Image Security using Visual Cryptography

Informations are being transferred through open channels and the security of those informations has been prime concerns. Apart from many conventional cryptographic schemes, visual cryptographic techniques have also been in use for data and information security. Visual cryptography is a secret sharing scheme as it breaks an original image into image shares such that, when the shares are stacked on one another, a hidden secret image is revealed. The Visual Cryptography Scheme is a secure method that encrypts a secret document or image by breaking it into image shares. A unique property of Visual Cryptography Scheme is that one can visually decode the secret image by superimposing shares without computation. Even to make the visual cryptography image shares more secure, public key encryption scheme is applied. Public key encryption technique makes image shares so secure that it becomes very hard for a third party to decode the secret image information without having required data that is a private key

Using graphic methods to challenge cryptographic performance

Block and stream ciphers have formed the traditional basis for the standardisation of commercial ciphers in the DES, AES, RC4, and so on. More recently alternative graphic methods such as Elliptic Curve Cryptography (ECC) have been adopted for performance gains. In this research we reviewed a range of graphic and non-graphic methods and then designed our own cipher system based on several graphic methods, including Visual Cryptography (VC). We then tested our cipher against RC4 and the AES algorithms for performance and security. The results showed that a graphics based construct may deliver comparable or improved security and performance in many of the required areas. These findings offer potential alternative avenues for post-quantum cryptographic research

Development of Visual Cryptography Technique for Authentication Using Facial Images

Security in the real world is an important issue to be taken care and to be encountered with various aspects and preventive measures. In the present era, whole major security concerns is the protection of this multimedia web is coming closer from text data to multimedia data, one of the data. Image, which covers the highest percentage of the multimedia data, its protection is very important. These might include Military Secrets, Commercial Secrets and Information of individuals. This can be achieved by visual Cryptography. It is one kind of image encryption. Incurrent technology, most of visual cryptography areembedded a secret using multiple shares. Visual is secret sharing technique used in visual cryptography which divides the secret image into multiple shares and by superimposing those shares the original secret image is going to be revealed, but it create a threat when an intruder get shares with which the image is going to be decrypted easily. However in these project work, an extremely useful bitwise operation is perform on every pixel with the help of key. The key is provided by new concept of sterilization algorithm. Initially Red, Green and Blue channels get separated from image and are going to be encrypted on multiple levels using multiple shares, convert an image into unreadable format and by combining all the shares in proper sequence the original secret image revealed

Naturally Rehearsing Passwords

We introduce quantitative usability and security models to guide the design of password management schemes --- systematic strategies to help users create and remember multiple passwords. In the same way that security proofs in cryptography are based on complexity-theoretic assumptions (e.g., hardness of factoring and discrete logarithm), we quantify usability by introducing usability assumptions. In particular, password management relies on assumptions about human memory, e.g., that a user who follows a particular rehearsal schedule will successfully maintain the corresponding memory. These assumptions are informed by research in cognitive science and validated through empirical studies. Given rehearsal requirements and a user's visitation schedule for each account, we use the total number of extra rehearsals that the user would have to do to remember all of his passwords as a measure of the usability of the password scheme. Our usability model leads us to a key observation: password reuse benefits users not only by reducing the number of passwords that the user has to memorize, but more importantly by increasing the natural rehearsal rate for each password. We also present a security model which accounts for the complexity of password management with multiple accounts and associated threats, including online, offline, and plaintext password leak attacks. Observing that current password management schemes are either insecure or unusable, we present Shared Cues--- a new scheme in which the underlying secret is strategically shared across accounts to ensure that most rehearsal requirements are satisfied naturally while simultaneously providing strong security. The construction uses the Chinese Remainder Theorem to achieve these competing goals

Visual cryptography with cheating shares

Visual cryptography is a technique that applies the human visual system to decode encrypted information, such as text, image and number, without any sophisticated devices and computing capabilities. Therefore, compared with the traditional cryptography, it is apparent that it saves a large amount of time and money on devices and computations. Also, visual cryptography provides the convenience for humans to carry out decryption with a portal card which is significant to the business application. In the past decade, visual cryptography has been thoroughly researched not only on its contrast and subpixel expansion, but also on its applications. The main contribution of this thesis is the security of visual cryptography related to the dishonest shareholders. This is the first known work concerning this variety of potentially secure problem. In the previous papers, the shareholders are inherently honest. However, in the real world, it is impossible to guarantee that every shareholder would be honest forever(e.g., because of the interest of business or military, some shareholders might change to be the traitors). Therefore, a new method based on visual authentication[16] is proposed and the improvement is also made. In this thesis, we also review the previous papers on different fields of the visual cryptography

Discrete Wavelet Transform based Cryptosystem

In this article, the authors proposed, implemented and analysed a symmetric key cryptographic algorithm that can be considered as a lossless encryption and decryption technique, advantageous especially in situations where, even a slight marginal distortion is not tolerable. In the proposed system, Haar wavelet is used initially, to transform the original target image into its frequency domain, followed by  encrypting the resulting sub-bands, so as to obtain a secure and reliable encrypted image. The resulting coefficients after Haar decomposition is scattered using a reversible weighing factor, suitably reversed and swapped to get the secure encrypted image. The encrypted image is  then correspondingly decrypted, by the reverse process to get back the original decrypted image. Statistical testing and security methods were used to evaluate and analyse the proposed cryptosystem and the results showed that the proposed system is cryptographically resistant to attacks and is also highly secure when compared to other cryptographic systems in the frequency domain

A Survey on Software Protection Techniques against Various Attacks

Software security and protection plays an important role in software engineering. Considerable attempts have been made to enhance the security of the computer systems because of various available software piracy and virus attacks. Preventing attacks of software will have a huge influence on economic development. Thus, it is very vital to develop approaches that protect software from threats. There are various threats such as piracy, reverse engineering, tampering etc., exploits critical and poorly protected software. Thus, thorough threat analysis and new software protection schemes, needed to protect software from analysis and tampering attacks becomes very necessary. Various techniques are available in the literature for software protection from various attacks. This paper analyses the various techniques available in the literature for software protection. The functionalities and the characteristic features are various software protection techniques have been analyzed in this paper. The main goal of this paper is to analyze the existing software protection techniques and develop an efficient approach which would overcome the drawbacks of the existing techniques