The potentials for and limitations to the use of intensity fluctuations of laser beams propagating through a turbulent atmosphere for generating random data when keying in confidential optical communication systems are analyzed. The technique is based on the reciprocity theorem for optical fields. Light propagation in a system of two transceivers directed at each other, the signals from which are distorted by an atmospheric channel, is numerically simulated. An experimental setup is created; the generation of random correlated signals in such a system is experimentally studied. A need for low-pass filtering of signals received is experimentally ascertained. The efficiency of this filtration is estimated. The dependences of the correlation coefficient on the geometrical parameters of the system and turbulent conditions along the propagation path are derived from the numerical simulation in a wide range of distances, aperture radii, and values of turbulence intensity. Theoretical results are shown to be in a good agreement with the results of laboratory experiments.
laser radiation, confidential optical communication, cryptography, atmospheric turbulence, intensity fluctuations, reciprocity theorem
- Fürst H., Weier H., Nauerth S., Marangon D.G., Kurtsiefer C., Weinfurter H. High speed optical quantum random number generation // Opt. Express. 2010. V. 18, N 12. P. 13029–13037. DOI: 10.1364/OE.18. 013029.
- Fiorentino M., Santori C., Spillane S.M., Beausoleil R.G., Munro W.J. Secure selfcalibrating quantum random-bit generator // Phys. Rev. 2007. V. 75, N 3. DOI: 10.1103/PhysRevA.75.032334.
- Gabriel C., Wittmann C., Sych D., Dong R., Mauerer W., Andersen U.L., Marquardt C., Leuchs G. A generator for unique quantum random numbers based on vacuum states // Nat. Photon. 2010. V. 4, N 10, P. 711–715. DOI: 10.1038/NPHOTON.2010.197.
- Bennett C.H., Brassard G. Quantum cryptography: public key distribution and coin tossing // Theor. Comput. Sci. 2014. V. 560, N 1. P. 7–11. DOI: 10.1016/j.tcs. 2014.05.025.
- Sidorov V.V., Karpov A.V., Sulimov A.I. Meteornaya generatsiya sekretnyh klyuchej shifrovaniya dlya zashchity otkrytyh kanalov svyazi // Inform. tekhnol. i vychislitel'nye sistemy. 2008. N 3. P. 45–54.
- Sulimov A.I., Galiev A.A., Karpov A.V., Markelov V.V. Verification of wireless key generation using software defined radio // Proc. Intern. Siberian Conf. on Control and Commun. (SIBCON). Tomsk, Russia. 2019. P. 1–6. DOI: 10.1109/SIBCON.2019.8729607.
- Sulimov A.I., Karpov A.V. Performance evaluation of meteor key distribution // Proc. the 12th Intern. Conf. on Security and Cryptography (SECRYPT-2015). Colmar, France. 2015. P. 392–397.
- Premnath S.N., Jana S., Croft J., Gowda P.L., Clark M., Kasera S.K., Patwari N., Krishnamurthy S.V. Secret key extraction from wireless signal strength in real environments // IEEE Trans. Mobile Comput. 2013. V. 12, N 5. P. 917–930.
- Wallace J.W., Sharma R.K. Automatic secret keys from reciprocal MIMO wireless channels: Measurement and analysis // IEEE Trans. Inf. Forensics Security 2010. V. 5, N 3. P. 381–392.
- Minet J., Vorontsov M.A., Polnau E., Dolfi D. Enhanced correlation of received power-signal fluctuations in bidirectional optical links // J. Opt. 2013. V. 15, N 2. P. 022401.
- Drake M.D., Bas C.F., Gervais D.R., Renda P.F., Townsend D., Rushanan J.J., Francoeur J., Donnangelo N.C., Stenner M.D. Optical key distribution system using atmospheric turbulence as the randomness generating function: Classical optical protocol for information assurance // Opt. Eng. 2013. V. 52, N 5. P. 055008.
- Wang N., Song X., Cheng J., Leung V.C. Enhancing the security of free-space optical communications with secret sharing and key agreement // J. Opt. Commun. Netw. 2014. V. 6, N 12. P. 1072–1081.
- Shapiro J.H., Puryear A.L. Reciprocity-enhanced optical communication through atmospheric turbulence – Part I: Reciprocity proofs and far-field power transfer optimization // J. Opt. Commun. Netw. 2012. V. 4, N 12. P. 947–954.
- Bornman N., Forbes A., Kempf A. Random number generation & distribution out of thin (or thick) air // J. Opt. 2020. V. 22, N 7. P. 075705. DOI: 10.1088/ 2040-8986/ab9513.