EMBEDDED EXTENDED VISUAL CRYPTOGRAPHY SCHEMES
A visual cryptography scheme (VCS) is a kind of secret sharing scheme which allows the encoding of a secret image into shares distributed to participants. The beauty of such a scheme is that a set of qualified participants is able to recover the secret image without any cryptographic knowledge and computation devices. An extended visual cryptography scheme (EVCS) is a kind of VCS which consists of meaningful shares (compared to the random shares of traditional VCS). In this paper, we propose a construction of EVCS which is realized by embedding random shares into meaningful covering shares, and we call it the embedded EVCS. Experimental results compare some of the well-known EVCSs proposed in recent years systematically, and show that the proposed embedded EVCS has competitive visual quality compared with many of the well-known EVCSs in the literature. In addition, it has many specific advantages against these well-known EVCSs, respectively.
THE basic principle of the visual cryptography scheme (VCS) was first introduced by Naor and Shamir. VCS is a kind of secret sharing scheme that focuses on sharing secret images. The idea of the visual cryptography model proposed in is to split a secret image into two random shares (printed on transparencies) which separately reveals no information about the secret image other than the size of the secret image. The secret image can be reconstructed by stacking the two shares. The underlying operation of this scheme is logical operation OR.
In this paper, we call a VCS with random shares the traditional VCS or simply the VCS. In general, a traditional VCS takes a secret image as input, and outputs shares that satisfy two conditions: 1) any qualified subset of shares can recover the secret image; 2) any forbidden subset of shares cannot obtain any information of the secret image other than the size of the secret image. An example of traditional (2,2)-VCS can be found in Fig. 1, where, generally speaking, a –VCS means any out of shares could recover the secret image. In the scheme of Fig. 1, shares (a) and (b) are distributed to two participants secretly, and each participant cannot get any information about the secret image, but after
stacking shares (a) and (b), the secret image can be observed visually by the participants. VCS has many special applications, for example, transmitting military orders to soldiers who may have no cryptographic knowledge or computation devices in the battle field. Many other applications of VCS, other than its original objective (i.e., sharing secret image), have been found, for example, authentication and identification, watermarking and transmitting passwords etc.
The associated secret sharing problem and its physical properties such as contrast, pixel expansion, and color were extensively studied by researchers worldwide. For example, showed constructions of threshold VCS with perfect reconstruction of the black pixels.Furthermore, Eisen et al. proposed a construction of threshold VCS for specified whiteness levels of the recovered pixels. The term of extended visual cryptography scheme (EVCS) was first introduced by Naor et al. in, where a simple example of (2,2)-EVCS was presented. In this paper, when we refer to a corresponding VCS of an EVCS, we mean a traditional VCS that have the same access structure with the EVCS. Generally, an EVCS takes a secret image and original share images as inputs, and outputs shares that satisfy the following three conditions: 1) any qualified subset of shares can recover the secret image; 2) any forbidden subset of shares cannot obtain any information of the secret image other than the size of the secret image; 3) all the shares are meaningful images. Examples of EVCS can be found in the experimental results of this paper, such as Figs. 2–9. EVCS can also be treated as a technique of steganography. One scenario of the applications of EVCS is to avoid the custom inspections, because the shares of EVCS are meaningful images, hence there are fewer chances for the shares to be suspected and detected.
Visual cryptography is the art and science of encrypting the image in such a way that no-one apart from the sender and intended recipient even realizes the original image, a form of security through obscurity. By contrast, cryptography obscures the original image, but it does not conceal the fact that it is not the actual image.
LIMITATIONS OF EXISTING SYSTEM:
The existing system does not provide a friendly environment to encrypt or decrypt the data (images).
Proposed system Visual cryptography provides a friendly environment to deal with images. Generally cryptography tools supports only one kind of image formats. Our application supports .gif and .png (portable network graphics) formatted images and our application has been developed using swing and applet technologies, hence provides a friendly environment to users.
ADVANTAGES OF PROPOSED SYSTEM:
EVCS is flexible in the sense that there exist two trade-offs between the share pixel expansion and the visual quality of the shares and between the secret image pixel expansion and the visual quality of the shares. This flexibility allows the dealer to choose the proper parameters for different applications. Comparisons on the experimental results show that the visual quality of the share of the proposed embedded EVCS is competitive with that of many of the well-known EVCSs in the literature.
HARDWARE AND SOFTWARE REQUIREMENTS:
- System : Pentium IV 2.4 GHz.
- Hard Disk : 40 GB.
- Floppy Drive : 1.44 Mb.
- Monitor : 15 VGA Colour.
- Mouse : Logitech.
- Ram : 512 Mb.
- Operating system : Windows XP.
- Coding Language : JDK 1.6
- Tools : Netbeans