Visually semantic-preserving and people-oriented color image encryption based on cross-plane thumbnail preservation

Uploading images to the cloud has increasingly become a trend, and users have therefore enjoyed many benefits brought by the cloud. On the other hand, these images may carry a wealth of sensitive information, which threatens privacy. Some traditional encryption schemes, in which the original image with rich information is encrypted into the noise-like image, may be able to deal with privacy threats but give up visual usability. Recently, thumbnail-preserving encryption (TPE) was proposed to balance visual usability and privacy but exposes too much information in the encrypted image. Motivated by this, the existing TPE schemes are analyzed in-depth and the scheme to encrypt the image based on cross-plane thumbnail preservation is proposed. A novel architecture of permutation–substitution matching this scheme is constructed, which can preserve the visually semantic information in the encrypted image to balance usability and privacy, and the balance is people-oriented. Meanwhile, a prototype of the scheme is proposed by using a chaotic system, and experiments are conducted using the prototype to verify the excellent performance of this work, e.g., the visual effect is achieved to preserve the semantics, and it becomes the fastest scheme at present om terms of time cost.