The interest in quantum-based security methods has been growing rapidly in recent years. New implementations of quantum key distribution and new network services supported by this solution are being introduced. The reason behind the growing popularity of quantum cryptography is its unrivaled security level: all eavesdroppers can be revealed through the application of the laws of physics. First of all, the rules of quantum mechanics ensure that any measurement modifies the state of the transmitted quantum bit. This modification can be discovered by the sender and the receiver. This makes passive eavesdropping impossible. Using protocols such as BB84, network users are able to send a string of bits coded by the polarized photons. After that, they can establish secure cryptographic keys through an unsecure channel using different key distillation methods. Major ongoing challenges include the control and management of security in systems using quantum cryptography, as well as tailoring security to specific end user's requirements and services.