Group key agreement over free-space optical links

Hiroyuki Endo, Mikio Fujiwara, Mitsuo Kitamura, Orie Tsuzuki, Ryosuke Shimizu, Masahiro Takeoka, Masahide Sasaki

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Free-space optical (FSO) communications can offer secure connectivity thanks to the high directionality of the laser beam and the line-of-sight configuration. These security advantages are employed to realize high-speed key establishment between two distant parties, which is provably secure against an eavesdropper with unlimited computational resources. Besides, a well-maintained laser beam divergence allows group key agreement (GKA) among multiple parties. Here, we propose a novel method of GKA over FSO link—FSO-GKA. After numerically characterizing fundamental behaviors, we present a proof-of-concept demonstration of FSO-GKA using a 7.8-km terrestrial link. We achieve a group key rate of roughly 8 Mbps over a 58dB-loss channel based on 10-MHz on-off keying. We also investigate information leakage risks under several atmospheric conditions, which provides the basis for security certification of FSO-GKA. Our proposed scheme shows a new way to construct high-speed key exchange platforms.

Original languageEnglish
Pages (from-to)2525-2543
Number of pages19
JournalOSA Continuum
Issue number9
Publication statusPublished - 2020 Sept 15
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering


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