Paper 2019/295

Balancing Image Privacy and Usability with Thumbnail-Preserving Encryption

Kimia Tajik, Akshith Gunasekaran, Rhea Dutta, Brandon Ellis, Rakesh B. Bobba, Mike Rosulek, Charles V. Wright, and Wu-chi Feng


In this paper, we motivate the need for image encryption techniques that preserve certain visual features in images and hide all other information, to balance 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 an efficient and promising approach to balance usability and privacy concerns for images. Our code and a demo are available at

Available format(s)
Publication info
Published elsewhere. Minor revision. NDSS 2019
Thumbnail-preserving image encryptionFormat-preserving encryptionImage privacyUsability
Contact author(s)
tajikk @ oregonstate edu
2019-03-20: received
Short URL
Creative Commons Attribution


      author = {Kimia Tajik and Akshith Gunasekaran and Rhea Dutta and Brandon Ellis and Rakesh B.  Bobba and Mike Rosulek and Charles V.  Wright and Wu-chi Feng},
      title = {Balancing Image Privacy and Usability with Thumbnail-Preserving Encryption},
      howpublished = {Cryptology ePrint Archive, Paper 2019/295},
      year = {2019},
      doi = {10.14722/ndss.2019.23432},
      note = {\url{}},
      url = {}
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