  We propose an image identification scheme for double-compressed encrypted
JPEG images that aims to identify encrypted JPEG images that are generated from
an original JPEG image. To store images without any visual sensitive
information on photo sharing services, encrypted JPEG images are generated by
using a block-scrambling-based encryption method that has been proposed for
Encryption-then-Compression systems with JPEG compression. In addition, feature
vectors robust against JPEG compression are extracted from encrypted JPEG
images. The use of the image encryption and feature vectors allows us to
identify encrypted images recompressed multiple times. Moreover, the proposed
scheme is designed to identify images re-encrypted with different keys. The
results of a simulation show that the identification performance of the scheme
is high even when images are recompressed and re-encrypted.
