PoisonHD: Poison Attack on Brain-Inspired Hyperdimensional Computing

While machine learning (ML) methods especially deep neural networks (DNNs) promise enormous societal and economic benefits, their deployments present daunting challenges due to intensive computational demands and high storage requirements. Brain-inspired hyperdimensional computing (HDC) has recently been introduced as an alternative computational model that mimics the "human brain" at the functionality level. HDC has already demonstrated promising accuracy and efficiency in multiple application domains including healthcare and robotics. However, the robustness and security aspects of HDC has not been systematically investigated and sufficiently examined. Poison attack is a commonly-seen attack on various ML models including DNNs. It injects noises to labels of training data to introduce classification error of ML models. This paper presents PoisonHD, an HDC-specific poison attack framework that maximizes its effectiveness in degrading the classification accuracy by leveraging the internal structural information of HDC models. By applying PoisonHD on three datasets, we show that PoisonHD can cause significantly greater accuracy drop on HDC model than a random label-flipping approach. We further develop a defense mechanism by designing an HDC-based data sanitization that can significantly recover the accuracy loss caused by poison attack. To the best of our knowledge, this is the first paper that studies the poison attack on HDC models.