arXiv subjects

Lingyue Qin

Publications and source records attributed to Lingyue Qin.

3 recordsLinked to original sources

arXiv2026

Algebraic Cryptanalytic Extraction on Hard-Label Neural Networks

Although the state-of-the-art model extraction attack on the hard-label Fully-connected Neural Network (FCN) by Carlini et al. at EUROCRYPT 2025 has polynomial-time complexity in theory, its dual-point clustering relies on singular value decomposition (SVD) with a time complexity of $\mathcal{O}(n^2 (d^{(k)})^3)$, resulting in huge runtime in practice. To address this computational bottleneck, this work transforms Carlini et al.'s geometric-view hard-label attack into an algebraic framework, and proposes two efficient clustering methods: Normal Rank Check (NRC) and Approximate Signature Vector (ASV). The NRC and ASV methods replace Carlini et al.'s heavy SVD-based rank checking with simple rank checking or inner-product operations, reducing the clustering complexity to $\mathcal{O}(n (d^{(k)})^3)$ on average. Furthermore, this paper presents the first model extraction attack against hard-label max-pooling Convolutional Neural Networks (CNNs) by combining the ASV method with the kernel-centric clustering scheme instead of the neuron-centric clustering, which fully exploits the property of weight sharing in convolutions and fills a cryptanalysis gap. Experiments on FCNs and the max-pooling LeNet-5 demonstrate that our NRC/ASV methods drastically cut clustering time, and improve the overall efficiency in the model extraction.

cs.CR↗

arXiv2026

Normal Alignment: Improved Cryptanalytic Sign Recovery on Hard-Label Networks

At EUROCRYPT 2025, Carlini et al. proposed a breakthrough in the cryptanalytic extraction on hard-label (S1) deep neural networks (DNNs), demonstrating polynomial-time signature and sign recovery. However, Carlini et al.'s sign-recovery method (which we call Future Toggle) suffers only a marginal advantage over random guessing, producing high-confidence wrong sign predictions in deeper layers. Such errors trigger expensive exponential-time enumeration. This work presents Normal Alignment, a novel statistical sign-recovery approach for S1 DNNs. Drawing on the expected length difference between projected normals of adjacent decision facets at dual points, our method infers neuron signs via normal-signature alignment. It delivers higher voting accuracy and pushes erroneous predictions to low-confidence ranks, which further enables a more efficient combined method, eSOE + Alignment, by combining Normal Alignment with the hard-label SOE extension. This combined strategy removes heavy enumeration overhead and realizes exact polynomial-time full sign recovery. Experiments demonstrate the effectiveness of our method, especially for deep layers. For example, with our method, the signs for CIFAR-10 (architecture 192-64$\times$8-10) and MNIST (architecture 64-96$\times$3-32-10) models can be fully recovered in polynomial time; in contrast, Carlini et al.'s sign-recovery method would require exponential-time enumerations involving $2^{52}$ or $2^{82}$ guesses of the signs, respectively.

cs.CR↗

arXiv2026

Algebraic Attack on Convolutional Neural Networks with Max Pooling

Recovering the weights and biases of deep neural networks (DNNs) via black-box input-output queries, known as parameter extraction attacks, has been extensively studied for ReLU-based fully connected neural networks (FCNNs), but remains unexplored for convolutional neural networks (CNNs) with the max pooling function, a core architecture for computer vision and multimedia processing. The key challenge lies in the CNN max pooling layer, which introduces an additional non-linearity and hides ReLU critical points, rendering existing FCNN extraction methods inapplicable. To address this gap, we propose the first cryptanalytic extraction attack tailored for CNNs with the max pooling function. First, we establish an algebraic representation of CNNs, formally proving that CNNs are piecewise linear functions enabling the extension of linearity-based extraction principles. We then identify two novel types of critical points in CNNs: ReLU-Pooling Critical Points (RPCPs) and Pooling Switching Points (PSPs). We design complementary extraction techniques: a pattern matching method for RPCPs to recover partial signatures and signs, and an internal differential extraction attack for PSPs, inspired by cryptographic internal differential analysis, to recover high-accuracy signatures. Given that PSPs are far more abundant than RPCPs and yield a highly efficient extraction method, and that RPCPs are indispensable for bias recovery, we integrate both methods: the PSP method enables efficient signature extraction, while a single RPCP recovers the sign and bias. We evaluate our attack on multiple CNN architectures, including modern adaptations of LeNet-5, trained on random data, MNIST, and CIFAR-10. Experimental results demonstrate that our approach achieves high extraction accuracy with polynomial query complexity and runtime, even for deep CNN layers. This work fills a research gap in CNN security.

cs.CR↗