An Implementation of Picpass Algorithm for the Solution of Key Exchange Problem

Abstract

In this dissertation a PicPass algorithm is proposed for the solution of Key Exchange problem using Symmetric and Asymmetric key cryptography. Diffie and Hellman proposed an algorithm for key exchange. But this algorithm suffers from Man-in middle attack. So to overcome this problem Seo proposed another algorithm that uses text password for the agreement between two parties. But again the password suffers from offline dictionary attack. In this, a PicPass Protocol i.e. picture is used as a password to make an agreement between two parties. The protocol contains two function i.e. picture function as well as distortion function is used to make picture in a compact size and then it is sent to receiver. Firstly the sender encrypts the Plain Text using Secret Picture and creates the Cipher Text using Symmetric key cryptography. Then the Secret Picture will be encrypted by covered picture resulting into Encrypted Picture. Now the Cipher Text and Encrypted Picture will be placed into digital envelope and then the envelope will be send to the receiver. The receiver will receive the digital envelope, open it and then decrypt the Encrypted Picture using his Key Picture. This will result the receiver to get the Secret Picture. Now the receiver will open the Cipher Text using the Secret Picture and get the Plain Text. In between if any person wants to predict the Encrypted Picture then he cannot guess as the picture will only be decrypted using the Secret Key which will be only with the receiver. So in this dissertation, a picture is used as a password to authenticate key exchange is that gives practical solution against offline dictionary attacks only by using both private and public key cryptography.