International Journal on Recent and Innovation Trends in Computing and Communication ISSN: 2321-8169 Volume: 2 Issue: 8 2411 – 2414 _______________________________________________________________________________________________ 2411 IJRITCC | August 2014, Available @ http://www.ijritcc.org _______________________________________________________________________________________ A Hash Based Visual Cryptography Scheme for Image Authentication Gonela Shiva M.TECH(CNIS),Dept. of IT Sreenidhi Institute of Science & Technology Hyderabad, Telangana, India shivagonela342@gmail.com CH. Samson Associate professor & Associate Head Dept, of IT Sreenidhi Institute of Science & Technology Hyderabad, Telangana, India samchepuri@gmail.com Abstract — In this paper we have proposed a Hash based visual cryptography scheme for image authentication. The secret image to be transmitted is encoded into two shadow images called user share and key share. The Hash cryptographic algorithm is applied on each share, and the resultant Hash codes are concatenated with the shares, and sent to communication participants. The same Hash is used to verify the sender at the receiving end. Then the shares are stacked together to recover the original secret image. From the results obtained in our analysis, we conclude that the proposed scheme provides not only confidentiality but also image authentication. Keywords- Visual Cryptography; user share; key share; hash; image Authentication. __________________________________________________*****_________________________________________________ I. INTRODUCTION Visual Cryptography is a cryptographic technique which allows visual information such as text, pictures and images to be encrypted. An image is divided into n shares so that stacking of n shares will reveal the original image with loss of quality. Visual Cryptography is introduced by Moni Naor and Adi Shamir in 1994 [1]. They demonstrated a visual secret sharing scheme, where an image was broken up into n shares so that only someone with all n shares could decrypt the image, no n-1 shares would reveal the original image. Each pixel of the image divided into smaller blocks. There are always the same number while (transparent) and black blocks. If a pixel is divided into two parts, there is one white and black block. If the pixel is divided into four equal parts, there are two white and two black blocks. Text based passwords attacks have become common now a days there are different text based password attacks. So new schemes of authentication are been in research. One such Method is Visual cryptography which is used to generate different unidentified shares so that these shares can be shared between two or more parties so that stacking of these shares will help in identifying the original image message. Using the Hash of images will help in generating the hash of a secret image so that it is impossible to get the secret image back from hash code. This paper presents a method of using Visual Cryptography and Hashing to Store and authenticate the user. II. RELATED WORK Many authors published different Visual Cryptography Schemes for different applications. Each scheme has its own advantages and disadvantages. Noar and Shamir [2] have worked on Basic Visual Cryptography scheme. Ateniese et al. [3] have worked on Elegant Visual Cryptography scheme for general access structure based on the cumulative array method. Naor and Pinkas [4] have worked on methods of authentication and identification between two participants. Yang et al. [5] have worked on Cheating method against some Visual Cryptography scheme were discussed. The existing methods propose different authentication mechanism using visual cryptography where the generate images shares are stored in the database so that when the user insert the this secret share the system will retrieve the server share and stack both the shares, finally this stacked image is compared to the original image in database than user will be authenticated. This method degrades the performance of the system and increase the memory size of database as images take more memory. This method also suffers from the regular attacks if the attacker compromises the database server all the user credential will be stolen, the server shares can be used to guess the user share according to Yang et al. [5]. The rest of the paper is organised as follows. In Section II, the related work is mentioned. Section III describes the proposed approach. Section IV deals with the implementation results obtained in our analysis. Finally in Section V, we draw conclusions from the results obtained from our approach and mention future scope for the possible enhancement. III. PROPOSED APPROACH In order to overcome the above mentioned drawbacks we proposing a Hash based methodology using visual cryptography. The proposed approach consists of four phases as follows. A. Registration Phase In this phase, the user is asked to provide the information about the username, email-id and image that is wants to use for authentication. The system uses the visual cryptography technique to generate the image shares. It generates two secured shares using a system generated key string. B. Generating Image Shares The system uses the visual cryptography technique to generate the image shares. It generates two secured shares using a system generated key. C. Generating Hash Values of Shares