A New Visual Multi-Secrets Sharing Scheme by Random Grids

Abstract

In (2, 2)-visual secret sharing (VSS) schemes, a common type of (k, n)-threshold VSS schemes, secret information can be decoded directly through only two shares by using a human vision system. Several studies have analyzed methods of simplifying the decoding process and refining encoding to pass more secret images through two identical shares. However, limited secret images are retrieved, and the quality of the recovered images is low. This paper proposes an advanced (2, 2)-VSS scheme that can embed N secret images into two rectangular shares. Compared with other related VSS schemes, more secret images can be encrypted and the distortion is adjustable in the proposed scheme, yielding more flexibility in theory and practice.

Advanced fault-tolerant visual multi-secret sharing scheme

“…Some disadvantages of the mentioned scheme [12] are as follows: the distortions are fixed, the input secret image should be a square, and the number of input secret images should be < or = 4. To address these disadvantages, Chang et al [14,15] proposed some advanced schemes.…”

“…In the VMSSS [15] , the input images 𝑆 0 , 𝑆 1 , • • • , 𝑆 𝑁−1 of size 𝑚 × 𝑛 pixels are encoded into two shares 𝐺 1 and 𝐺 2 , and integer 𝑝 is selected according to user requirements (must be a positive factor of the width of the image 𝑚 ). Two consecutive images are randomly selected, and each set (2𝑝 pixels) is processed using Chang and Juan' s scheme [14] .…”

“…Encoding more than one image simultaneously is efficient with respect to time and space costs. Several studies have proposed and discussed schemes for encoding multiple images simultaneously [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] . The scheme proposed by Shyu [10] in 2009 is an extension of that proposed by Shyu [3] in 2007, which can encode two images simultaneously.…”

“…However, in those approaches, a restraint is imposed on the shape of the input images [11][12][13] ; that is, only square images can be input. To ensure more flexibility regarding the size, Chang et al [14,15] proposed RG-based VMSSSs that can encrypt rectangular images. In these schemes, the confidential content can be reconstructed when users stack two shares with a specific offset and roll them into a cylinder.…”

“…In 2016, Lin and Juan used the ideas described by Chang and Juan [14] in 2012, and Juan et al [22] in 2016 to propose an advanced scheme [25] that can encode two images into two shares, and the images can be reconstructed by stacking two imperfectly aligned shares. In the present paper, we combine the ideas presented by Chang et al [15] in 2018, and Juan and Chen [23] in 2018 and propose a faulttolerant multi-SSS that encodes more than two secret images into two shares simultaneously without pixel expansion.…”