中国物理B ›› 2023, Vol. 32 ›› Issue (7): 74202-074202.doi: 10.1088/1674-1056/acbf27

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Optical encryption scheme based on spread spectrum ghost imaging

Jin-Fen Liu(刘进芬)1,2, Yue Dong(董玥)1, Le Wang(王乐)1, and Sheng-Mei Zhao(赵生妹)1,†   

  1. 1 Institute of Signal Processing and Transmission, Nanjing University of Posts and Telecommunications, Nanjing 210003, China;
    2 NanJing Tech University Pujiang Institute, Nanjing 211222, China
  • 收稿日期:2022-11-15 修回日期:2023-02-21 接受日期:2023-02-27 出版日期:2023-06-15 发布日期:2023-06-29
  • 通讯作者: Sheng-Mei Zhao E-mail:zhaosm@njupt.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 61871234 and 62001249), the Postgraduate Research & Practice Innovation Program of Jiangsu Province (Grant No. KYCX20 0729), the Natural Science Research Project of Higher Education of Jiangsu Province (Grant No. 20KJB510030), the Qing Lan Project of Jiangsu Province (Su Teacher's Letter[2022] No. 29), the Research project of NanJing Tech University Pujiang Institute (Grant No. njpj2022-1-25), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

Optical encryption scheme based on spread spectrum ghost imaging

Jin-Fen Liu(刘进芬)1,2, Yue Dong(董玥)1, Le Wang(王乐)1, and Sheng-Mei Zhao(赵生妹)1,†   

  1. 1 Institute of Signal Processing and Transmission, Nanjing University of Posts and Telecommunications, Nanjing 210003, China;
    2 NanJing Tech University Pujiang Institute, Nanjing 211222, China
  • Received:2022-11-15 Revised:2023-02-21 Accepted:2023-02-27 Online:2023-06-15 Published:2023-06-29
  • Contact: Sheng-Mei Zhao E-mail:zhaosm@njupt.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 61871234 and 62001249), the Postgraduate Research & Practice Innovation Program of Jiangsu Province (Grant No. KYCX20 0729), the Natural Science Research Project of Higher Education of Jiangsu Province (Grant No. 20KJB510030), the Qing Lan Project of Jiangsu Province (Su Teacher's Letter[2022] No. 29), the Research project of NanJing Tech University Pujiang Institute (Grant No. njpj2022-1-25), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

摘要: An optical encryption (OE) scheme based on the spread spectrum ghost imaging (SSGI), named as SSGI-OE, is proposed to obtain a high security with a smaller key. In the scheme, the randomly selected row number of a Hadamard matrix of order N is used as the secure key, and shared with the authorized user, Bob, through a private channel. Each corresponding row vector of the order-N Hadamard matrix is then used as the direct sequence code to modulate a speckle pattern for the ghost imaging system, and an image is encrypted with the help of the SSGI. The measurement results from the bucket detector, named as ciphertext, are then transmitted to Bob through a public channel. The illuminating speckle patterns are also shared with Bob by the public channel. With the correct secure key, Bob could reconstruct the image with the aid of the SSGI system, whereas the unauthorized user, Eve, could not obtain any useful information of the encrypted image. The numerical simulations and experimental results show that the proposed scheme is feasible with a higher security and a smaller key. For the 32×32 pixels image, the number of bits sent from Alice to Bob by using SSGI-OE (M=1024, N=2048) scheme is only 0.0107 times over a computational ghost imaging optical encryption scheme. When the eavesdropping ratio (ER) is less than 40%, the eavesdropper cannot acquire any information of the encrypted image. The extreme circumstance for the proposed SSGI-OE scheme is also discussed, where the eavesdropper begins to extract the information when ER is up to 15%.

关键词: optical encryption, ghost imaging, spread spectrum, correlated imaging

Abstract: An optical encryption (OE) scheme based on the spread spectrum ghost imaging (SSGI), named as SSGI-OE, is proposed to obtain a high security with a smaller key. In the scheme, the randomly selected row number of a Hadamard matrix of order N is used as the secure key, and shared with the authorized user, Bob, through a private channel. Each corresponding row vector of the order-N Hadamard matrix is then used as the direct sequence code to modulate a speckle pattern for the ghost imaging system, and an image is encrypted with the help of the SSGI. The measurement results from the bucket detector, named as ciphertext, are then transmitted to Bob through a public channel. The illuminating speckle patterns are also shared with Bob by the public channel. With the correct secure key, Bob could reconstruct the image with the aid of the SSGI system, whereas the unauthorized user, Eve, could not obtain any useful information of the encrypted image. The numerical simulations and experimental results show that the proposed scheme is feasible with a higher security and a smaller key. For the 32×32 pixels image, the number of bits sent from Alice to Bob by using SSGI-OE (M=1024, N=2048) scheme is only 0.0107 times over a computational ghost imaging optical encryption scheme. When the eavesdropping ratio (ER) is less than 40%, the eavesdropper cannot acquire any information of the encrypted image. The extreme circumstance for the proposed SSGI-OE scheme is also discussed, where the eavesdropper begins to extract the information when ER is up to 15%.

Key words: optical encryption, ghost imaging, spread spectrum, correlated imaging

中图分类号:  (Imaging and optical processing)

  • 42.30.-d
42.30.Wb (Image reconstruction; tomography) 42.30.Va (Image forming and processing)