Machine learning models based on artificial neural networks have been widely adopted to support diverse complex applications. However, the training of such models heavily relies on large-scale datasets, which may raise privacy concerns. Taking the Internet of Things (IoT) as an example, distributed edge devices collect data, while central servers aggregate this data for model training and in-depth analysis. Unlike frameworks like federated learning, local model training becomes infeasible due to constrained edge device capabilities, model confidentiality requirements, or the separation of complete data features across multiple devices. This scenario may render traditional federated learning-based privacy-preserving frameworks ineffective. To address these limitations, we propose an efficient privacy-preserving model training protocol that demonstrates practical advantages over fully homomorphic encryption and functional encryption methods. Our protocol leverages additively homomorphic encryption combined with the Chinese Remainder Theorem to design secure matrix-vector computations, minimizing encryption/decryption operations and reducing computational overhead on edge devices while preserving training efficiency and model accuracy. To further optimize performance, we further propose a secondary protocol that introduces optimization strategies to enhance efficiency and lighten edge nodes’ computational burdens. Security analysis and rigorous correctness proofs are provided, and performance evaluations and experimental validation confirm both protocols’ practical feasibility and effectiveness.

Among various blockchain applications, decentralized anonymous payment (DAP) systems stand out for their enhanced privacy protection compared to traditional payment methods. However, DAPs face challenges such as the lack of asset recovery and identity verification features. To ensure the long-term healthy development of DAP systems, adherence to legal regulations and privacy protection is equally critical. In response to these requirements, we propose a$\textsf {CR}$-$\textsf {DAP}$system that offers a secure and efficient solution without compromising on practicality. Our innovation lies in introducing an identity-based traceable anonymous signature scheme, which skillfully balances anonymity with traceability. This scheme supports private key retrieval and allows for identity tracking when necessary, addressing key pain points in existing anonymous payment systems and enhancing user trust. We have implemented the prototype of this signature scheme and the$\textsf {CR}$-$\textsf {DAP}$system, evaluating its performance to demonstrate its practicality.

Thyroid cancer is the most pervasive disease in the endocrine system and is getting extensive attention. The most prevalent method for an early check is ultrasound examination. Traditional research mainly concentrates on promoting the performance of processing a single ultrasound image using deep learning. However, the complex situation of patients and nodules often makes the model dissatisfactory in terms of accuracy and generalization. Imitating the diagnosis process in reality, a practical diagnosis-oriented computer-aided diagnosis (CAD) framework towards thyroid nodules is proposed, using collaborative deep learning and reinforcement learning. Under the framework, the deep learning model is trained collaboratively with multiparty data; afterward classification results are fused by a reinforcement learning agent to decide the final diagnosis result. Within the architecture, multiparty collaborative learning with privacy-preserving on large-scale medical data brings robustness and generalization, and diagnostic information is modeled as a Markov decision process (MDP) to get final precise diagnosis results. Moreover, the framework is scalable and capable of containing more diagnostic information and multiple sources to pursue a precise diagnosis. A practical dataset of two thousand thyroid ultrasound images is collected and labeled for collaborative training on classification tasks. The simulated experiments have shown the advancement of the framework in promising performance.

While blockchain is known to support open and transparent data exchange, partly due to its nontamperability property, it can also be (ab)used to facilitate the spreading of fake and misleading information or information that was subsequently discredited. Hence, this paper proposes a practical, redactable blockchain framework with a public trapdoor (hereafter referred to as PRBFPT). PRBFPT comprises an editing scheme for adding blocks using a new type of blockchain with a chameleon hash. Specifically, PRBFPT is able to involve all nodes in the blockchain in the editing operations by means of a public trapdoor, without requiring additional trapdoor management by predefined nodes or organizations. PRBFPT is also designed to audit and record the content of each editing operation. In other words, after editing and deleting the original data, PRBFPT can still verify its legitimacy. We also propose a contract-based locked voting scheme to better support voting. We then evaluate the prototype implementation of PRBFPT, whose findings show that the total time consumption of adding modules is at the millisecond level, with a negligible impact on the performance of the original system. In addition, the evaluation findings show that the cost of initiating the special transactions is comparable to the consumption of normal Ethereum transactions and is within a manageable range.

In our data-centric society, major service providers have access to vast amounts of user information (e.g., user-generated content such as social media posts, and device-generated content such as geolocation data) for convenient and efficient services. There are privacy implications when users authorize share personal data managed by service providers. To make authorization private and controllable, in this paper, we propose a private authorization scheme oriented service providers. A decentralized publicly-verifiable re-encryption method based on IPFS is proposed to minimize the reliance on service providers, by shifting to a distributed storage and computation model. Besides, we propose a trustless authorization authentication method that hides the authorization relationship to protect user privacy. We also evaluate the security of our scheme, as well as its performance to demonstrate utility.

Medical data sharing can improve the quality of medical care and promote progress in the field of public health. However, medical data has high confidentiality and complexity. Taking the clinical diagnosis and treatment data of Diabetes Mellitus Type 2 (T2DM) in medical treatment as an example, T2DM data often has the phenomenon of "multi-disease coexistence" and is insecure and inaccurate in the process of sharing. Based on Blockchain and Attribute- Encryption (ABE), we propose a T2DM data sharing system to solve the above problems. An Attribute-Encryption algorithm T2DM-CP-ABE is proposed to solve the problem of excessive sharing granularity. T2DM-CP-ABE, combined with the medical data contribution module, takes the contribution factor as an important consideration, to stimulate the power of T2DM data sharing and promote the development of national diabetes prevention. Based on the Blockchain, a medical data attribute authorization model is proposed, which provides a credible solution for multiple hospitals to realize medical data attribute authorization, and realizes the clinical diagnosis and treatment data sharing of T2DM among doctors. Based on Blockchain and ABE technology, a data sharing system for T2DM has been implemented on the Fabric platform. The result shows that the average time for the system to complete a single sharing is less than 1 second.

The phenomenon of unbalanced regional medical resources has led to large differences in the implementation experience of clinical pathways in hospitals with different medical levels. However, due to the fear of privacy leakage and the lack of sharing motivation, there is a lack of effective collaborative communication channels for clinical pathways among medical institutions. In response to these problems, we propose a blockchain-based sharing incentive scheme for clinical pathway experience, which uses the clinical pathway implementation effect evaluation system to evaluate the quality of clinical pathway experience data. Specifically, we designe a two-phase cross-domain shared transaction model for the transaction of clinical pathway experience data. Moreover, we introduce the shared transaction alliance committee to verify and review the transaction, and solve the problems in the transaction in the arbitration phase. Finally, the functional test results show that the system meets the experience sharing incentive requirements, and the performance test results show that the TPS of sharing clinical pathway experience read and writed can reach around 600 and 1000, and the transaction latency of each phase is within 3 s.