Characterization of the Atmosphere as a Random Bit-Stream Generator in a Weak Turbulence Regime

Anil K. Patnaik, Keith A. Wyman

Carlos O. Font, G. C. Gilbreath, Sergio R. Restaino +3 more

This paper investigates the extent to which atmospheric turbulence can be exploited as a random bit generator. Atmospheric turbulence is considered an inherently random process due to the complex inhomogeneous system composition and its sensitivity to changes in pressure, temperature, humidity, and wind conditions. A self-calibrating Mach-Zehnder interferometer was used to collect phase fluctuations in the temporal domain introduced to an optical beam propagating through the atmosphere. The recorded phase fluctuations were converted into bit streams that were further analyzed in order to search for evidence of randomness. Empirical data and results that characterize the degree of randomness produced in the temporal phase component of an optical wave propagating through the atmosphere are presented.

Carlos O. Font, David Bonanno, Hunter Long +2 more

Characterizing atmospheric turbulence through modeling dates back to the 1960's. For decades scientists have studied how to mitigate the effects of the atmospheric turbulence on communications and imaging systems, but learning how to use those properties of the atmosphere instead of mitigate them raise new challenges. Due to the fact that atmospheric turbulence is inherently a random process, it can be an ideal "key generator" for strongly secure information transfer. The purpose of this effort is to investigate to what extent the atmospheric turbulence can be exploited as a robust random number generator. In this paper we report the progress in characterizing the atmosphere and a random bitstream generator.

Kyle Thompson

Devashish Sanyal, Siddhartha Sen

Marvin D. Drake, Christophe F. Bas, David R. Gervais +6 more

We describe an experimental laboratory system that generates and distributes random binary sequence bit streams between two optical terminals (labeled Alice and Bob). The random binary sequence is generated through probing the optical channel of a turbulent atmosphere between the two terminals with coincident laser beams. The two laser beams experience differential phase delays while propagating through the atmospheric optical channel. The differential phase delays are detected and sampled at each terminal to yield raw random bit streams. The random bit streams are processed to remove bit errors and, through privacy amplification, to yield a bit stream known only to Alice and Bob. The same chaotic physical mechanism that provides randomness also provides confidentiality. The laboratory system yielded secret key bit rates of a few bits/second . For external optical channels over longer channel lengths with atmospheric turbulence levels, secret bit rates of 10 s of bits/second are predicted.