Smart contracts have revolutionized the credit landscape. However, their security remains intensely scrutinized due to numerous hacking incidents and inherent logical challenges. One well-known issue is reentrancy vulnerability, exemplified by DAO attacks that lead to substantial economic losses. Previous approaches have employed rule-based and deep learning-based (DL) algorithms to detect and repair reentrancy vulnerability. Large language models (LLM) have been distinguished in recent years for their excellent understanding of text and code. However, less attention has been paid to LLM-based reentrancy vulnerability detection and repair, and direct prompt-based approaches often suffer from inefficiencies and high false positives. To overcome the above shortcomings, this paper proposes a hybrid model framework combining LLM with DL to enhance the detection and repair of reentrancy vulnerabilities. This unified framework comprises three crucial phases: the data processing phase, the vulnerability detection phase, and the vulnerability repair phase. Extensive experimental results validate the superiority of our approach over state-of-the-art baselines, and ablation studies demonstrate the effectiveness of each component. Our approach demonstrates significant improvements in vulnerability detection, with increases of 3.51% in accuracy, 2.31% in recall, 0.42% in precision, and 0.85% in F1-score. Furthermore, our approach can achieve a notable 9.62% enhancement in the repair rate. Finally, we also conducted a user study to emphasize its potential to fortify the security of smart contracts.

Solidity, the dominant smart contract language for Ethereum, has rapidly evolved with frequent version updates to enhance security, functionality, and developer experience. However, these continual changes introduce significant challenges, particularly in compilation errors, code migration, and maintenance. Therefore, we conduct an empirical study to investigate the challenges in the Solidity version evolution and reveal that 81.68 % of examined contracts encounter errors when compiled across different versions, with 86.92 % of compilation errors. To mitigate these challenges, we conducted a systematic evaluation of large language models (LLMs) for resolving Solidity compilation errors during version migrations. Our empirical analysis across both open-source (LLaMA3, DeepSeek) and closedsource (GPT-4o, GPT-3.5-turbo) LLMs reveals that although these models exhibit error repair capabilities, their effectiveness diminishes significantly for semantic-level issues and shows strong dependency on prompt engineering strategies. This underscores the critical need for domain-specific adaptation in developing reliable LLM-based repair systems for smart contracts. Building upon these insights, we introduce SMCFIXER, a novel framework that systematically integrates expert knowledge retrieval with LLM-based repair mechanisms for Solidity compilation error resolution. The architecture comprises three core phases: (1) context-aware code slicing that extracts relevant error information; (2) expert knowledge retrieval from official documentation; and (3) iterative patch generation for Solidity migration. Experimental validation across Solidity version migrations demonstrates our approach's statistically significant 24.24% improvement over baseline GPT-4o on real-world datasets, achieving near-perfect 96.97% accuracy.

Smart contracts are essential for executing computing logic on blockchain networks. However, they are also susceptible to various vulnerabilities. In recent years, the detection of smart contract vulnerabilities has become a significant concern due to the substantial losses caused by hacker attacks. Traditional vulnerability detection approaches rely on expert rules, which often suffer from limitations in accuracy and completeness. Deep learning-based methods offer better coverage of vulnerabilities but may overlook certain vulnerability characteristics and suffer from overfitting during training. In this paper, we propose a novel approach called ConvMHSA-SCVD, which combines knowledge-driven and data-driven algorithms together to detect smart contract vulnerabilities. By incorporating feature selection, data balancing, and a combination of multi-channel convolution and multi-head self-attention neural networks, our ConvMHSA-SCVD achieves effective vulnerability detection in smart contracts. Extensive experiments demonstrate that our approach outperforms the state-of-the-art method in accuracy and F1 score, with improvements ranging from 0.4% to 3.84% and 1.28% to 1.90%, respectively.

At present, the resolution of the most advanced airborne microwave photonic synthetic aperture radar (SAR) can reach the order of centimeters or even millimeters, so the two-dimensional spatial variation and two-dimensional coupling characteristics of motion error will become more serious. In this paper, based on the advantages of nonlinear chirp scaling (NCS) and resampling (RS) processing, a microwave photonic SAR full-aperture autofocus algorithm based on a cascaded NCS-RS is proposed. Firstly, the proposed algorithm combines the typical two-step MoCo and chirp-Z transform (CZT) to correct the range spatial variant characteristics of motion error. Then, a cascaded NCS-RS processing is used to correct the azimuth spatial variant characteristics of motion error, in which NCS processing is introduced before range cell migration correction (RCMC) and RS processing is introduced after RCMC. Finally, the RS in cascaded NCS-RS processing is modified to change with range to correct the range-azimuth coupling characteristic of motion error. The three steps of the algorithm belong to the full-aperture processing, which avoids the problems of grating lobes and image stitching caused by the sub-aperture algorithm. The estimation of the parameters in NCS-RS processing is modeled as a high-dimensional optimization problem. Before solving this optimization problem, it is converted to multiple one-dimensional optimization problems. The results of processing simulated and measured data verify the effectiveness of the proposed algorithm.