Thumbnail Preserving Encryption

In this paper we motivate the need for image encryption techniques which preserve certain visual features of images (and hide all other information), to provide a balance between privacy and usability in the context of cloud-based image storage services. In particular, we introduce the concept of ideal or exact Thumbnail-Preserving Encryption (TPE), a special case of format-preserving encryption, and present a concrete construction. In TPE, a ciphertext is itself an image that has the same thumbnail as the plaintext (unencrypted) image, but that provably leaks nothing about the plaintext beyond its thumbnail. We provide a formal security analysis for the construction, and a prototype implementation to demonstrate compatibility with existing services. We also study the ability of users to distinguish between thumbnail images preserved by TPE. Our findings indicate that TPE is a realistic and promising way to balance usability and privacy concerns for images.

Published at NDSS 2019.

You can access the full paper here

You can find the source of the web plugin implementation on Github