Rethinking Non-idealities in Memristive Crossbars for Adversarial Robustness in Neural Networks
Deep Neural Networks (DNNs) have been shown to be prone to adversarial attacks. With a growing need to enable intelligence in embedded devices in this Internet of Things (IoT) era, secure hardware implementation of DNNs has become imperative. Memristive crossbars, being able to perform Matrix-Vector-Multiplications (MVMs) efficiently, are used to realize DNNs on hardware. However, crossbar non-idealities have always been devalued since they cause errors in performing MVMs, leading to degradation in the accuracy of the DNNs. Several software-based adversarial defenses have been proposed in the past to make DNNs adversarially robust. However, no previous work has demonstrated the advantage conferred by the non-idealities present in analog crossbars in terms of adversarial robustness. In this work, we show that the intrinsic hardware variations manifested through crossbar non-idealities yield adversarial robustness to the mapped DNNs without any additional optimization. We evaluate resilience of state-of-the-art DNNs (VGG8 & VGG16 networks) using benchmark datasets (CIFAR-10 & CIFAR-100) across various crossbar sizes towards both hardware and software adversarial attacks. We find that crossbar non-idealities unleash greater adversarial robustness (>10-20%) in DNNs than baseline software DNNs. We further assess the performance of our approach with other state-of-the-art efficiency-driven adversarial defenses and find that our approach performs significantly well in terms of reducing adversarial losses.
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