Optical security system using multi-phase separation and phase-wrapping method

다중 위상 분할과 위상 랩핑 방법을 이용한 광 암호화 시스템

  • Shin Chang Mok (Optical Signal Processing Lab, School of Electrical Engineering and Computer Science Kyungpook National University) ;
  • Kim Soo Joong (Optical Signal Processing Lab, School of Electrical Engineering and Computer Science Kyungpook National University) ;
  • Seo Dong Hoan (Division of Electrical and Electronics Engineering, Korea Maritime University)
  • 신창목 (경북대학교 전자전기컴퓨터공학부) ;
  • 김수중 (경북대학교 전자전기컴퓨터공학부) ;
  • 서동환 (한국해양대학교 전기전자공학부)
  • Published : 2005.06.01

Abstract

In this paper, we proposed an optical security system based on a gray-image exclusive-OR encryption using multi-phase separation and phase-wrapping method. For encryption, a gray image is sliced into binary images, which have the same pixel value, and these images are encrypted by modified XOR rules with binary random images. The XORed images and the binary images respectively combined and converted into full phase images, called an encrypted image and a key image. For decryption, when the encrypted image and key image are used as inputs on optical elements, Practically due to limited controllability of phase range in optical elements, the original gray image cannot be efficiently reconstructed by these optical elements. Therefore, by decreasing the phase ranges of the encrypted image and key image using a phase-wrapping method and separating these images into low-level phase images using multi-phase separation, the gray image can be reconstructed by optical elements which have limited control range. The decrytion process is simply implemented by interfering a multiplication result of encrypted image and key image with reference light. The validity of proposed scheme is verified and the effects, which are caused by phase limitation in decryption process, is analyzed by using computer simulations.

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