Wyniki wyszukiwania - BazTech

1

Random-Grid Based Region Incrementing Visual Secret Sharing

Kumar S., Sharma R. K.

Fundamenta Informaticae

|

2015

|

Vol. 137, nr 3

369--386

EN

The concept of region incrementing in visual cryptography was introduced to encrypt an image into multiple secrecy levels. But, it suffers from the pixel expansion increasing exponentially as the number of participants grows. In this paper, we propose a region incrementing visual secret sharing (RIVSS) scheme based on random grids. The proposed scheme is a general (k, n)-RIVSS scheme, in which any t (k ≤ t ≤ n) shares can be used to reconstruct the secret regions up to t − k + 1 levels. However, no information about the input image can be revealed by any k − 1 or fewer shares. With a nice property of region incrementing, the proposed scheme benefits by sharing an image without any pixel expansion and codebook requirement. We give formal proofs and experimental results to confirm both correctness and feasibility of our scheme.

2

Wybrane zagadnienia implementacyjne zaawansowanych algorytmów kryptografii wizualnej

Wiśniewski P., Ogiela M. R.

Pomiary Automatyka Kontrola

|

2014

|

R. 60, nr 12

1185--1188

PL

W publikacji scharakteryzowano dwa zaawansowane algorytmy kryptografii wizualnej: tzw. rozszerzoną kryptografię wizualną, w której istnieje możliwość umieszczenia fałszywych danych w sekretnych częściach obrazu, oraz skuteczną technikę szyfrowania obrazów kolorowych. Zaprezentowano także przykładową aplikację umożliwiającą użycie jednej z czterech metod oraz odczyt utajnionej informacji. Otrzymane wyniki działania opisywanych algorytmów potwierdzają wysoką skuteczność tego rodzaju technik kryptograficznych oraz zasadność ich praktycznego zastosowania.

EN

The paper presents two advanced visual cryptography algorithms: extended visual cryptography (EVCS) [2], where it is possible to place false information in shares of an image, and an effective encryption method for color images. This publication also presents an example application, which allows its user to execute one of four visual cryptography algorithms and to decrypt the secret information by joining shares. The first section shows the purpose of encrypting image data and main advantages of visual cryptography. In the second section an idea of secret sharing is presented. The third section describes visual cryptography techniques, where it is possible to create meaningful shares by encoding false information into shadow images. An example of (2,4)-threshold EVCS scheme is presented for a secret binary image. The fourth section presents a visual cryptography algorithm suitable for color images, which was analysed using a sample image. In the fifth section a visual cryptography system is proposed and its main features are presented, including procedure descriptions and obtained execution times of encryption algorithms. The summary presents the advantages of advanced visual cryptography algorithms and the utility of the application created for research. The obtained results of executing the described algorithms confirm the efficiency of these cryptographic techniques and the validity of its practical applications.

3

Preventing Cheating in Computational Visual Cryptography

Chang C-C., Chen T-H., Liu L-J.

Fundamenta Informaticae

|

2009

|

Vol. 92, nr 1-2

27-42

EN

Visual Cryptography (VC) has drawn much attention for providing the service of secret communication. Basically, VC is the process of encoding a secret into several meaningless shares and later decoding the secret by superimposing all or some of the shares without any computation involved. VC has been adopted to support some practical applications, such as image authentication, visual authentication, image hiding, and digital watermarking. Unfortunately, in many applications, VC has been shown to suffer from the "cheating problem" in which the disclosed secret image may be altered by malicious insiders who are called "cheaters." While ubiquitous computing has been well developed, it has recently occurred to people in both academia and industry that research could benefit more from computational VC by introducing light-weight computation costs in the decoding phase. In this paper, a simple scheme is proposed to conquer the cheating problem by facilitating the capability of share authentication. It is worthwhile to note that the proposed scheme can identify for certain whether cheating attacks have occurred or not, while other schemes that have the same objective frequently provide a vague answer. In addition, the proposed scheme effectively addresses the two main problems of VC, i.e., the inconvenience of meaningless share management and the challenge of achieving difficult alignment.

4

Friendly Color Visual Secret Sharing by Random Grids

Chen T-H., Tsao K-H., Yang Y-T.

Fundamenta Informaticae

|

2009

|

Vol. 96, nr 1/2

61-70

EN

The visual secret sharing (VSS) approach by random grids (RG-based VSS) has drawn people's attention "again" recently. Nevertheless, the current RG-based VSS approaches suffer from the problem of meaningless share images (cipher-grids) so that it is not user-friendly to manage noise-like share images. This paper presents a novel color RG-based VSS scheme aiming at providing the friendly color cipher-grids with all the advantages of traditional VSS schemes. To our best knowledge, this paper is the first effort to develop the friendly technique. The experimental results show that the scheme does work.