distribution. The public key encryption uses two keys in the encryption and decryption process, which is stronger and less likely to be breakthroughs, but it is slower than traditional encryption. As a result of these advantages and disadvantages it has become modern systems using both methods, where they use the traditional method of encryption and the exchange of a single secret key between the multicast parties carried out through the use of public key encryption method....[2] 4. Digital certificates:
network secutity, there are several problems that can be addressed such as integrity, data secrecy, digital signature problems and authentication. To provide a significant protection for the data,a well-established security control is Encryption. On the basis of this encryption, we would like to propose a digital signature authentication technique. In this paper, we are trying to solve the problem by considering a scheme which is shared secretly with digital signature protocols and authentication. For the
CHAPTER 1 INTRODUCTION 1.1 Cryptography The word cryptography is derived from the Greek words Cryptos meaning cover and grafia meaning writing [1] defining it as covered writing. In image cryptography the information is hidden exclusively in images. Cryptography is the art and science of secret communication .It is the practice of encoding/embedding secret information in a manner such that the existence of the information is invisible. The original files can be referred to as cover text, cover image
The so called Enigma machine, a electro-mechanical encryption machine developed by Arthur Sherbius at the end of the previous world war, made use of a substitution cypher. What made it almost impossible to crack was the fact that a mechanism inside the machine changed the substitution alphabet after every single letter. Its use on the other hand was very easy: the plaintext had to be typed on the keyboard of the machine to produce the ciphertext. If the recipient of the message entered the ciphertext