A Note on "Confidentiality-Preserving Image Search: A Comparative Study Between Homomorphic Encryption and Distance-Preserving Randomization"

TL;DR

This paper critically examines two recent image search schemes based on encryption methods, identifying flaws and suggesting improvements for efficiency and correctness in privacy-preserving image search.

Contribution

The paper provides a detailed critique of existing schemes, clarifies misconceptions about homomorphic encryption use, and proposes more efficient alternatives.

Findings

The first scheme does not utilize the homomorphic property as claimed.

The second scheme's encryption can be replaced with symmetric key encryption.

Both schemes have significant flaws that compromise their effectiveness.

Abstract

Recently, Lu et al. have proposed two image search schemes based on additive homomorphic encryption [IEEE Access, 2 (2014), 125-141]. We remark that both two schemes are flawed because: (1) the first scheme does not make use of the additive homomorphic property at all; (2) the additive homomorphic encryption in the second scheme is unnecessary and can be replaced by a more efficient symmetric key encryption.