Human authentication is the process of verifying the identity of a person seeking access to a system, network, or resource. As digital services proliferate, establishing secure, usable, and privacy-preserving authentication has become one of the most critical challenges in information security. This survey provides a comprehensive overview of the principal categories of human authentication, covering knowledge-based methods (passwords and PINs), token-based methods (smart cards, OTPs, hardware tokens), physiological biometrics (fingerprint, iris, face, hand geometry, vein patterns), and behavioral biometrics (keystroke dynamics, gait, touch gestures, voice). We further discuss continuous and implicit authentication, multi-factor authentication (MFA), and the integration of steganography and cryptographic techniques for securing biometric templates during remote transmission. Emerging challenges such as presentation attacks (spoofing), liveness detection, deep-fake threats, and privacy concerns are examined. Finally, we highlight open research directions including AI-driven authentication, decentralised identity, and post-quantum authentication protocols
ANTONIOS MARINOS RAFTOPOULOS (Mon,) studied this question.