Free-space optical (FSO) communications offer high-capacity wireless transmission due to their plentiful properties originated from higher carrier frequency. These properties also yield a greater security advantage: the high directionality of the laser beam and the line-of-sight configuration can reasonably restrict an attack model launched by an eavesdropper (Eve). Secret key agreement over FSO links (FSO-SKA) employs this security advantage for key establishment between two distant parties, which is secure against Eve even with unbounded computer resources. In this chapter, we numerically evaluate the performance of FSO-SKA for satellite laser communications under the given power constraint. We also compare the performance of FSOSKA and quantum key distribution (QKD). Our result shows that FSO-SKA can generate a key even for the distance between geostationary orbit satellite and ground station. We anticipate that FSO-SKA has a potential to extend the secure satellite networks to global scale, which is hard only with QKD.

Chapter Contents:

• 52.1 Introduction
• 52.2 Secret key agreement
• 52.3 Channel model
• 52.3.1 Generalized on-off keying
• 52.3.2 Secret key rate for GOOK
• 52.4 Numerical investigation of secret key rate
• 52.5 FSO-SKA versus QKD
• 52.6 Conclusion
• Acknowledgments
• References

Inspec keywords: satellite links; optical links; satellite ground stations; telecommunication security; numerical analysis; free-space optical communication; quantum cryptography

Other keywords: line-of-sight configuration; satellite laser communications; Eve; geostationary orbit satellite; eavesdropper; secure satellite networks; unbounded computer resources; laser beam; quantum key distribution; attack model; FSO-SKA links; satellite network security; ground station; free-space optical communications; QKD; secret key agreement

Subjects: Free-space optical links; Cryptography; Satellite communication systems; Other numerical methods