Image encryption based on simple shift, permutation and transformation operations on bit layers

Introduction: This paper explores image encryption techniques that leverage transformation, shifting, and permutation operations. The primary focus is on enhancing the security and quality of encrypted raster images by manipulating the individual bit layers of color images. Methods: To encrypt a raster image, the color image is decomposed into binary layers, each representing pixel bits at varying levels of significance. The least significant bits are placed in the least significant layers, while the most significant bits are positioned in the most significant layers. Transformation operations are performed on the bits or their arrays, reconfiguring them into different bit arrangements. Shifting operations are applied to bits across rows and columns within each bit layer, with shifts between layers carried out separately. Additionally, permutation operations are used to further rearrange bit arrays both within individual layers and between layers themselves. Results: Through experimentation, two encryption scenarios have been identified that provide high-quality results for images with different structures. These scenarios produce distinct encrypted images based on the combinations of operations and their sequence, yet maintain a high standard of encryption quality. Conclusions: The proposed method demonstrates an effective approach to encrypting raster images without relying on external encryption tools, minimizing the risk of information loss during decryption. The combination of transformation, shifting, and permutation operations ensures robust encryption, making the technique suitable for a wide range of image types.