使用UDP服务器进行消息加密和解密-yiteyi-C++库

在使用UDP服务器的客户机-服务器通信期间，消息加密和解密的过程如下：

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客户端向服务器请求一个文件名。
服务器打开相应的文件，并使用数据报套接字发送该文件。
发送方发送带有固定长度密钥的加密文本（Xoring）。
接收方接收加密文本（密文）。
接收方使用相同的密钥（私钥）解密文件。

例子 :

Input :  file.txtOutput : ClientSide : Received from server:                       00 2C 28 28 2A 6E 3B 24 37 64 65 79 0A 00 00                       Decrypted message: Hello People          ServerSide : Encrypted message stored in file:                       00 2C 28 28 2A 6E 3B 24 37 64 65 79 0A 00

客户端程序 :

C

                           // Client side code                         
                           #include <netinet/in.h>                         
                           #include <stdio.h>                         
                           #include <string.h>                         
                           #include <sys/socket.h>                         
            
                           // Driver code                         
                           int                                        main()                         
                           {                         
                                                     int                                        clientSocket, portNum, nBytes;                         
                                                     char                                        file_buffer[3000], path[1024], buffer[3000];                         
            
                                                     // This key array stores the hidden key                         
                                                     char                                        const                                        key[3000] =                                        "HIDDENKEY"                                        ;                         
                                                     struct                                        sockaddr_in serverAddr;                         
                                                     socklen_t addr_size;                         
                                                     int                                        i;                         
                                                     clientSocket = socket(PF_INET, SOCK_DGRAM, 0);                         
            
                                                     serverAddr.sin_family = AF_INET;                         
                                                     serverAddr.sin_port = htons(5004);                         
                                                     serverAddr.sin_addr.s_addr = inet_addr(                                        "127.0.0.1"                                        );                         
                                                     memset                                        (serverAddr.sin_zero,                                        ' '                                        ,                                        sizeof                                        serverAddr.sin_zero);                         
            
                                                     addr_size =                                        sizeof                                        serverAddr;                         
            
                                                     while                                        (1) {                         
                                                     printf                                        (                                        "Specify file name: "                                        );                         
                                                     gets                                        (path);                         
            
                                                     // printf("%s", path);                         
                                                     FILE                                        * fp;                         
                                                     fp =                                        fopen                                        (path,                                        "r"                                        );                         
                                                     if                                        (fp == NULL) {                         
                                                     printf                                        (                                        "file does not exist"                                        );                         
                                                     }                         
            
                                                     fseek                                        (fp, 0, SEEK_END);                         
                                                     size_t                                        file_size =                                        ftell                                        (fp);                         
                                                     fseek                                        (fp, 0, SEEK_SET);                         
            
                                                     if                                        (                                        fread                                        (file_buffer, file_size, 1, fp) <= 0) {                         
                                                     printf                                        (                                        "unable to copy file into buffer"                                        );                         
                                                     exit                                        (1);                         
                                                     }                         
            
                                                     if                                        (sendto(clientSocket, file_buffer, 3000, 0, (                                        struct                                        sockaddr*)&serverAddr,                         
                                                     addr_size) < 0) {                         
                                                     printf                                        (                                        "error in sending the file"                                        );                         
                                                     exit                                        (1);                         
                                                     }                         
            
                                                     bzero(file_buffer,                                        sizeof                                        (file_buffer));                         
            
                                                     nBytes = recvfrom(clientSocket, buffer, 1024, 0, NULL, NULL);                         
            
                                                     printf                                        (                                        "Received from server: "                                        );                         
            
                                                     // printing some of the character to have a feel of encryption                         
                                                     for                                        (i = 0; i < 15; ++i)                         
                                                     printf                                        (                                        "%02X "                                        , buffer[i]);                         
                                                     printf                                        (                                        ""                                        );                         
            
                                                     char                                        x[3000];                         
                                                     for                                        (i = 0; i < nBytes - 1; ++i)                         
                                                     x[i] = (                                        char                                        )(buffer[i] ^ key[i]);                         
            
                                                     // printing some of the character to have a feel of decryption                         
                                                     printf                                        (                                        "Decrypted message: (First 15 characters)"                                        );                         
                                                     for                                        (i = 0; i < 11; ++i)                         
                                                     printf                                        (                                        "%c "                                        , x[i]);                         
            
                                                     printf                                        (                                        ""                                        );                         
                                                     }                         
            
                                                     return                                        0;                         
                           }                         

服务器端程序 :

C

                           // C server code                         
                           #include <memory.h>                         
                           #include <netinet/in.h>                         
                           #include <stdio.h>                         
                           #include <stdlib.h>                         
                           #include <string.h>                         
                           #include <sys/socket.h>                         
            
                           // Driver code                         
                           int                                        main()                         
                           {                         
                                                     int                                        udpSocket, nBytes;                         
                                                     char                                        buffer[3000], xor[3000];                         
                                                     char                                        const                                        key[1024] =                                        "HIDDENKEY"                                        ;                         
                                                     struct                                        sockaddr_in serverAddr, clientAddr;                         
                                                     struct                                        sockaddr_storage serverStorage;                         
                                                     socklen_t addr_size, client_addr_size;                         
                                                     int                                        i;                         
            
                                                     udpSocket = socket(PF_INET, SOCK_DGRAM, 0);                         
            
                                                     serverAddr.sin_family = AF_INET;                         
                                                     serverAddr.sin_port = htons(5004);                         
                                                     serverAddr.sin_addr.s_addr = inet_addr(                                        "127.0.0.1"                                        );                         
                                                     memset                                        (serverAddr.sin_zero,                                        ' '                                        ,                                        sizeof                                        serverAddr.sin_zero);                         
            
                                                     bind(udpSocket, (                                        struct                                        sockaddr*)&serverAddr,                                        sizeof                                        (serverAddr));                         
            
                                                     addr_size =                                        sizeof                                        serverStorage;                         
                                                     puts                                        (                                        "Waiting for client :"                                        );                         
                                                     int                                        count = 0;                         
            
                                                     while                                        (1) {                         
                                                     nBytes = recvfrom(udpSocket, buffer, 3000, 0, (                                        struct                                        sockaddr*)&serverStorage,                         
                                                     &addr_size);                         
                                                     printf                                        (                                        "Message no : %d"                                        , ++count);                         
            
                                                     for                                        (i = 0; i < nBytes - 1; i++) {                         
                                                     if                                        (buffer[i] !=                                        ''                                        )                         
                                                     xor[i] = (                                        char                                        )(buffer[i] ^ key[i]);                         
                                                     else                         
                                                     xor[i] = buffer[i];                         
                                                     }                         
            
                                                     printf                                        (                                        "Encrypted message stored in file : (First 15 characters)"                                        );                         
            
                                                     // printing some of the character to have a feel of encryption                         
                                                     for                                        (i = 0; i < 15; ++i)                         
                                                     printf                                        (                                        "%02X "                                        , xor[i]);                         
                                                     printf                                        (                                        ""                                        );                         
            
                                                     FILE                                        * fp;                         
                                                     fp =                                        fopen                                        (                                        "temp.txt"                                        ,                                        "w+"                                        );                         
            
                                                     for                                        (i = 0; i < nBytes - 1; i++) {                         
                                                     if                                        (xor[i] !=                                        ''                                        )                         
                                                     fprintf                                        (fp,                                        "%X"                                        , xor[i]);                         
                                                     else                         
                                                     fprintf                                        (fp,                                        "%c"                                        , xor[i]);                         
                                                     }                         
            
                                                     fclose                                        (fp);                         
                                                     sendto(udpSocket, xor, nBytes, 0, (                                        struct                                        sockaddr*)&serverStorage,                         
                                                     addr_size);                         
                                                     }                         
            
                                                     return                                        0;                         
                           }                         

输出 :

图片[1]-使用UDP服务器进行消息加密和解密-yiteyi-C++库

图片[2]-使用UDP服务器进行消息加密和解密-yiteyi-C++库

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