Blockchain and Biometrics: Survey, GDPR Analysis, and Future Directions

Biometric recognition, as an efficient and hard-to-forge method of identification and verification, has become an indispensable part of the current digital world. Meanwhile, blockchain has been widely received by both research and industry. Researchers have started to speculate on the pros and cons when these two technologies cross paths. This paper provides a survey of the literature on the combination of blockchain and biometrics and includes a first legal analysis of this integration based on GDPR. Although the integration of blockchain technology into the biometric sector is still in its infancy, this paper aims to provide a holistic understanding of blockchain applicability in biometrics. This article examines several patterns, including biometric-bound public-key credentials, distributed identity management, and auditable biometric services. The survey distinguishes applications where blockchain provides a genuine technical advantage from those where it is not fundamentally required, and identifies its role as an integrity and audit layer around off-chain biometric storage and processing. Challenges and limitations when combining blockchain and biometrics are also discussed; e.g., blockchain networks may not be efficient or economical for some real-time biometric applications. Finally, we discuss key legal aspects of the EU General Data Protection Regulation (GDPR) related to this combination of technologies.