c - 如何在 c 中使用 openssl 创建聊天服务器

标签 c sockets ssl networking encryption

我想在 C 中使用 openssl 创建一个加密的聊天服务器，所以从以下位置获取了代码:http://simplestcodings.blogspot.in/2010/08/secure-server-client-using-openssl-in-c.html

我想将此代码转换为并发聊天服务器，但我该怎么做呢？

当我尝试将客户端与服务器连接时，它只是显示:

在服务器端:

Connection: 127.0.0.1:34902
No certificates.
Client msg: "Hello???"

在客户端:

Connected with AES256-GCM-SHA384 encryption
Server certificates:
Subject: /C=IN/ST=UK/L=DDN/O=UPES/OU=IT/CN=KAVIN/emailAddress=kavin_sharma@yahoo.com
Issuer: /C=IN/ST=UK/L=DDN/O=UPES/OU=IT/CN=KAVIN/emailAddress=kavin_sharma@yahoo.com
Received: "<html><body><pre>Hello???</pre></body></html>

"

我想在客户端和服务器之间进行加密聊天？

服务器.c

#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <malloc.h>
#include <string.h>
#include <sys/socket.h>
#include <resolv.h>
#include <netdb.h>
#include <openssl/ssl.h>
#include <openssl/err.h>

#define FAIL    -1

int OpenConnection(const char *hostname, int port)
{   int sd;
    struct hostent *host;
    struct sockaddr_in addr;

    if ( (host = gethostbyname(hostname)) == NULL )
    {
        perror(hostname);
        abort();
    }
    sd = socket(PF_INET, SOCK_STREAM, 0);
    bzero(&addr, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = *(long*)(host->h_addr);
    if ( connect(sd, (struct sockaddr*)&addr, sizeof(addr)) != 0 )
    {
        close(sd);
        perror(hostname);
        abort();
    }
    return sd;
}

SSL_CTX* InitCTX(void)
{   SSL_METHOD *method;
    SSL_CTX *ctx;

    OpenSSL_add_all_algorithms();  /* Load cryptos, et.al. */
    SSL_load_error_strings();   /* Bring in and register error messages */
    method = TLSv1_2_client_method();  /* Create new client-method instance */
    ctx = SSL_CTX_new(method);   /* Create new context */
    if ( ctx == NULL )
    {
        ERR_print_errors_fp(stderr);
        abort();
    }
    return ctx;
}

void ShowCerts(SSL* ssl)
{   X509 *cert;
    char *line;

    cert = SSL_get_peer_certificate(ssl); /* get the server's certificate */
    if ( cert != NULL )
    {
        printf("Server certificates:\n");
        line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
        printf("Subject: %s\n", line);
        free(line);       /* free the malloc'ed string */
        line = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
        printf("Issuer: %s\n", line);
        free(line);       /* free the malloc'ed string */
        X509_free(cert);     /* free the malloc'ed certificate copy */
    }
    else
        printf("Info: No client certificates configured.\n");
}

int main(int count, char *strings[])
{   SSL_CTX *ctx;
    int server;
    SSL *ssl;
    char buf[1024];
    int bytes;
    char *hostname, *portnum;

    if ( count != 3 )
    {
        printf("usage: %s <hostname> <portnum>\n", strings[0]);
        exit(0);
    }
    SSL_library_init();
    hostname=strings[1];
    portnum=strings[2];

    ctx = InitCTX();
    server = OpenConnection(hostname, atoi(portnum));
    ssl = SSL_new(ctx);      /* create new SSL connection state */
    SSL_set_fd(ssl, server);    /* attach the socket descriptor */
    if ( SSL_connect(ssl) == FAIL )   /* perform the connection */
        ERR_print_errors_fp(stderr);
    else

    {   char *msg = "Hello???";

        printf("Connected with %s encryption\n", SSL_get_cipher(ssl));
        ShowCerts(ssl);
        /* get any certs */
    while(1){
        SSL_write(ssl, msg, strlen(msg));   /* encrypt & send message */
        bytes = SSL_read(ssl, buf, sizeof(buf)); /* get reply & decrypt */
        buf[bytes] = 0;
        printf("Received: \"%s\"\n", buf);
        SSL_free(ssl);        /* release connection state */

}
   close(server);         /* close socket */
    SSL_CTX_free(ctx);        /* release context */

   return 0;
}

客户端.c

#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <malloc.h>
#include <string.h>
#include <sys/socket.h>
#include <resolv.h>
#include <netdb.h>
#include <openssl/ssl.h>
#include <openssl/err.h>

#define FAIL    -1

int OpenConnection(const char *hostname, int port)
{   int sd;
    struct hostent *host;
    struct sockaddr_in addr;

    if ( (host = gethostbyname(hostname)) == NULL )
    {
        perror(hostname);
        abort();
    }
    sd = socket(PF_INET, SOCK_STREAM, 0);
    bzero(&addr, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = *(long*)(host->h_addr);
    if ( connect(sd, (struct sockaddr*)&addr, sizeof(addr)) != 0 )
    {
        close(sd);
        perror(hostname);
        abort();
    }
    return sd;
}

SSL_CTX* InitCTX(void)
{   SSL_METHOD *method;
    SSL_CTX *ctx;

    OpenSSL_add_all_algorithms();  /* Load cryptos, et.al. */
    SSL_load_error_strings();   /* Bring in and register error messages */
    method = TLSv1_2_client_method();  /* Create new client-method instance */
    ctx = SSL_CTX_new(method);   /* Create new context */
    if ( ctx == NULL )
    {
        ERR_print_errors_fp(stderr);
        abort();
    }
    return ctx;
}

void ShowCerts(SSL* ssl)
{   X509 *cert;
    char *line;

    cert = SSL_get_peer_certificate(ssl); /* get the server's certificate */
    if ( cert != NULL )
    {
        printf("Server certificates:\n");
        line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
        printf("Subject: %s\n", line);
        free(line);       /* free the malloc'ed string */
        line = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
        printf("Issuer: %s\n", line);
        free(line);       /* free the malloc'ed string */
        X509_free(cert);     /* free the malloc'ed certificate copy */
    }
    else
        printf("Info: No client certificates configured.\n");
}

int main(int count, char *strings[])
{   SSL_CTX *ctx;
    int server;
    SSL *ssl;
    char buf[1024];
    int bytes;
    char *hostname, *portnum;

    if ( count != 3 )
    {
        printf("usage: %s <hostname> <portnum>\n", strings[0]);
        exit(0);
    }
    SSL_library_init();
    hostname=strings[1];
    portnum=strings[2];

    ctx = InitCTX();
    server = OpenConnection(hostname, atoi(portnum));
    ssl = SSL_new(ctx);      /* create new SSL connection state */
    SSL_set_fd(ssl, server);    /* attach the socket descriptor */
    if ( SSL_connect(ssl) == FAIL )   /* perform the connection */
        ERR_print_errors_fp(stderr);
    else

    {   char *msg = "Hello???";

        printf("Connected with %s encryption\n", SSL_get_cipher(ssl));
        ShowCerts(ssl);
        /* get any certs */
    while(1){
        SSL_write(ssl, msg, strlen(msg));   /* encrypt & send message */
        bytes = SSL_read(ssl, buf, sizeof(buf)); /* get reply & decrypt */
        buf[bytes] = 0;
        printf("Received: \"%s\"\n", buf);
        SSL_free(ssl);        /* release connection state */

}
   close(server);         /* close socket */
    SSL_CTX_free(ctx);        /* release context */

   return 0;
}

请评论将此代码转换为加密聊天服务器的代码更改

最佳答案

由于您已经在使用 SSL 功能，您的聊天程序实际上是安全的。但是从您的帖子来看，您似乎想要增强安全连接。 实现加解密可以试试，

//加密

AES_KEY encKey;
AES_set_encrypt_key(key, 128, &encKey);
AES_encrypt(text, out, &encKey);

//解密

AES_KEY decKey;
AES_set_decrypt_key(key,128,&decKey);
AES_decrypt(out, text, &decKey);

注意:key 应该是通用的

关于c - 如何在 c 中使用 openssl 创建聊天服务器，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/40812836/

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