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First network communication system analysis
一、網絡通信系統分析

Current network protocols are used in communication systems TCP / IP protocol , therefore, the network communication system, the data transmitted is encrypted session key of the application layer . The initial formation of the data will not only enable the encryption of data transmitted through the network more secure process , but also to avoid the transmission encryption process requires tedious . Thus , the design must first be encrypted during the entire network communication system to figure out , then the network system structure according to design the most appropriate for the network encryption system .
到現在為止網絡通信系統認為合適而使用的協議都是TCP/IP協議，因為這個，在對網絡通信系統中傳道輸送的數值施行加密時主要研討的就是對話應用層。在數值形成的起初就將其加密不止可以使數值在經過網絡傳道輸送的過程中更加的安全，還能夠防止在傳道輸送過程中需求施行加密的繁雜瑣碎。

Second, based on the data encrypted network communication system design
二、基于數值加密網絡通信系統的預設

To ensure the security of network communication system , data encryption has been widely put into use, but also to ensure the security of network communication system . However, the original data encrypted network communication system is inevitable , there are some loopholes, therefore , we are in the original data encrypted network communication system on a number of designs , ensuring data transfer more secure and reliable.
為了保證網絡通信系統的安全，數值加密已經存在廣泛的投入運用，也保證了網絡通信系統的安全。不過原有的數值加密網絡通信系統難以避免存在一點破綻，因為這個，我們就在原有的數值加密網絡通信系統向上行了一點預設，因此保證數值的傳道輸送更加的安全、靠得住。

( one ) encryption and decryption module design . This system is the symmetric ciphers and public key cryptography algorithm combine to make the advantages and disadvantages of the two combined to make up for their shortcomings . Symmetric ciphers with encryption speed, encryption strength characteristics of high efficiency to meet the large amounts of data encryption and decryption ; while the public key cryptography algorithm is slow with encryption , encryption , high strength, easy to manage key features , so that it can express keys for encryption . This will make up the symmetric key cryptography algorithm is not easy to pass the defect . Combination of both, the advantages of whichever make complementary , can be more easily encrypted network communication system .

( Two ) model with an external CBC triple IDEA algorithm encryption and decryption. Triple IDEA block cipher algorithm is in relatively good algorithm key length is 128bit, but it also has good resistance to the phase difference between the analysis and analytical, and easy hardware and software implementations.

Triple IDEA algorithm IDEA algorithm that is used under the action of the three key several times to encrypt a plaintext , the encryption algorithm used in the system must ensure that the three keys are independent . Assuming three keys are used to K1, K2, K3, the plaintext P, the ciphertext C, the key is encrypted with the EK after said decrypting means after the use DK . Therefore , the algorithm description of the process is as follows :

Encryption : C = EK3 (DK2 (EK1 (P))); decryption : P = DK1 (EK2 (DK3 (C)))
CBC is not an encryption algorithm, but the implementation of an algorithm is a cipher mode . Password mode will not damage the security of cryptographic algorithms , and applications in CBC mode is mainly in the plaintext before it is encrypted with the previous ciphertext XOR . In a group of plaintext block is encrypted later , the result will be stored in the feedback register inside , and then the next group when the plaintext block cipher , CBC mode will be the first of this group after the plaintext block with the previous ciphertext encrypted XOR or operation, and then save the results and the feedback register and turn it with the next set of XOR plaintext block , has been circulated to encrypt plaintext block end . CBC mode using such a method is intended primarily for the exact same message to different ciphertext encrypted messages , so you can avoid eavesdroppers way again using packet replay attack . Whole encryption process is not difficult to achieve , but must ensure that the key used to encrypt the mutually independent , and the system is the key used by the system generated random function .

Third, using the RSA algorithm for key encryption

RSA algorithm is the decomposition of large numbers of security and difficulty are closely related. Strike a key using the RSA algorithm method is as follows: First, we randomly choose two large prime numbers P and Q; then calculated by multiplying the two modulus, the two numbers were multiplied by subtracting a calculated the Euler function Φ (n); calculated Euler function and select its positive integers coprime d, which must satisfy gcd (d, Φ (n)) = 1 condition ; the final calculation of the key e, but it must satisfy the conditions d * e = 1mod (Φ (n)). These keys in e, n is open, and p, q, d is the secret , e is the public encryption key , d is the secret decryption key .

Fourth, the network communication system based on data encryption application

The encryption system is based on the Internet in C / S model of communication , it is mainly used in the model . It is mainly in the application layer for data encryption , authentication and digital signature or operation , and then the data sender is encrypted with a triple IDEA algorithm , the one-way hash function SHA-1 digital signature , and the triple of IDEA keys K1, K2, K3 and other information using the RSA encryption algorithm , the encryption is complete the final ciphertext to the recipient . The recipient receives the message will be in accordance with the sender encrypted manner to decrypt the data , get the sender to send the original, and then further verification. Thus, between the client and server can communicate normally carried out in order to protect the security of communication between the two .

Based on data encrypted network communication system in many areas can be used , it is mainly to avoid information being intercepted during transmission or tampered with, in the field need to use communication systems require the use of encryption systems , which can protect the network in information security. Network communication encryption system is an essential part of the system , but also network communication system and its role will be to play the most .

V. Conclusion
In the rapid development of the information age, network communication systems is very important , but also by a great deal of attention. In order to ensure the security of network communication system , research and the use of the encryption system , it is very necessary. We discussed in the text encryption system during the testing process does implement data encryption, and digital signature functions. The network communication system in constant development , the encryption system will also continue to develop . Encryption systems in the network communication system will also play out its role , and with the development of network communication system will provide better security.

References:
[ 1 ] Meng Yanhong , Qin Weijia , Xinyi Zhong based on data encrypted network communication system design and implementation [J]. Shenyang University of Technology , 2004,26 ( 1 ) :93 -95
[ 2 ] Xiamei Feng , Shi Hongbao based on data encrypted network communication system security model and design [J]. Computer Engineering, 2001,27 ( 10 ) :117 -126
[ 3 ] Wang Zhichao based on data encrypted network communications copper research [D]. ??Hebei University of Technology , 2006,11