AccScience Publishing / IJOCTA / Online First / DOI: 10.36922/IJOCTA025480219
RESEARCH ARTICLE

TrustFCL: Task-grained model assessment and aggregation for secure federated continual learning

Xiaoning Wu1 Siqi Du1 Ke Qiu1 Shilin Wen2 Haiting Hou1 Yuxiao Liu1 Jianxin Zhao1 Chi Harold Liu1 Rui Han1*
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1 Department of Computer Science, Beijing Institute of Technology, Beijing, China
2 North Automatic Control Technology Institute, Taiyuan, Shanxi, China
Received: 30 November 2025 | Revised: 13 February 2026 | Accepted: 14 February 2026 | Published online: 28 April 2026
© 2026 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution -Noncommercial 4.0 International License (CC-by the license) ( https://creativecommons.org/licenses/by-nc/4.0/ )
Abstract

Federated learning (FL) enables decentralized model training across devices, while federated continual learning (FCL) continuously adapts to evolving tasks (varying in categories, data distributions, or problem domains). Currently, FL security issues, such as model poisoning and privacy leaks, are undermining trust and reliability, prompting the development of defense methods. However, with evolving tasks, when a poisoning attack occurs, traditional FL defense methods only evaluate whether the latest model from each client is poisoned. Therefore, existing approaches face two limitations: (i) defense methods based on static tasks ensure security by restricting parameter mutations, which undermines the model’s ability to adapt to new tasks and (ii) knowledge preservation mechanisms (e.g., parameters or gradients), crucial for alleviating forgetting, also introduce new vulnerabilities. Poisoned historical knowledge could be reused to launch attacks that are persistent and difficult to trace. To enable secure and adaptive FCL, this paper proposes TrustFCL, which proposes inter-task reliability and task knowledge reliability as both optimization constraints and control feedback. These reliabilities guide both local anti-forgetting training and global decentralized secure aggregation through a dynamic review committee. Furthermore, TrustFCL stores task reliability information on blockchain to prevent tampering and utilizes the consensus mechanism for privacy-preserving model aggregation. Evaluation results show that TrustFCL reduces the accuracy degradation by 37.1% compared to existing defense methods, and achieves a 17.8% improvement over FCL baselines.

Keywords
Federated continual learning
Task-grained aggregation
Distributed optimization
Multi-agent control
Security
Funding
This paper was supported by National Natural Science Foundation of China (Grant No. 62272046, 62132019, 62302039,61872337), and the Special Program for High-Quality Development of the Ministry of Industry and Information Technology (No. CEIEC-20240), a Cooperative Project with the Northern Institute of Automatic Control Technology.
Conflict of interest
The authors declare they have no competing interests.
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