CIOP   05384
CENTRO DE INVESTIGACIONES OPTICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Time-varying signal encryption techniques based on dual random phase encoding setups applied to fiber optics links
Autor/es:
CUADRADO LABORDE, CHRISTIAN; DUCHOWICZ, RICARDO; TORROBA, ROBERTO; SICRE, ENRIQUE
Lugar:
Brasil
Reunión:
Congreso; 6th Iberoamerican Meeting on Optics, Lasers, and their Applications (RIAO-OPTILAS) 2007; 2007
Institución organizadora:
Unicamp, OSA, SPIE.
Resumen:
For security reasons, it is important to encode information in such a way that is dificult to decode it if one does not have a key, but easy to recover if one knows that key. Optical techniques have shown great potential in the field of information security to encode high-security images. At the middle 90s, Refregier and Javidi proposed a double random-phase encryption technique that encodes a primary image into stationary white noise [1]. The two random-phase masks placed in the input and the Fourier plane of a 4f system serve as the keys to the system. That was the starting point of a number of works in the field, between them,  Unnikrishnan et al. proposed an optical encryption system through double-random phase encoding by using the analogy between Fresnel di®raction patterns and the fractional Fourier transform [2,3]. In this case, an additional key is obtained, namely, the fractional order p of the fractional Fourier transform employed. On the other hand, for encoding time-varying signals transmitted through fiber optics links, sometimes non-quantum encryption set-ups are preferred over quantum-cryptographic schemes. This is so because the first are more tolerant to optical power losses, allow the use of o®-the-shelf components, and generally they can include optical amplifiers steps. This work propose two di®erent methods (closely related) to encode time-varying signals in the context of  fiber optics links. They can be considered as the temporal analogues of the Refs. 1, and 2-3. A comprehensive approach to the problem of producing time-limited encoded signals has been made together with the multiplexing possibilities of each system. Numerical simulations have been carried out to analyze the system performances. The obtained results indicate that these multiplexing encryption methods could be a good alternative to other well-established methods. REFERENCES: 1. P. Refregier and B. Javidi,  Optical image encryption based on input plane and Fourier plane random encoding, Opt. Lett. 20(7), 767-769 (1995). 2. G. Unnikrishnan, J. Joseph, and K. Singh, Optical encryption by double-random phase encoding in the fractional Fourier domain, Opt. Lett. 25(12), 887-889 (2000). 3.G. Unnikrishnan and K. Singh, Double random fractional Fourier-domain encoding for optical security, Opt. Eng. 39(11), 2853-2859 (2000).