Key management and user authentication systems and methods for quantum cryptography networks that allow for users securely communicate over a traditional communication link (TC-link). The method includes securely linking a centralized quantum key certificate authority (QKCA) to each network user via respective secure quantum links or “Q-links” that encrypt and decrypt data based on quantum keys (“Q-keys”). When two users (Alice and Bob) wish to communicate, the QKCA sends a set of true random bits (R) to each user over the respective Q-links. They then use R as a key to encode and decode data they send to each other over the TC-link.