| To realize data confidentiality on the network card is studied in this thesis. Recently, network security has been the obstacle for the development of network. Encryption is one of the basic security methods of data confidentiality. But encrypting packet with software not only occupies the resource of CPU, but also degrades the performance of network. Thus the study of the realization of encryption with hardware in the network card is very important. The thesis at first gives the basic concept and principle of computer network, and summarizes it's Standard Reference Model, and then gives the basic knowledge of cryptography and IP Security protocol. In the part of cryptography which the IP Security protocol usually uses, the public key algorithm and symmetry encryption algorithm are first studied, and the widely used representative algorithms DES and RSA are analyzed. Then the hash algorithm of MD5, which is often used in the digital signature, is introduced and implemented with C language. In the part of IP Security protocol, the principles of Authentication Header Protocol and Encapsulation Security Protocol are studied, and emphasis is put on the principle of Internet Key Exchange Protocol. It's potential problem is improved, then source code of IP Security protocol in Linux is analyzed. In the last part of this thesis, the composition of network card is introduced and the function of its model is discussed. The process of data sent and received on the network interface controller is analyzed, and the solution to the security problem in the network card is provided. This assure to transfer the data on the network safely. |
