Visual cryptography

About: Visual cryptography is a research topic. Over the lifetime, 1724 publications have been published within this topic receiving 25300 citations.

Rushmore: securely displaying static and animated images using TrustZone

Abstract: We present Rushmore, a system that securely displays static or animated images using TrustZone. The core functionality of Rushmore is to securely decrypt and display encrypted images (sent by a trusted party) on a mobile device. Although previous approaches have shown that it is possible to securely display encrypted images using TrustZone, they exhibit a critical limitation that significantly hampers the applicability of using TrustZone for display security. The limitation is that, when the trusted domain of TrustZone (the secure world) takes control of the display, the untrusted domain (the normal world) cannot display anything simultaneously. This limitation comes from the fact that previous approaches give the secure world exclusive access to the display hardware to preserve security. With Rushmore, we overcome this limitation by leveraging a well-known, yet overlooked hardware feature called an IPU (Image Processing Unit) that provides multiple display channels. By partitioning these channels across the normal world and the secure world, we enable the two worlds to simultaneously display pixels on the screen without sacrificing security. Furthermore, we show that with the right type of cryptographic method, we can decrypt and display encrypted animated images at 30 FPS or higher for medium-to-small images and at around 30 FPS for large images. One notable cryptographic method we adapt for Rushmore is visual cryptography, and we demonstrate that it is a light-weight alternative to other cryptographic methods for certain use cases. Our evaluation shows that in addition to providing usable frame rates, Rushmore incurs less than 5% overhead to the applications running in the normal world.

Notice of Violation of IEEE Publication Principles Binary watermarking technique based on Visual Cryptography

Abstract: With the explosive growth of internet technology robust methods are being developed to protect the proprietary rights of the multimedia. This paper considers the problem of embedding a binary watermark in a gray-level image using the concept of Visual Cryptography (VC). This paper proposes a watermarking scheme which offers better security than Hwang's method, so that, attackers will not be able to detect ownership information. The proposed scheme embeds the secret image without modifying the host image. In addition, the hidden secret image can be extracted without using the original host image and allows multiple watermarks to be embedded in the same image. The experimental results show that the proposed scheme is robust to withstand several image processing attacks such as JPEG compression, noise adding, sharpening and blurring.

Method for visual cryptography and counterfeit prevention of patterns

Abstract: The invention discloses a visual cryptography and counterfeit prevention method for hiding and maintaining encrypted image information. The visual cryptography and counterfeit prevention method for patterns comprises the following steps: inputting a confidential image S and migration parameters s and t; randomly generating a grey image R; and subjecting the confidential image S and the random image R to the Exclusive-OR operation to generate an encrypted image E, wherein the encrypted image E contains information of the confidential image S. The confidential image S hidden in the encrypted images E is restored by superposing two encrypted images E, thereby achieving the effect of counterfeit prevention. The visual cryptography and counterfeit prevention method for patterns is incorporatedwith rectangular or arc-shaped anti-counterfeiting icons to form counterfeit-prevention elements which are applied to the data carriers such as counterfeit-prevention files and negotiable securities.The counterfeit-prevention algorithm has the characteristics of easy identification, high difficulty in counterfeiting and the like.

Contrast optimal colored visual cryptography schemes

Abstract: Visual cryptography schemes allow the encoding of a secret image into n shares which are distributed to the participants, such that only qualified subsets of participants can "visually" recover the secret image. In colored threshold visual cryptography schemes, the secret image is composed of pixels taken from a given set of c colors. We study c-color (k, n)-threshold visual cryptography schemes and provide a characterization of contrast optimal schemes. More specifically, we prove that there exists a contrast optimal scheme that is a member of a special set of schemes, which we call canonical schemes, and that satisfy strong symmetry properties. Then we use canonical schemes to provide a constructive proof of optimality, with respect to the pixel expansion, of c-color (n, n)-threshold visual cryptography schemes.

Threshold Secret Sharing Scheme for Compartmented Access Structures

Abstract: In the realm of visual cryptography, secret sharing is the predominant method of transmission and reception of secure data. Most of the n, n secret sharing schemes suffer from one common flaw-locking of information when the all-n number of receivers are not available for some reason. This paper proposes a new method of compartmented secret sharing scheme where some threshold number of equally privileged from each compartment can retrieve data. This scheme rules out regeneration of secret image at the single compartment thereby eliminating the danger of misusing secret image. The key features of this scheme are: better visual quality of the recovered image with no pixel expansion; non-requirement of half toning of color images; less computational complexity by reconstructing secret through XORing and simple addition of all share images. This scheme is highly beneficial in applications where data has to be stored securely in a database and in cloud computing to synchronize information passed to different groups or clusters from a single host.