الفهرس 
Overview of CryptographyOnly 14 pages are availabe for public view
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Abstract
Nowadays, computers and network became targets of computer crimes, which can result in loss of productivity, competitor advantage, theft of corporate of military, industrial, financial or business information, and stealing of research data. This thesis introduces two cryptosystems to provide privacy and confidentiality of data communication over an insecure channel like computer networks, satellite data linking (up and down), and telephone line.
The importance of multimedia security is becoming more and more important with the continuous increment in digital communication on the internet. The increasing use of audio and video in a wide range of application security and privacy issues to serious attention. With the advancement of both computer and internet technology, multimedia data, such as images, audio, videos, are being used more and more widely. In order to maintain privacy or security, sensitive data needs to be protected before transmission or distribution.
The main purpose of the presented study is to establish a secure way by implementing a cryptographic module to deal with the exchanged multimedia files via insecure communication channels using a symmetric key which is generated by A sophisticated mathematical way. Both the sender and receiver share a single key. The sender uses this key to encrypt plaintext and send the ciphertext to the receiver. On the other side the receiver applies the same key to decrypt the multimedia and recover the plaintext.
The information security uses cryptography on several levels. The information cannot be read without a key to decrypt it. The information maintains its integrity during transmit and while being stored. Cryptography also aids in nonrepudiation. This means that the sender and the delivery of a message can be verified. This module was tested using many image and text files and it was proved to be strong and secured.