通过制造梯度分歧提升模型抗攻击能力,无需牺牲正常识别效果。
DRIFT: Divergent Response in Filtered Transformations for Robust Adversarial Defense
- 设计可学习滤波器组,主动打破随机变换中的梯度一致性。
- 在ImageNet上对多种模型有效,抵御白盒、迁移和无梯度攻击。
- 计算开销极低,适合实际部署,为防御提供新原理。
深度神经网络仍易受对抗样本攻击,多数防御在梯度可估计时即失效。我们识别出‘梯度共识’——随机变换导致梯度方向趋同——是攻击可迁移性的关键驱动因素。攻击者利用此共识生成跨变换有效的扰动。本文提出DRIFT(Divergent Response in Filtered Transformations),一种轻量级、可学习的随机滤波器集成,主动破坏梯度共识。与依赖梯度掩蔽的先前方法不同,DRIFT通过最大化雅可比矩阵和输出空间的响应差异,同时保持自然预测准确率,实现梯度异化。贡献有三:(i) 形式化梯度共识并理论分析其与可迁移性的关联;(ii) 提出结合预测一致性、雅可比分离、输出空间分离与鲁棒性的协同训练策略;(iii) 在ImageNet上对CNN和视觉变压器均显著提升鲁棒性,超越现有预处理、对抗训练及扩散模型防御,在自适应白盒、迁移型和无梯度攻击下表现优异。DRIFT仅带来微小运行时与内存开销,确立梯度发散作为实用且通用的防御原则。
原文摘要 · Abstract (English)
Deep neural networks remain highly vulnerable to adversarial examples, and most defenses collapse once gradients can be reliably estimated. We identify \emph{gradient consensus} -- the tendency of randomized transformations to yield aligned gradients -- as a key driver of adversarial transferability. Attackers exploit this consensus to construct perturbations that remain effective across transformations. We introduce \textbf{DRIFT} (Divergent Response in Filtered Transformations), a stochastic ensemble of lightweight, learnable filters trained to actively disrupt gradient consensus. Unlike prior randomized defenses that rely on gradient masking, DRIFT enforces \emph{gradient dissonance} by maximizing divergence in Jacobian- and logit-space responses while preserving natural predictions. Our contributions are threefold: (i) we formalize gradient consensus and provide a theoretical analysis linking consensus to transferability; (ii) we propose a consensus-divergence training strategy combining prediction consistency, Jacobian separation, logit-space separation, and adversarial robustness; and (iii) we show that DRIFT achieves substantial robustness gains on ImageNet across CNNs and Vision Transformers, outperforming state-of-the-art preprocessing, adversarial training, and diffusion-based defenses under adaptive white-box, transfer-based, and gradient-free attacks. DRIFT delivers these improvements with negligible runtime and memory cost, establishing gradient divergence as a practical and generalizable principle for adversarial defense.
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