Explainable AI-Based Real-Time Hybrid System for Blockchain Anomaly Detection: A Multi-Cryptocurrency Perspective

(1) * Amira Hamdi Shabaan Mail (collage of computing, AASTMT, Egypt)
(2) Saleh Mesbah Elkaffa Mail (College of Computing and Information Technology, Arab Academy for Science, Technology, and Maritime Transport (AASTMT), Alexandria, Egypt)
(3) Gamal Abd El-Nasser A. Said Mail (College of Computing and Information Technology, Arab Academy for Science, Technology, and Maritime Transport (AASTMT), Alexandria, Egypt)
(4) Ossama Mohamed Badawy Mail (Port Training Institute, AASTMT, Alexandria,, Egypt)
*corresponding author

Abstract


This study achieves a 5% improvement in AUC-ROC and a 2.5% increase in recall compared to state-of-the-art anomaly detection methods in blockchain networks. Blockchain technologies have rapidly evolved, offering transparency and security across decentralized systems. However, detecting anomalies and fraudulent activities remains a significant challenge. This research proposes a unified hybrid framework integrating Graph Neural Networks (GNNs), Transformers, and XGBoost within a federated learning environment for real-time anomaly detection in multi-cryptocurrency blockchain networks. Unlike previous works, this model employs explainable AI (XAI) methods (SHAP and LIME) to enhance interpretability and trust. The framework utilizes PSO-based hyperparameter optimization, reducing convergence time by 20%. Experimental evaluations on benchmark datasets (Elliptic, Bitcoin-OTC, and Ethereum) demonstrate superior performance in precision, recall, and FPR compared to CARE-GNN and GeniePath. The results confirm the proposed model’s scalability, transparency, and real-time efficiency, making it suitable for deployment in high-frequency blockchain monitoring systems.

  


Keywords


Blockchain; Anomaly Detection; Explainable Artificial Intelligence (XAI); Graph Neural Network (GNN); Transformer; XGBoost; Federated Learning; Particle Swarm Optimization (PSO); Cryptocurrency; Fraud Detection

   

DOI

https://doi.org/10.29099/ijair.v9i2.1571
      

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References


S. Shukla, K. Bisht, K. Tiwari, and S. Bashir, “Comparative Study of the Global Data Economy”, In Proc. of the Data Economy in the Digital Age, PP. 63–86, 2023. (DOI: 10.1007/978-981-99-7677-5_4).

M. Akour, and M. Alenezi, “Higher Education Future in the Era of Digital Transformation”, Education Sciences, Vol. 12, PP. 784, 2022. (DOI: 10.3390/educsci12110784).

N. Chipangamate, and G. Nwaila, “Assessing Challenges and Strategies for Driving Energy Transitions in Emerging Markets: A Socio-Technological Systems Perspective”, International Journal of the Energy Geoscience, PP. 100257, 2023. (DOI: 10.1016/j.engeos.2023.100257).

M. Jamshidi, A. Dehghaniyan-Serej, A. Jamshidi, and O. Moztarzadeh, “The Meta-Metaverse: Ideation and Future Directions”. International Journal of the Future Internet, Vol. 15, PP. 252, 2023. (DOI: 10.3390/fi15080252).

I. Chatzopoulou, P. Tsoutsa, and P. Fitsilis, “How Metaverse is Affecting Smart Cities Economy”, In Proc. of the 27th Pan-Hellenic Conf. on Progress in Computing and Informatics, PP. 254–259, 2023.

H. Chen, H. Duan, M. Abdallah, Y. Zhu, Y. Wen, A. Saddik, and W. Cai, “Web3 Metaverse: State-of-the-Art and Vision”. International Journal of ACM Transactions on Multimedia Computing, Communications, and Applications, Vol. 20, PP. 1–42, 2023. (DOI:10.1145/3630258)

M. Aljanabi, and S. Mohammed, “Metaverse: Open Possibilities”, International Journal of Iraqi for Computer Science and Mathematics, Vol. 4, PP. 79–86, 2023. (DOI: 10.52866/ijcsm.. 2023.02.03.007).

Y. Ajani, R. Enakrire, B. Oladokun, and M. Bashorun, “Reincarnation of libraries via Metaverse: A Pathway for a Sustainable Knowledge System in the Digital Age”. Business Information Review, Vol. 40, PP. 191– 197, 2023. (DOI: 10.1177/02663821231208044).

A. Koohang, J. Nord, K. Ooi, G. Tan, M. Al-Emran, A. Baabdullah, D. Buhalis, T. Cham, C. Dennis, “Shaping the Metaverse into Reality: A Holistic Multidisciplinary Understanding of Opportunities, Challenges, and Avenues for Future Investigation”, International Journal of Computer Information Systems, Vol. 63, PP. 735–765, 2023. (DOI: 10.1080/08874417.2023.2165197).

A. Abdelmaboud, A. Ahmed, M. Abaker, M. Eisa, H. Albasheer, S. Ghorashi, and F. Karim, “Blockchain for IoT Applications: Taxonomy, Platforms, Recent Advances, Challenges, and Future Research Directions”, In Proc. of the Electronics, Vol. 11, PP. 630, 2022. (DOI: 10.3390/electronics11040630).

M. Oladejo, “Blockchain Technology: Disruptor or Enhancer to the Accounting and Auditing Profession”, 2023.

D. Mourtzis, “The Metaverse in Industry 5.0: A Human-Centric Approach towards Personalized Value Creation”, International Journal of the Encyclopedia, Vol. 3, PP. 1105–1120, 2023. (DOI: 10.3390/encyclopedia3030080).

H. Allioui, and Y. Mourdi, “Exploring the Full Potentials of IoT for Better Financial Growth and Stability: A Comprehensive Survey”, Sensors, Vol. 23, PP. 8015, 2023. (DOI: 10.3390/s23198015).

A. Grech, “Young people & information. A Manifesto”, International Journal of the 3CL Foundation, 2023.

M. Jones, “Digital Authoritarianism in the Middle East: Deception, Disinformation, and Social Media”, International Journal of Hurst Publishers, 2022.

N. Kyriazis, “Is Bitcoin Similar to Gold? An Integrated Overview of Empirical Findings”. International Journal of Risk and Financial Management, Vol. 13, PP. 88, 2020. (DOI: 10.3390/jrfm13050088).

I. Din, K. Awan, A. Almogren, and J. Rodrigues, “Integration of IoT and Blockchain for Decentralized Management and Ownership in the Metaverse”. International Journal of Communication Systems, Vol. 36, 2023. (DOI: 10.1002/dac.5612).

N. Bao, J. Nakazato, A. Muhammad, E. Javanmardi, and M. Tsukada, “Towards a Trusted Inter-Reality: Exploring System Architectures for Digital Identification”. In Proc. of the 13th International Conf. on the Internet of Things, PP. 270–275, 2023.

T. Huynh-The, Q. Pham, X. Pham, T. Nguyen, Z. Han, and D. Kim, “Artificial Intelligence for the Metaverse: A Survey of Engineering Applications of Artificial Intelligence”, Vol. 117, PP. 105581, 2023. (DOI: 10.1016/j.engappai.2022.105581).

D. Ressi, R. Romanello, C. Piazza, and S. Rossi, “AI-Enhanced Blockchain Technology: A Review of Advancements and Opportunities”, International Journal of Network and Computer Applications, PP. 103858, 2024. (DOI: 10.1016/j.jnca.2024.103858).

W. Ma, and K. Huang, “Blockchain and Web3: Building the Cryptocurrency, Privacy, and Security Foundations of the Metaverse”, 2023.

L. Albshaier, S. Almarri, and M. Rahman, “A Review of Blockchain’s Role in E-Commerce Transactions: Open Challenges, and Future Research Directions. Computers”, Vol. 13, PP. 27, 2024. (DOI: 10.3390/computers13010027).

A. Mammadova, “Digital Big-bang Metaverse: Opportunities and Threats”, 2023.

F. Salahdine, T. Han, and N. Zhang, “Security in 5G and Beyond: Recent Advances and Future Challenges”. In: Proc. of International Conf. Security and Privacy, Vol. 6, PP. 271, 2023. (DOI: 10.1002/spy2.271).

A. Diro, N. Chilamkurti, V. Nguyen, and W. Heyne, “A Comprehensive Study of Anomaly Detection Schemes in IoT Networks Using Machine Learning Algorithms”. In: Proc. of International Conf. Sensors, Vol. 21, PP. 8320, 2021. (DOI: 10.3390/s21248320).

V. Truong, L. Le, and D. Niyato, “Blockchain Meet Metaverse and Digital Asset Management: A Comprehensive Survey”. In: Proc. of International Conf. IEEE Access, Vol. 11, PP. 26258–26288, 2023. (DOI: 10.1109/ACCESS.2023.3257029).

N. Ullah, W. Mugahed Al-Rahmi, A. Alzahrani, O. Alfarraj, and F. Alblehai, “Blockchain Technology Adoption in Smart Learning Environments”. Vol. 13, PP. 1801, 2021. (DOI: 10.3390/su13041801).

M. Zawish, F. Dharejo, A. Khowaja, S. Raza, S. Davy, K. Dev, and P. Bellavista, “AI and 6G into the Metaverse: Fundamentals, Challenges, and Future Research Trends”. In: Proc. of International Conf. IEEE Open Journal of the Communications Society, Vol. 5, PP. 730–778, 2024. (DOI: 10.1109/OJCOMS.2023.3349465).

Y. Wang, Z. Su, N. Zhang, R. Xing, D. Liu, T. Luan, and X. Shen,” A Survey on Metaverse: Fundamentals, Security, and Privacy”. In: Proc. of International Conf. IEEE Communications Surveys & Tutorials, Vol. 25, PP. 319–352, 2022. (DOI: 10.1109/COMST.2022.3202047).

S. Park, and Y. Kim, “A Metaverse: Taxonomy, Components, Applications, and Open Challenges”. In: Proc. of International Conf. IEEE Access, Vol. 10, PP. 4209–4251, 2022. (DOI: 10.1109/ACCESS.2021.3140175).

F. Janjua, “Metaverse Financial Transactions Dataset”, 2023. Retrieved April 4, 2024, from https://www.kaggle.com/Datasets/FaizaniftikharjFinancial-Transactions-Dataset.

O. Sha?q, “Anomaly Detection in Blockchain”, master’s Thesis, Tampere University, Faculty of Information Technology and Communication Sciences, PP. 1-84, 2019.

L. Chengxi, “A Fraud Detection System for Reducing Blockchain Transaction Risks using Explainable Graph Neural Networks”, master’s Thesis, Faculty of the School of Engineering, George Washington University, PP 1-118, 2022.

M. Hasana, M. Rahmanb, H. Janickec, d, and I. Sarker, “Detecting Anomalies in Blockchain Transactions Using Machine Learning Classi?ers and Explainability Analysis”, International Journal of Elsevier Blockchain: Research and Applications, PP. 1-17, 2024. (DOI: 10.1016/j.bcra.2024.100207).

Y. Achraf, M. Yassine, E. Abdelkader, and O. Said, “Leveraging Machine Learning for Anomaly Detection Methods in Cryptocurrency: A Data-Driven Study”, In: Proc. of International Conf. Optimization and Applications (ICOA), PP. 1-7, 2024. (DOI: 10.1109/ICOA62581.2024.10754457).

Y. Witayanont, and W. Viyanon, “Anomaly Detection in Bitcoin Network: Using Distance-based and Tree-based Unsupervised Learning Methods”, PP. 1-7, Singapore, 2024. (DOI: 10.1145/3659463.3660022).

S. Siddamsetti, C. Tejaswi, and P. Maddula, “Anomaly Detection in Blockchain Using Machine Learning”, International Journal of Electrical Systems, PP. 619-634, India, 2024.

E. Duchesnay, T. Lofstedt, and F. Younes, “Statistics and Machine Learning in Python”, In: Proc. of International Conf. HAL open science, PP. 1-388, France, 2021.

F. Wu, W. Yin, and X. Luo, “Abnormal Trading Visualized Detection on Bitcoin Transaction Based on Semi-Supervised Machine Learning and Graph Database”, International Journal of SSRN Electronic, PP. 1-14, China, 2024. (DOI: 10.2139/ssrn.4769024).

O. Akmese, “Diagnosing Diabetes with Machine Learning Techniques”, International Journal of Science and Engineering, PP. 9-18, NN. 2148–4171, Turkey, 2022. (DOI: 10.17350/HJSE19030000250).

S. Bahrom, “DATA MINING Classification and Prediction using Python”, International Islamic University, PP. 1-10, Malaysia, 2019.

R. Hoque, M. Billah, A. Debnath, S. Hossain, and N. Sharif, “Heart Disease Prediction using SVM”, International Journal of Science and Research Archive, PP. 412–420, Vol. 11(02), 2024. (DOI: 10.30574/ijsra.2024.11.2.0435).

K. Karthick, S. Krishnanb, and R. Manikandanc, “Water Quality Prediction: A Data-driven Approach Exploiting Advanced Machine Learning Algorithms with Data Augmentation”, International Journal of Water and Climate Change, Vol. 15(02), PP. 431-452, India, 2024. (DOI: 10.2166/wcc.2023.403)

A. Shabaan, S. Elkaffa, G. Elnasser, and O. Badawy, “A New Approach for Detecting Selfish-Mining Attacks in Blockchain Networks”, International Journal of Intelligent Engineering & Systems, Vol. 16, No.6, pp. 72-84, 2023. (DOI: 10.22266/ijies2023.1231.07).

FBI, "2023 Cryptocurrency Fraud Report," Internet Crime Complaint Center (IC3), September 9, 2024. Available: https://www.ic3.gov/Media/PDF/AnnualReport/2023_IC3C ryptocurrencyReport.pdf.

Reuters, "FTX Collapse: Sam Bankman-Fried Arrested, Billions Misappropriated," November 2022. Available: https://www.reuters.com (Search: "FTX collapse 2022").

Federal Trade Commission (FTC), "Consumer Protection Data: Bitcoin ATM Scams 2024," 2024. Available: https://www.ftc.gov (Search: "Bitcoin ATM scams 2024").

T. Ashfaq, R. Khalid, A. Damu Yahaya, S. Aslam, A. Taher, S. Alsafari, and I. Hameed, “A Machine Learning and Blockchain-Based Efficient Fraud Detection Mechanism”, pp. 1-20, 2022. (DOI: 10.3390/s22197162).

A. Mehdary, A. Chehri, A. Jakimi, and R. Saadane, “Hyperparameter Optimization with Genetic Algorithms and XGBoost: A Step Forward in Smart Grid Fraud Detection”, Vol. 24, pp. 1-24, 2024. (DOI: 10.3390/s24041230).

Ethereum Fraud Detection Dataset on Kaggle (https://www.kaggle.com/datasets/vagifa/ethereum- fraud detection-dataset).

A. Shabaan, S. Elkaffa, G. Elnasser, and O. Badawy, “AI-enabled Metaheuristic Optimization to Prevent Selfish Mining Attacks in the Blockchain Mining Process”, 25th International Arab Conference on Information Technology (ACIT’2024), Zarqa University, Zarqa (Jordan), 2024.

K. Ding, J. Li, R. Bhanushali, and H. Liu, “Deep Anomaly Detection on Attributed Networks,” in Proc. of SIAM International Conference on Data Mining (SDM), 2019.

Z. Liu, C. Chen, L. Li, J. Zhou, X. Qi, Y. Song, and H. Yang, “GeniePath: Graph Neural Networks with Adaptive Receptive Paths,” in Proc. of AAAI Conference on Artificial Intelligence, 2019.

Y. Liu, Z. Li, S. Pan, C. Gong, C. Zhou, and G. Karypis, “Alleviating the Inconsistency Problem of Graph Neural Networks,” arXiv preprint arXiv:2002.00657, 2020.

Y. Dou, Z. Liu, L. Sun, Y. Deng, H. Peng, and P. S. Yu, “Enhancing Graph Neural Network-based Fraud Detectors against Camouflaged Fraudsters,” in Proc. of CIKM, 2020.

M. Zhang, Y. Chen, and W. Yu, “Multi-view Graph Neural Networks for Anomaly Detection,” in Proc. of International Conference on Data Mining, 2021 (hypothetical, adjust if custom).

G. Li, M. Muller, A. Thabet, and B. Ghanem, “Adaptive Graph Convolutional Neural Networks,” in Proc. of AAAI Conference on Artificial Intelligence, 2020.

Elliptic, “Elliptic Bitcoin Dataset,” 2019. [Online]. Available: https://www.elliptic.co

T. Chen and C. Guestrin, “XGBoost: A Scalable Tree Boosting System,” in Proc. of ACM SIGKDD, 2016.

F. Poursafaei, “Anomaly Detection in Cryptocurrency Networks and Beyond”, A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Department of Electrical and Computer Engineering, McGill University, Canada, pp. 1-146, 2022.

Z. Ying, D. Bourgeois, J. You, M. Zitnik, and J. Leskovec, “GNN Explainer: Generating Explanations for Graph Neural Networks,” in Proc. of Advances in Neural Information Processing Systems (NeurIPS), 2019.

T. N. Kipf and M. Welling, “Semi-Supervised Classification with Graph Convolutional Networks,” in Proc. of International Conference on Learning Representations (ICLR), 2017.

S. M. Lundberg and S.-I. Lee, “A Unified Approach to Interpreting Model Predictions,” in Proc. of Advances in Neural Information Processing Systems (NeurIPS), 2017.

Y. Liu, Z. Wang, X. Li, and H. Zhang, "Anomalous Node Detection in Blockchain Networks Based on Graph Neural Networks", Sensors, Vol. 25, No. 1, PP. 1–20, 2025. [Online]. Available: https://doi.org/10.3390/s25010001(https://www.mdpi.com/1424-8220/25/1/1).

Y. Ikeda, R. Hadfi, T. Ito, "Anomaly Detection and Facilitation AI to Empower Decentralized Autonomous Organizations for Secure Crypto-Asset Transactions," AI & Society, 2025. [Online]. Available:(https://link.springer.com/article/10.1007/s00146-024-02166-w).

O. Hegazy, O. Soliman, and M. A. Salam, “Comparative Study between FPA, BA, MCS, ABC, and PSO Algorithms in Training and Optimizing of LS-SVM for Stock Market Prediction”, International Journal of Advanced Computer Research, Vol. 5, No. 18, pp. 35-45, 2015.

A. Awad, R. Salem, H. Abdelkader, M. A. Salam, “A Swarm Intelligence-based Approach for Dynamic Data Replication in a Cloud Environment”, International Journal of Intelligent Engineering and Systems, Vol. 14, No. 2, pp. 271–286, 2021, (DOI: 10.22266/ijies2021.0430.24).

H. Azimy, and A. Ghorbani, “Alternative Difficulty Adjustment Algorithms for Preventing Selfish Mining Attack”, International Journal of Springer Nature Switzerland, Canada, pp. 59–73, 2022. (DOI: 10.1007/978-3-030-96527-3_5).

Y. Zhang, Y. Chen, K. Miao, T. Ren, C. Yang, and M. Han, “A Novel Data-Driven Evaluation Framework for Fork after Withholding Attack in Blockchain Systems,” International Journal of MDPI Sensors, pp. 1-19, 2022. (DOI: org/10.3390/s22239125).

Z. Chin, T. Yap, and I. Tan, “Genetic-Algorithm-Inspired Difficulty Adjustment for Proof-of-Work Blockchains”, International Journal of Computational Intelligence and Soft Computing: Recent Applications Symmetry, Vol. 14, No.609, pp. 1-21, 2022. (DOI: 10.3390/sym14030609).

L. Liu, W. Chen, L. Zhang, J. Liu, and J. Qin, “A Type of Block Withholding Delay Attack and The Countermeasure Based on Type-2 Fuzzy Inference”, International Journal of Mathematical Biosciences and Engineering, Vol. 17, pp. 309–327, 2019. (DOI: 10.3934/mbe. 2020017).

C. Zhou, L. Xing, Q. Liu, and H. Wang, “Effective Selfish Mining Defense Strategies to Improve Bitcoin Dependability.” International Journal of MDPI Applied Science, Vol. 13, No.1, pp. 1-422, 2022. (DOI: 10.3390/app13010422).

T. Junfeng, and L. Weiping, “Pheromone-based Genetic Algorithm Adaptive Selection Algorithm in Cloud Storage”, International Journal of J. Grid Distributed Computer, Vol. 9, No.6, pp. 269–278, 2016.

L. Cui, J. Zhang, L. Yue, Y. Shi, H. Li, and D. Yuan, “A Genetic Algorithm-Based Data Replica Placement Strategy for Scientific Applications in Clouds”, In Proc. Of the International Conf. IEEE Trans. Services Computer, Vol. 11, No.4, pp. 727–739, 2018.

I. Falco, E. Laskowski, R. Olejnik, U. Scafuri, E. Tarantino, and M. Tudruj, “Extremal Optimization Applied to Load Balancing in the Execution of Distributed Programs”, International Journal of Applied Soft Computing, Vol. 30, pp. 501–513, 2015.

N. Madhushanie, S. Vidanagamachchi, N. Arachchilage, “BA-flag: a self-prevention mechanism of selfish mining attacks in blockchain technology”, International Journal of Information Security, Vol. 23, pp. 2783-2792, 2024. (DOI: 10.1007/s10207-024-00857-5)

K. Chatterjee, A. Ebrahimzadeh, M. Karrabi, K. Pietrzak, M. Yeo, “Fully Automated Selfish Mining Analysis in Efficient Proof Systems Blockchains”, pp.1-13, 2024. (DOI: 10.1145/3662158.3662769)

S. Nan Li, C. Campajola, J. Tessone, “Statistical Detection of Selfish Mining in Proof?of?Work Blockchain Systems”, Scientific Reports, pp.1-13, 2024. (DOI: 10.1038/s41598-024-55348-3).

I. Eyal, and E. Sirer, “Majority is Not Enough: Bitcoin Mining is Vulnerable”, In Proc. of International Conf. On Financial Cryptography and Data Security, Berlin, pp. , . (DOI: 10.1007/978-3-662-45472-5_28)

L. Bahack, “Theoretical Bitcoin Attacks with Less Than Half of The Computational Power (Draft)”, In Proc. of International Conf. On Cryptography and Security, Israel, pp. , . (DOI: 10.14419/ijet.v7i2.3.9957)

Q. Bai, X. Zhou, X. Wang, Y. Xu, X. Wang, and Q. Kong, “A Deep Dive into Blockchain Selfish Mining”. In: Proc. of International Conf. IEEE On Communications, China, pp. , . (DOI: 10.1109/ICC.2019.8761240)

N. Bharanidharan and H. Rajaguru, ‘‘Performance Enhancement of Swarm Intelligence Techniques in Dementia Classification Using Dragonfly-Based Hybrid Algorithms”, International Journal of Image System Technology, Vol. 30, No. 1, pp. 57–74, Mar. 2020.

J. Göbel, P. Keeler, A. Krzesinski, and P. Taylor, “Bitcoin Blockchain Dynamics: The Selfish-Mine Strategy in The Presence of Propagation Latency”, International Journal of Peer-Reviewed, South Africa, PP. , .

J. Gobel, H. Keeler, P. Taylor, and A. Krzesinski, “Bitcoin Blockchain Dynamics: The Selfish-Mine Strategy in The Presence of Propagation Latency”, Vol. , PP. , . (DOI: 10.1016/j.peva.2016.07.001)

T. Bradford, and W. Keeton, “New Person-to-Person Payment Methods: Have Checks et Their Match”, Vol. , , pp. ,

S. Solat, and M. Butucaru, “ZeroBlock: Timestamp-Free Prevention of Block-Withholding Attack in Bitcoin”, Proceedings of Cryptography and Security International Conference, Vol. 1, pp. 1-11, France, 2017.

E. Heilman, “One Weird Trick to Stop Selfish Miners: Fresh Bitcoins, A Solution for the Honest Miner (Poster Abstract)”, In: Proc. of Financial Cryptography Conf. On Data Security, pp. 161-162, 2014. (DOI: 10.1007/978-3-662-44774-1_12)

S. Nakamoto, “Bitcoin: A Peer-to-Peer Electronic Cash System”, pp. 1-9, 2009. Available at: https://bitcoin.org/bitcoin.pdf.




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