ECG-Based Biometric Authentication: A Comprehensive Survey of Methods, Challenges, and Future Directions

Biometric authentication offers a vital alternative to vulnerable password-based systems. The electrocardiogram (ECG) is a particularly promising modality due to its inherent liveness detection and spoof-resistance. Driven by the proliferation of wearable devices, ECG biometrics enables continuous and discreet user verification. While prior works have categorized methods, this survey provides a critical, deployment-focused analysis of the field. We structure our review around a systematic methodology, present a quantitative synthesis of performance benchmarks on standard datasets, and conduct an in-depth analysis of the primary obstacles to real-world adoption, including template aging, scalability, and security vulnerabilities. Finally, we outline key future research directions required to bridge the gap between laboratory results and robust, scalable applications.