# Integrating Visual Cryptography for Efficient and Secure Image Sharing on Social Networks
## 2 Background and Related Works  
### Background  
Traditional security mechanisms are resource-intensive, making reliable transmission challenging. Given the vulnerability of images to security attacks due to resource constraints, image encryption is crucial for visual privacy and security. Existing encryption techniques aim to secure communication between sensors. Asymmetric encryption methods are often impractical due to sensor resource limitations. Recent developments in Elliptic Curve Cryptography (ECC) have lowered computational costs but still require Public Key Infrastructure (PKI) support. Symmetric encryption algorithms necessitate an initial shared key between adjacent sensor pairs, presenting significant challenges for secure and efficient key distribution. While disseminating each sensor's key to neighboring nodes is a straightforward method, it can become complex and inefficient in social networks. The unique appearance of encrypted images may intrigue unauthorized users during transmission, heightening the risk of exposure. Given that sensors use wireless communication, any entity within the transmission can potentially intercept data, compromising the privacy of exchanged information [10]. VC is a method that utilizes the characteristics of HVS to decrypt encrypted images. Compared to other cryptographic schemes that rely on complex calculations, VC offers greater security and convenience. The core idea is to divide a secret image into multiple random shares, each of which contains no information about the original image. Secret sharing is one of the basic primitives of cryptography, which decentralizes the management of core secrets and keys, reducing the risk of theft and tolerating attacks. VC has applications in key negotiation, secure multi-party computation, digital signatures, transfer systems, and voting systems. During decryption, the encrypted shares are printed on transparent film and overlapped. The secret information from the original image can then be recovered through the HVS. Visually meaningful image encryption is a key topic in information security, aiming to balance image privacy and usability. Unlike traditional schemes that prioritize privacy while neglecting usability, VC ensures the security of image content and visual appearance. The ciphertext protects privacy while remaining visually appealing. This approach meets practical needs and provides new insights into information security. The VC encrypts a black-and-white secret image into \(n\) shares for distribution. The threshold property of SS ensures that the secret image can only be recovered when two or more participants stack their respective shares together. If a pixel to be encrypted is black (represented by 1), the corresponding pixels in the cover image are 1 and 0 (withwhite representing 0). The encrypted matrix can be obtained by permuting any column of the base matrix. VC offers a lightweight and secure image forwarding scheme by merging image processing and cryptography. Its threshold property ensures that encrypted images reveal no information about the original. As shown in Figure 1, each pixel in the secret image is divided into shares using a mathematical process based on basis matrices and column permutations. The black pixels in the shares are irreversible, leading to a loss of contrast and brightness in the decrypted image. The matrices \(S^{i},i\in\{0,1\}\) are basis matrices; we can obtain encryption collections \(C_{i}\) by permuting the columns of \(S^{i}\) in all possible ways. The basis matrices and the collections of the encoding matrices in the conventional \(2\times 2\)-VCS can be written in Equations (1)-(3):  
\[S^{0} =\left[ \begin{array}{cc}0&1\\ 0&1\end{array} \right],\quad S^{1}=\left[ \begin{array}{cc}0&1\\ 1&0\end{array} \right] \tag{1}\] \[C_{0} =\left\{\left[ \begin{array}{cc}0&1\\ 0&1\end{array} \right],\left[ \begin{array}{cc}1&0\\ 1&0\end{array} \right]\right\}\] (2) \[C_{1} =\left\{\left[ \begin{array}{cc}0&1\\ 1&0\end{array} \right]^{\prime}\left[ \begin{array}{cc}1&0\\ 0&1\end{array}