Chaotic semiconductor laser is a good candidate for secure communication and high-speed true random bit generator, for
its characteristics of broad bandwidth and prominent unpredictability. Based on the synchronization property and true
random bit generation characteristic of chaotic semiconductor lasers, physical secure key distribution is available. In this
work, we majorly show three key distribution schemes stemming from synchronized chaotic semiconductor lasers or
chaos-based key exchange protocol. The numerical results demonstrate that the security of the chaos-synchronization-based
key distribution scheme can be physically enhanced by adopting dynamic synchronization scheme or encrypted
key generation, and that of key distribution with chaos-based key exchange protocol is dependent on the security of the
exchange protocol and finally determined by the difficulty of regeneration the chaos system accurately.