Visual cryptography scheme （VCS） is a secure method that encrypts a secret image by subdividing it into shadow images. Due to the nature of encryption VCS is categorized into two types： the deterministic VCS （DVCS...Visual cryptography scheme （VCS） is a secure method that encrypts a secret image by subdividing it into shadow images. Due to the nature of encryption VCS is categorized into two types： the deterministic VCS （DVCS） and the probabilistie VCS （PVCS）. For the DVCS, we use m （known as the pixel expansion） subpixels to represent a secret pixel. The PVCS uses only one subpixel to represent a secret pixel, while the quality of reconstructed image is degraded. A well-known construction of （k, n）-PVCS is obtained from the （k, n）-DVCS. In this paper, we show another construction of （k, n）-PVCS by extending the （k, k）-PVCS.展开更多
Visual secret sharing (VSS) is one of the cryptographic techniques of Image secret sharing scheme (ISSS) that performs encoding of secret message image (text or picture) into noise like black and white images, which a...Visual secret sharing (VSS) is one of the cryptographic techniques of Image secret sharing scheme (ISSS) that performs encoding of secret message image (text or picture) into noise like black and white images, which are called as shares. Shares are stacked together and secret message image is decoded using human visual system. One of the major drawbacks of this scheme is its poor contrast of the recovered image, which improves if computational device is available while decoding. In this paper, we propose to improve poor contrast of classical VSS schemes for text or alphanumeric secret messages and low entropy images. Initially, stacked image is binarized using dynamic threshold value. A mathematical morphological operation is applied on the stacked image to enhance contrast of the reconstructed image. Moreover, a method is proposed that allows the size of the structuring element to change according to the contrast and the size of a stacked image. We perform experiments for different types of VSS schemes, different share patterns, different share types (rectangle and circle), and low entropy images. Experimental results demonstrate the efficacy of the proposed scheme.展开更多
Visual secret sharing has received more and more attention over the past years due to the fact that neither complex computation nor cryptographic knowledge is required to decrypt the secret image directly according to...Visual secret sharing has received more and more attention over the past years due to the fact that neither complex computation nor cryptographic knowledge is required to decrypt the secret image directly according to the characteristics of the human vision system. Considering the issue of sharing the secret image at multiple image resolutions with the meaningful shadows, in this paper, we present a friendly progressive visual secret sharing scheme without expanding the image size in the shadows and the reconstructed secret image based on applying a 2x2-sized block-wise operation to generate the shadows block by block. The proposed method can achieve these benefits： 1） the generated shadows are meaningful, and their sizes are not expanded, and 2） the secret image can be recovered at different resolutions by stacking different quantities of shadows together. The experimental results also show that the proposed method is superior to other compared schemes.展开更多
A lossless image secret sharing using a simple Boolean operation is proposed. The concept of visual cryptography in the secret sharing scheme is used to redesign a lossless secret sharing scheme. To ensure that the re...A lossless image secret sharing using a simple Boolean operation is proposed. The concept of visual cryptography in the secret sharing scheme is used to redesign a lossless secret sharing scheme. To ensure that the reconstructed image is the true secret image, an authentication mechanism is imported into the proposed scheme to verify whether the shadows are authentic before reconstructing the secret image. The proposed scheme delivers much more effective performance than Chen and Wu＇s scheme.展开更多
Visual secret sharing(VSS) was used in the literature to encode and decode secret images until visual multi-secret sharing(VMSS) was proposed. Distinctly, multiple secret images can be encoded or decoded at a time in ...Visual secret sharing(VSS) was used in the literature to encode and decode secret images until visual multi-secret sharing(VMSS) was proposed. Distinctly, multiple secret images can be encoded or decoded at a time in VMSS; however, only one secret image can be done in VSS. In VMSS, secrets are encoded into noise-like shares which have finally been stacked altogether so as to disclose each of the secrets by specific operations, such as rotating, flipping and sliding. Though the noise-like shares can be decoded by those operations, it is just like a fly in the ointment since they are hard to manage, to recognize and even to stack orderly. Based on some researches about user-friendly VSS for generating meaningful shares, a new friendly VMSS scheme is presented in this paper for achieving two main goals. One is trying to encode multiple secrets at a time and the other is making the decoding process easy to manage. The experimental results prove that our proposed scheme does work.展开更多
基金supported in part by the Testbed@TWISC, National Science Council under the Grant No. 100-2219-E-006-001in part by National Natural Science Foundation of China under the Grant No. 60903210
文摘Visual cryptography scheme （VCS） is a secure method that encrypts a secret image by subdividing it into shadow images. Due to the nature of encryption VCS is categorized into two types： the deterministic VCS （DVCS） and the probabilistie VCS （PVCS）. For the DVCS, we use m （known as the pixel expansion） subpixels to represent a secret pixel. The PVCS uses only one subpixel to represent a secret pixel, while the quality of reconstructed image is degraded. A well-known construction of （k, n）-PVCS is obtained from the （k, n）-DVCS. In this paper, we show another construction of （k, n）-PVCS by extending the （k, k）-PVCS.
文摘Visual secret sharing (VSS) is one of the cryptographic techniques of Image secret sharing scheme (ISSS) that performs encoding of secret message image (text or picture) into noise like black and white images, which are called as shares. Shares are stacked together and secret message image is decoded using human visual system. One of the major drawbacks of this scheme is its poor contrast of the recovered image, which improves if computational device is available while decoding. In this paper, we propose to improve poor contrast of classical VSS schemes for text or alphanumeric secret messages and low entropy images. Initially, stacked image is binarized using dynamic threshold value. A mathematical morphological operation is applied on the stacked image to enhance contrast of the reconstructed image. Moreover, a method is proposed that allows the size of the structuring element to change according to the contrast and the size of a stacked image. We perform experiments for different types of VSS schemes, different share patterns, different share types (rectangle and circle), and low entropy images. Experimental results demonstrate the efficacy of the proposed scheme.
文摘Visual secret sharing has received more and more attention over the past years due to the fact that neither complex computation nor cryptographic knowledge is required to decrypt the secret image directly according to the characteristics of the human vision system. Considering the issue of sharing the secret image at multiple image resolutions with the meaningful shadows, in this paper, we present a friendly progressive visual secret sharing scheme without expanding the image size in the shadows and the reconstructed secret image based on applying a 2x2-sized block-wise operation to generate the shadows block by block. The proposed method can achieve these benefits： 1） the generated shadows are meaningful, and their sizes are not expanded, and 2） the secret image can be recovered at different resolutions by stacking different quantities of shadows together. The experimental results also show that the proposed method is superior to other compared schemes.
基金supported by the National Science Council under Grant No. NSC100-2218-E-468-002-MY2
文摘A lossless image secret sharing using a simple Boolean operation is proposed. The concept of visual cryptography in the secret sharing scheme is used to redesign a lossless secret sharing scheme. To ensure that the reconstructed image is the true secret image, an authentication mechanism is imported into the proposed scheme to verify whether the shadows are authentic before reconstructing the secret image. The proposed scheme delivers much more effective performance than Chen and Wu＇s scheme.
基金the National Science Council(Nos.NSC102-2221-E-415-014 and 102-2221-E-415-007)
文摘Visual secret sharing(VSS) was used in the literature to encode and decode secret images until visual multi-secret sharing(VMSS) was proposed. Distinctly, multiple secret images can be encoded or decoded at a time in VMSS; however, only one secret image can be done in VSS. In VMSS, secrets are encoded into noise-like shares which have finally been stacked altogether so as to disclose each of the secrets by specific operations, such as rotating, flipping and sliding. Though the noise-like shares can be decoded by those operations, it is just like a fly in the ointment since they are hard to manage, to recognize and even to stack orderly. Based on some researches about user-friendly VSS for generating meaningful shares, a new friendly VMSS scheme is presented in this paper for achieving two main goals. One is trying to encode multiple secrets at a time and the other is making the decoding process easy to manage. The experimental results prove that our proposed scheme does work.
