Click here to flash read.
With increasing frequency of high-profile privacy breaches in various online
platforms, users are becoming more concerned about their privacy. And
recommender system is the core component of online platforms for providing
personalized service, consequently, its privacy preservation has attracted
great attention. As the gold standard of privacy protection, differential
privacy has been widely adopted to preserve privacy in recommender systems.
However, existing differentially private recommender systems only consider
static and independent interactions, so they cannot apply to sequential
recommendation where behaviors are dynamic and dependent. Meanwhile, little
attention has been paid on the privacy risk of sensitive user features, most of
them only protect user feedbacks. In this work, we propose a novel
DIfferentially Private Sequential recommendation framework with a noisy Graph
Neural Network approach (denoted as DIPSGNN) to address these limitations. To
the best of our knowledge, we are the first to achieve differential privacy in
sequential recommendation with dependent interactions. Specifically, in
DIPSGNN, we first leverage piecewise mechanism to protect sensitive user
features. Then, we innovatively add calibrated noise into aggregation step of
graph neural network based on aggregation perturbation mechanism. And this
noisy graph neural network can protect sequentially dependent interactions and
capture user preferences simultaneously. Extensive experiments demonstrate the
superiority of our method over state-of-the-art differentially private
recommender systems in terms of better balance between privacy and accuracy.
No creative common's license