A batch image encryption scheme based on chaining random grids

Taking batch image encryption into account, the existing single-image encryption schemes suffer from either high computational cost or image size expansion, which worsens when it is a batch of images to encrypt. This paper proposes a novel encryption scheme based on chaining random grids, suitable for dealing with batch binary, grey-level, and color images. Compared with the existing random- grid-based encryption schemes, our method encoded m images into m C 1 total random cipher-grids, rather than 2m cipher-grids encoded by existing encryption schemes. The decryption process is done by a human visual system and no computation is required. This method requires neither extra pixel expansion nor any encoding basis matrix, which are required and unavoidable for accustomed visual cryptography. Structured analysis and discussion about quality and secrets are performed, and the effectiveness of the method is shown in experimental results.