Design And Implementation Of An Electronic Document Secure Transmission System

With the rapid development of computer network and the perfection of its technology, modern information technology has entered into a continuously changed age. As an important transmission medium, the Internet allows various electronic document such as text, music, picture, and video constantly produced and shared in the global world. Because of dynamic and openness characteristics of the Internet, the document is vulnerable to kinds of potential security threats in a practical application. How to ensure the security and privacy of the document has become a hotspot in the field of computer science.Based on the above demand, the thesis designed and realized an electronic document secure transmission system in C/S mode with the relevant technology of cryptography and network transmission. After analysis of the AES algorithm and the RSA algorithm, as well as synthesis of digital signature, the thesis proposed a hybrid encryption scheme based on the AES and RSA algorithm and designed a secure way of key management. Before transmission, the system generate the document’s digital signature firstly which stands for the sender’s identity. Next, the system encrypts the document via the AES algorithm and encrypts the AES session key via the RSA algorithm. Finally, the cipher and the encrypted AES key are combined and send to the receiver. After separating the AES key, the receiver decrypts the key and the cipher through the reverse order and then validates the digital signature. If the validation is successful, the receiver will save the plaintext; otherwise the document will be declined. Moreover, the system used the TCP protoctol to realize the network communication as well as designed the corresponding transport protocol and data format which can guarantee the document transmission is secure and ordered.On the basis of user requirement and system design, the thesis introduces the implementation of each fuction mode. According to the test in actual environment, the system has the basic function of safety transmission and achieve the expected target.