Hiding from Facebook: An Encryption Protocol resistant to Correlation Attacks

TL;DR

This paper introduces an encryption protocol for social network images that minimizes correlation between encrypted face tags, enhancing privacy against correlation attacks, and includes a key distribution scheme for trusted group decoding.

Contribution

The paper proposes a novel coding system that reduces correlation in encrypted face tags and a key distribution method enabling trusted group decoding.

Findings

Encryption reduces correlation between face instances

Key distribution allows trusted group access

Enhances privacy against correlation attacks

Abstract

In many social networks, one publishes information that one wants to reveal (e.g., the photograph of some friends) together with information that may lead to privacy breaches (e.g., the name of these people). One might want to hide this sensitive information by encrypting it and sharing the decryption key only with trusted people, but this might not be enough. If the cipher associated to a face is always the same, correlation between the output of a face recognition system and the cipher can give useful clues and help train recognizers to identify untagged instances of the face. We refer to these as "correlation attacks". In this paper we present a coding system that attempts to counter correlation attacks by associating to each instance of a face a different encryption of the same tag in such a way that the correlation between different instances is minimal. In addition, we present a key distribution code that allows only the owner of the images to encode the tags, but allows a group of trusted friends to decode them.