利用OpenSSL建立SSL安全通信(C/S)(一）

/******************************************************************************************

*SSL/TLS客户端程序WIN32版(以demos/cli.cpp为基础)

*需要用到动态连接库libeay32.dll,ssleay.dll,

*同时在setting中加入ws2_32.lib libeay32.lib ssleay32.lib,

*以上库文件在编译openssl后可在out32dll目录下找到,

*所需证书文件请参照<<利用Openssl生成证书文件>>自行生成*/

******************************************************************************************/

#include <stdio.h>

#include <stdlib.h>

#include <memory.h>

#include <errno.h>

#include <sys/types.h>

#include <winsock2.h>

#include "openssl/rsa.h"

#include "openssl/crypto.h"

#include "openssl/x509.h"

#include "openssl/pem.h"

#include "openssl/ssl.h"

#include "openssl/err.h"

#include "openssl/rand.h"

/*所有需要的参数信息都在此处以#define的形式提供*/

#define CERTF "client.crt" /*客户端的证书(需经CA签名)*/

#define KEYF "client.key" /*客户端的私钥(建议加密存储)*/

#define CACERT "ca.crt" /*CA 的证书*/

#define PORT 1111 /*服务端的端口*/

#define SERVER_ADDR "127.0.0.1" /*服务段的IP地址*/

//检查错误

#define CHK_NULL(x) if ((x)==NULL) { exit (-1); }

#define CHK_ERR(err,s) if ((err)==-1) { perror(s); exit(-2); }

#define CHK_SSL(err) if ((err)==-1) { ERR_print_errors_fp(stderr); exit(-3); }

int main (void)

{

int err;

int sd;

struct sockaddr_in sa;

SSL_CTX* ctx;

SSL* ssl;

X509* server_cert;

char* str;

char buf [4096];

SSL_METHOD *meth;

int seed_int[100]; /*存放随机序列*/

WSADATA wsaData;

//获取SOCKET版本(2.2)

if(WSAStartup(MAKEWORD(2,2),&wsaData) != 0)

{

printf("WSAStartup()fail:%d/n",GetLastError());

return -1;

}

OpenSSL_add_ssl_algorithms(); /*初始化,加载算法*/

SSL_load_error_strings(); /*加载错误信息,为打印调试信息作准备*/

meth = TLSv1_client_method(); /*采用什么协议(SSLv2/SSLv3/TLSv1)在此指定*/

ctx = SSL_CTX_new (meth);

CHK_NULL(ctx);

SSL_CTX_set_verify(ctx,SSL_VERIFY_PEER,NULL); /*验证对方*/

SSL_CTX_load_verify_locations(ctx,CACERT,NULL); /*若验证,则放置CA证书*/

//加载自己的证书client.crt

if (SSL_CTX_use_certificate_file(ctx, CERTF, SSL_FILETYPE_PEM) <= 0)

{

ERR_print_errors_fp(stderr);

exit(-2);

}

//加载自己的密钥文件client.key

if (SSL_CTX_use_PrivateKey_file(ctx, KEYF, SSL_FILETYPE_PEM) <= 0)

{

ERR_print_errors_fp(stderr);

exit(-3);

}

//验证验证密钥与证书是否配对

if (!SSL_CTX_check_private_key(ctx))

{

printf("Private key does not match the certificate public key/n");

exit(-4);

}

/*构建随机数生成机制,WIN32平台必需*/

srand( (unsigned)time( NULL ) );//以时间为种子

for( int i = 0; i < 100;i++ )

{

seed_int[i] = rand();

}

RAND_seed(seed_int, sizeof(seed_int));

/*以下是正常的TCP socket建立过程 .............................. */

printf("Begin tcp socket.../n");

sd = socket (AF_INET, SOCK_STREAM, 0); CHK_ERR(sd, "socket");

memset (&sa, '/0', sizeof(sa));

sa.sin_family = AF_INET;

sa.sin_addr.s_addr = inet_addr (SERVER_ADDR); /* Server IP */

sa.sin_port = htons (PORT); /* Server Port number */

err = connect(sd, (struct sockaddr*) &sa,sizeof(sa));

CHK_ERR(err, "connect");

/* TCP 连接已建立,开始 SSL 握手过程.......................... */

printf("Begin SSL negotiation n");

ssl = SSL_new (ctx);//建立SSL

CHK_NULL(ssl);

SSL_set_fd (ssl, sd);//关联SSL与SOCKET

err = SSL_connect (ssl);//用SSL连接Server

CHK_SSL(err);

/*打印所有加密算法的信息(可选)*/

printf ("SSL connection using %sn", SSL_get_cipher(ssl));

/*得到服务端的证书并打印些信息(可选) */

server_cert = SSL_get_peer_certificate(ssl);

CHK_NULL(server_cert);

printf ("Server certificate:/n");

str = X509_NAME_oneline(X509_get_subject_name(server_cert),0,0);

CHK_NULL(str);

printf ("t subject: %sn", str);

free (str);

str = X509_NAME_oneline (X509_get_issuer_name(server_cert),0,0);

CHK_NULL(str);

printf ("t issuer: %sn", str);

free (str);

X509_free(server_cert); /*如不需要,则将证书释放 */

/* 数据交换开始,用SSL_write,SSL_read代替write,read */

printf("Begin SSL data exchangen");

//发送消息

err =SSL_write(ssl,"Hello World!",strlen("Hello World!"));

CHK_SSL(err);

//接收消息

err = SSL_read (ssl, buf, sizeof(buf) - 1);

CHK_SSL(err);

buf[err] = '/0';

printf ("Got %d chars:'%s'n", err, buf);

SSL_shutdown (ssl); /* send SSL/TLS close_notify */

/* 收尾工作 */

shutdown (sd,2);

SSL_free (ssl);

SSL_CTX_free (ctx);

return 0;

}