[2] [2] BENDER W, GRUHL D, MORIMOTO N, et al. Techniques for data hiding [J]. IBM Systems Journal, 1996, 35(3/4): 313-336.

[5] [5] NI Z C, SHI Y Q, ANSARI N, et al. Reversible data hiding [J]. IEEE Transactions on Circuits and Systems for Video Technology, 2006, 16(3): 354-362.

[6] [6] CELIK M U, SHARMA G, TEKALP A M. Lossless watermarking for image authentication: a new framework and an implementation [J]. IEEE Transactions on Image Processing, 2006, 15(4): 1042-1049.

[7] [7] TIAN J. Reversible data embedding using a difference expansion [J]. IEEE Transactions on Circuits and Systems for Video Technology, 2003, 13(8): 890-896.

[9] [9] THODI D M, RODRGUEZ J J. Expansion embedding techniques for reversible watermarking [J]. IEEE Transactions on Image Processing, 2007, 16(3): 721-730.

[10] [10] CHANG C C, KIEU T D, CHOU Y C. Reversible data hiding scheme using two steganographic images [C]//Proceedings of the TENCON 2007-2007 IEEE Region 10 Conference. Taipei, China: IEEE, 2007: 1-4.

[11] [11] QIN C, CHANG C C, HSU T J. Reversible data hiding scheme based on exploiting modification direction with two steganographic images [J]. Multimedia Tools and Applications, 2015, 74(15): 5861-5872.

[12] [12] CHEN X F, HONG C Q. An efficient dual-image reversible data hiding scheme based on exploiting modification direction [J]. Journal of Information Security and Applications, 2021, 58: 102702.

[13] [13] LU T C, WU J H, HUANG C C. Dual-image-based reversible data hiding method using center folding strategy [J]. Signal Processing, 2015, 115: 195-213.

[15] [15] MEIKAP S, JANA B. Improved center-folding based directional pixel value ordering for reversible data hiding scheme [J]. Multimedia Tools and Applications, 2021, 80(4): 5617-5652.

[16] [16] LU T C, CHANG T C, SHEN J J. An effective maximum distortion controlling technology in the dual-image-based reversible data hiding scheme [J]. IEEE Access, 2020, 8: 90824-90837.

[17] [17] BHARDWAJ R, AGGARWAL A. Hiding clinical information in medical images: an encrypted dual-image reversible data hiding algorithm with base-3 numeral framework [J]. Optik, 2019, 181: 1099-1112.

[18] [18] PAILLIER P. Public-key cryptosystems based on composite degree residuosity classes [C]//Proceedings of the International Conference on the Theory and Applications of Cryptographic Techniques. Czech Republic: Springer, 1999: 223-238.