Topic
Visual cryptography
About: Visual cryptography is a research topic. Over the lifetime, 1724 publications have been published within this topic receiving 25300 citations.
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TL;DR: A new method for a visual cryptography scheme that uses phase masks and an interferometer to encrypt a binary image and confirm that a secret binary image that was sliced could be recovered by the proposed method.
Abstract: This paper presents a new method for a visual cryptography scheme that uses phase masks and an interferometer. To encrypt a binary image, we divided it into an arbitrary number of slides and encrypted them using an XOR process with a random key or keys. The phase mask for each encrypted image was fabricated nuder the proposed phase-assignment rule. For decryption, phase masks were placed on any path of the Mach-Zehnder interferometer. Through optical experiments, we confirmed that a secret binary image that was sliced could be recovered by the proposed method.
31 citations
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TL;DR: The proposed HVCS inherits the good features of traditional VCS, such as, loss-tolerant e.g., k, n threshold and simply reconstructed method, and can support signal processing in the encrypted domain SPED.
Abstract: In this paper, homomorphic visual cryptographic scheme HVCS is proposed. The proposed HVCS inherits the good features of traditional VCS, such as, loss-tolerant e.g., k, n threshold and simply reconstructed method, where simply reconstructed method means that the decryption of the secret image is based on human visual system HVS without any cryptographic computation. In addition, the proposed HVCS can support signal processing in the encrypted domain SPED, e.g., homomorphic operations and authentication, which can protect the user's privacy as well as improve the security in some applications, such as, cloud computing and so on. Both the theoretical analysis and simulation results demonstrate the effectiveness and security of the proposed HVCS.
31 citations
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26 Nov 2007TL;DR: This paper proposed in this paper a brand new type of visual cryptography (VC), namely, the VC in reversible style, for any two given secret images, two corresponding transparencies S1 and S2, also known as shares.
Abstract: We proposed in this paper a brand new type of visual cryptography (VC), namely, the VC in reversible style. For any two given secret images, two corresponding transparencies S1 and S2, also known as shares, can be produced. Both transparencies look noisy. However, if we stack the front views of both transparencies, then the first secret image is unveiled. On the other hand, if we stack the front view of S1 with the back view (the turn-over) of S2, then the second secret image is unveiled.
30 citations
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TL;DR: Two visual cryptographic methods are proposed to solve the problem of pixel expansion and to improve the visual effect of the stacked image at the same time and can satisfy the security and contrast conditions required by the VSS scheme.
Abstract: Most visual secret sharing (VSS) schemes need to encrypt a pixel of the secret image into m subpixels on the share; obviously, the shares are enlarged and so are the stacked images. A handful of studies try to solve the problem of pixel expansion, but little information is available on improving the visual effect of the stacked image. In addition, most of them do not mention how to deal with grey-level images. Since the secret is decoded by the human eye, the visual effect of the stacked image is an important issue in the study of the VSS scheme. This paper proposes two visual cryptographic methods to solve the problem of pixel expansion and to improve the visual effect of the stacked image at the same time. Unlike in previous studies, multiple pixels are simultaneously encoded each time. With the help of halftoning, the methods can be applied to encoding grey-level images. The experimental results show that these methods have a better visual effect on the stacked image compared with other researc...
30 citations
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TL;DR: It is shown that WS-VSS schemes can achieve clearer color reproduced images with a smaller pixel expansion compared to those using US-V SS schemes, while it is clarified that the basis matrices in both types of VSS schemes for black-white binary images are the same.
Abstract: We propose a weak security notion for visual secret sharing (VSS) schemes. Under such a weak security notion, VSS schemes are designed to be secure against attackers' eyesight, but are not unconditionally secure, in general. In this paper, we theoretically discuss the relation between unconditionally secure (US) and weakly secure (WS) VSS schemes and present two constructions of WS-VSS schemes for color images. We show that WS-VSS schemes can achieve clearer color reproduced images with a smaller pixel expansion compared to those using US-VSS schemes, while we clarify that the basis matrices in both types of VSS schemes for black-white binary images are the same. These results suggest that the proposed VSS schemes can be regarded as ramp (or nonperfect) VSS schemes for color secret images.
30 citations