Visual cryptography is an excellent cryptographic method by which the visual information is encrypted and decrypted with or without using of computer systems depending on the human visual system. In visual cryptography techniques, the carrier (with secret information) is divided into multiple shares, in particular any one of which does not reveal any knowledge about the secret information. In this chapter, a newly color component-based visual cryptographic technique, i.e., image share formation for image and video, has been introduced. As video is a sequential amalgamation of image frames, the same has also been implemented for video. In this time, the method supports the {k, n} threshold framework. Out of n transparencies, using k number of shares, the reformation is possible. Using the image, shares data may be embedded to different shares using steganography or watermarking techniques. Furthermore, some suitable comparisons also have been performed to measure the newly developed technique.
Top1. Introduction
Hiding information is a strategy for preventing unwanted access to material or for making information unavailable over a communication channel. Steganography is a method that extracts information via the use of appropriate cover carriers or media such as images, texts, audio recordings, and videos. Digital watermarking may be thought of as a kind of embedding that is either obvious or covert inside the cover signal. In most cases, the ownership of the copyright may be determined based on the apparent basis. The process of transforming plaintext into cypher text is referred to as cryptography. Another kind of cryptographic technique is known as visual cryptography. This form of cryptography allows the encryption process to be dependent on the human visual system. The translated visual information is then used to execute the decryption process in a manner that does not need the usage of a mathematical computer system. Visual cryptography has the potential to become one of the most superior levels of security module in the field of information security. This would allow for encrypted communication via digital cover medium. (P. S. Revenkar et al., 2010, Ankita Maheshwari, 2015).
Another kind of emerging cryptographic technology is known as visual cryptography. In visual encryption, a secret message is encoded as a collection of “shares” that can be graphically merged to disclose the original secret message. Different people receive the shares, and they can use them to decrypt the communication without having to figure out a complicated encryption method or find a hidden key. Originally suggested in 1994 by Moni Naor and Adi Shamir, the method has since found use in digital watermarking, private picture transfer, and identification systems among other places. You can classify visual encryption as either “basic” or “extended,” the former being the more common of the two. To divide a hidden communication into two or more parts, visual cryptography's rudimentary technique of using one-time tokens is used. These tokens are then printed on transparency sheets, and the hidden message is revealed upon superimposing the sheets.
In contrast, extended visual encryption permits the generation of more than two shares, and these shares may be organized in such a way that the secret message is obscured without the knowledge of the proper combination of shares. Without the need for complicated encryption methods or passwords, visual cryptography is a helpful technique for securely and efficiently exchanging secrets. However, there are restrictions, such as the need for actual distribution of the shares, which may be problematic in some cases. Decryption of encrypted pictures is often accomplished by the use of Human Visual Intelligence (HVI) elements. Understanding cryptography or performing difficult mathematical computations is never required in order to share the carrier (Kimmo Halunen et al. 2021, Feng Liu et al. 2011). During the process of encryption, it will never attempt to conceal any information to itself. On occasion, though, it will make use of the method of breaking a covert picture down into a series of binary or patchy images or shares, which will make the covert image look to us as random noise. During the process of decryption, parts of the hidden picture files are pieced together, and thereafter they may at last be seen by the human visual system (In Koo Kang et al. 2011, Annalisa De Bonis et al. 2004).