Experimental noise-free information recovery via reference beam encryption

MONTOYA, SANTIAGO; ROBERTO TORROBA; JOHN FREDY BARRERA; ALEJANDRO VELEZ; ALEXIS JARAMILLO; ALEJANDRO MIRA

San Diego

Congreso; SPIE Optical Engineering + Applications; 2018

SPIE

Optical encryption is an open and prolific field with a continual growth. Several cryptosystems as the 4f encrypting system, joint transform correlator (JTC), joint free space cryptosystem (JFSC) and the fractional JTC (FrJTC) cryptosystem have demonstrated a high-performance in data protection. The experimental implementation of each architecture shows different performances, opening a wide area of research. In this work we experimentally implement an interferometric cryptosystem in which the encryption key is a ground glass diffuser (GGD) located in the reference arm. In the object arm, the informationto be encoded is displayed in a spatial light modulator placed in contact with another GGD representing the input object plane. In the setup a lens brings the Fourier transform of the input object plane. In the cryptosystem, the encryption process is achieved by the interference between the Fresnel transform of the encryption key and the Fourier transform of the input object plane. This interference pattern is registered by a CMOS camera. The free propagation distance z between the encryption key plane and the output plane determines the correct Fresnel transform of the key in the register plane. Then, for the decryption process, both the encrypted data and the information of the Fresnel transform of the key at the correct distance are necessary. In order to test the capabilities of the cryptosystem, we implemented experimentally QR codes asan information container making possible a protocol for a noise-free information recovery. The experimental results show the viability and applicability of the proposal.