantum blind image watermarking scheme incorporating Improved Novel Enhanced Representation (INEQR) for efficient image encoding, two-dimensional Quantum Discrete Cosine Transform (QDCT) frequency domain processing, and adaptive QIM for watermark embedding. The selection of watermarking parameters in this framework is carried out in a completely secure manner using Quantum Key Distribution (QKD) based on BB84. Simulation work on 30 standard grayscale images shows the strong imperceptibility, achieving PSNR values in the range of 52–58 dB and SSIM values between 0.98 and 0.999. and a more than 95 percent accuracy level in watermark recovery under attacks such as noise, compression attacks, and geometric attacks, thus authenticating PSNR-52– 58 dB and SSIM-0.98–0.999. Robustness analysis performed against signal processing and geometric attacks indicates reliable extraction of watermarks, where the proposed framework attains an extraction accuracy of more than 95% under additive noise and filtering scenarios and moderate robustness against geometric attacks such as rotation and scaling. These indicate that the proposed framework is effective and provides imperceptible blind image watermarks based on the quantum approach.