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Title: Some Investigations on Phase Retrieval in Optical Asymmetric Cryptosystems
Authors: Fatima, A.
Keywords: Physics
Issue Date: 2018
Publisher: IIT Patna
Series/Report no.: TH-99;
Abstract: With rapid growth in communication channels, the world has shrunk with numerous transmission and exchange of data taking place each day. The data/information during transmission or during storage must be secured from unauthorized access or distribution. For this, different information security schemes have emerged over the years. In this context, optical cryptography which uses the properties of propagating light to encrypt the information has become relevant in the present scenario. Apart from encrypting the information, authentication and verification using optical methods has also emerged in the field of optical security. Optical features incorporated in any plaintext have been shown to provide unique signatures, which can be used to verify their authenticity. The first optical encryption technique to be reported was the double random phase encoding (DRPE) technique which employed the properties of Fourier transform to convert the input information to white stationary noise. The DRPE based schemes fall into the category of symmetric cryptosystems which were shown to be vulnerable to different attacks. To overcome the vulnerability, asymmetric cryptosystems were introduced which showed resistance to the known plaintext attack. However, the asymmetric optical cryptosystems were later shown to be breached by the specific attack. Hence, there has been a constant effort by researchers to develop asymmetric cryptosystems that have higher degree of robustness against these attacks. Over the years, different features of the optical field like the interference of light, polarization, holography and different optical transforms have been used to secure information. Polarization based encoding has become a preferred choice for optical cryptography because Stokes formalism used for the analysis can provide real ciphertexts which is an added benefit. In addition to the optical methods, different computational optics tools have also been used for developing cryptosystems and in their cryptanalysis. Phase retrieval algorithms are one such technique that finds application in different aspects of optical security.
Appears in Collections:05. PH

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