安全通信系统OpenSSL服务器和客户端

1. 环境配置
2. SSL的初始化

                   这一步主要使用OpenSSL提供的函数设置算法、证书等，一般步骤都固定了的，初始化流程示意图如下所示：

                                                            

                                                                             SSL初始化流程图

                    主要代码为：

SSL_load_error_strings(); /*为打印调试信息作准备*/
OpenSSL_add_ssl_algorithms(); /*初始化*/

//meth = TLSv1_server_method(); /*采用什么协议(SSLv2/SSLv3/TLSv1)在此指定*/
//注意这里是server，客户端那里会是client
ctx = SSL_CTX_new (TLSv1_server_method()); 
CHK_NULL(ctx);

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

if (SSL_CTX_use_certificate_file(ctx, CERTF, SSL_FILETYPE_PEM) <= 0) {
	ERR_print_errors_fp(stderr);
	getchar();
	exit(3);
}

if (SSL_CTX_use_PrivateKey_file(ctx, KEYF, SSL_FILETYPE_PEM) <= 0) {
	ERR_print_errors_fp(stdout);
	getchar();
	exit(4);
}

if (!SSL_CTX_check_private_key(ctx)) {
	printf("Private key does not match the certificate public keyn");
	getchar();
	exit(5);
}


SSL_CTX_set_cipher_list(ctx,"RC4-MD5"); 

          3.SSL连接通信

              建立TCP套接字，并且进入监听，当接收到客户端连接请求后，使用accept建立和客户端通信的套接字s，从初始化的SSL_CTX创建一个SSL，将该SSL和与客户端通信的套接字s绑定，然后使用SSL_accept建立和客户端的SSL连接，如果建立成功就可以检查客户端的证书并获取客户端的证书信息，实现相互认证。之后，可以使用异步通信机制处理该SSL连接的消息。原理图如下图所示：

           

控制台的非异步通信的SSL通信代码如下所示。(非异步通信的代码原理看起来原理更好理解)

服务器端代码

//创建监听套接字
sListen = socket (AF_INET, SOCK_STREAM, 0); 
if(sListen == INVALID_SOCKET)
{
	cout << "监听套接字创建失败" << endl;
	exit(0);
}
//创建地址
sockaddr_in sin = {0};
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = INADDR_ANY;
sin.sin_port = htons (PORT); 

//套接字绑定
err = bind(sListen, (struct sockaddr*) &sin,sizeof(sin)); 
if(err == -1)
{
	cout << "监听套接字绑定失败" << endl;
	exit(0);
}

/*接受TCP链接*/
err = listen (sListen, 5); 
if(err == -1)
{
	cout << "监听套接字开启监听失败" << endl;
	exit(0);
}

//接受客户端连接
SOCKET sd = accept(sListen, (struct sockaddr *)&sa_cli, (socklen_t*)&client_len);

if(err == -1)
{
	cout << "监听套接字accept失败" << endl;
	exit(0);
}
closesocket (sListen);


/*TCP连接已建立,进行服务端的SSL过程. */
cout << "TCP连接建立，创建SSL连接中....\n" << endl;
//从初始化的ctx新建SSL
ssl = SSL_new (ctx); 
if(ssl == NULL)
{
	cout << "SSL创建失败" << endl;
	exit(0);
}
//套接字和SSL绑定
SSL_set_fd (ssl, sd);
//SSL连接建立
err = SSL_accept (ssl);
if(err == -1)
{
	cout << "创建SSL连接失败" << endl;
	exit(0);
}
else
{
	cout << "创建SSL连接成功" << endl;
	exit(0);
}

/*打印所有加密算法的信息(可选)*/
cout << "SSL连接算法信息:" << SL_get_cipher (ssl) << endl;

/*得到服务端的证书并打印些信息(可选) */
client_cert = SSL_get_peer_certificate (ssl);
if (client_cert != NULL) {
	cout << "客户端证书:" << endl;
	
	cout << "subject:" << X509_get_subject_name (client_cert), 0, 0) << endl;
	

	cout << "issuer:" << X509_NAME_oneline (X509_get_issuer_name (client_cert),0,0) << endl;
	CHK_NULL(str);
	X509_free (client_cert);/*如不再需要,需将证书释放 */
}
else cout << "客户端没有证书信息！" << endl; //客户端认证失败

//SSL通信，用SSL_write,SSL_read代替send和recv
while(true)
{	
	//接收消息
	err = SSL_read (ssl, buf, sizeof(buf) - 1); 
	if(err == -1)
	{
		cout << "SSL_read接收消息失败" << endl;
		exit(0);
	}
	buf[err] = '\0';
	cout << "【客户端】:" << buf << endl;

	cin >> buf;
	//发送消息
	err = SSL_write(ssl, buf, strlen(ssl));
	if(err == -1)
	{
		cout << "SSL_write发送消息失败" << endl;
		exit(0);
	}
	cout << "【服务器】:" << buf << endl;
}

//关闭套接字和ssl
shutdown (sd,2);
SSL_free (ssl);
SSL_CTX_free (ctx);

客户端代码

//
#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"

#pragma comment(lib, "libeay32.lib")
#pragma comment(lib, "ssleay32.lib")

/*所有需要的参数信息都在此处以#define的形式提供*/

#define CERTF "C:\\client.crt" /*服务端的证书(需经CA签名)*/
#define KEYF "C:\\client.key" /*服务端的私钥(建议加密存储)*/
#define CACERT "C:\\ca.crt" /*CA 的证书*/
#define PORT 7758 /*服务端的端口*/

int main ()
{
	int err;

	int sd;
	struct sockaddr_in sa;
	SSL_CTX* ctx;
	SSL* ssl;
	X509* server_cert;
	char* str;
	char buf [4096] = {0};
	char szMsg[4096] = {0}; 
	//SSL_METHOD *meth;
	int seed_int[100]; /*存放随机序列*/

	WSADATA wsaData;

	if(WSAStartup(MAKEWORD(2,2),&wsaData) != 0){
		printf("WSAStartup()fail:%d\n",GetLastError());
		return -1;
	} 

	OpenSSL_add_ssl_algorithms(); /*初始化*/
	SSL_load_error_strings(); /*为打印调试信息作准备*/

	//注意这里是client和和服务器不同
	ctx = SSL_CTX_new (TLSv1_client_method()); 
	CHK_NULL(ctx);

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


	if (SSL_CTX_use_certificate_file(ctx, CERTF, SSL_FILETYPE_PEM) <= 0) 
	{
		cout << "客户端证书检查失败！" << endl;
		exit(0);
	}

	if (SSL_CTX_use_PrivateKey_file(ctx, KEYF, SSL_FILETYPE_PEM) <= 0) 
	{
		cout << "客户端key检查失败！" << endl;
		exit(0);
	}

	if (!SSL_CTX_check_private_key(ctx)) 
	{
		cout << "客户端证书和key不匹配！" << endl;
		exit(0);
	}

	/*构建随机数生成机制,WIN32平台必需*/
	srand( (unsigned)time( NULL ) );
	for( int i = 0; i < 100;i++ ) seed_int[i] = rand();

	RAND_seed(seed_int, sizeof(seed_int));
	
	//创建TCP连接请求
	sd = socket (AF_INET, SOCK_STREAM, 0); 
	if(sd == INVALID_SOCKET)
	{
		cout << "套接字创建失败！" << endl;
		exit(0);
	}
	memset(&sa,'\0', sizeof(sa));
	sa.sin_family = AF_INET;
	sa.sin_addr.s_addr = inet_addr ("127.0.0.1"); 
	sa.sin_port = htons (PORT); /* Server Port number */

	//TCP连接
	err = connect(sd, (struct sockaddr*) &sa,
	if(err == -1)
	{
		cout << "TCP连接失败！" << endl;
		exit(0);
	}
	else
	{
		cout << "SSL连接成功！" << endl;
		exit(0);
	}
	//SSL连接
	//新建SSL
	ssl = SSL_new (ctx); 
	if(ssl == NULL)
	{
		cout << "新建SSL失败!" << endl;
		exit(0);
	}
	//套接字和SSL绑定
	SSL_set_fd (ssl, sd);
	//SLL连接
	err = SSL_connect (ssl);
	if(err == -1)
	{
		cout << "SSL连接失败" << endl;
		exit(0);
	}
	else
	{
		cout << "SSL连接成功" << endl;
		exit(0);
	}
	//打印连接信息
	cout << "SSL连接算法信息：" << SSL_get_cipher (ssl) << endl;

	/*得到服务端的证书并打印些信息(可选) */
	server_cert = SSL_get_peer_certificate (ssl);
	if (server_cert != NULL) {
		cout << "服务器证书:" << endl;
		
		cout << "subject:" << X509_get_subject_name (server_cert), 0, 0) << endl;
		

		cout << "issuer:" << X509_NAME_oneline (X509_get_issuer_name (server_cert),0,0) << endl;
		CHK_NULL(str);
		X509_free (server_cert);/*如不再需要,需将证书释放 */
	}
	else cout << "服务器没有证书信息！" << endl; //服务器端认证失败

	//SSL通信，用SSL_write,SSL_read代替send和recv
	while(true)
	{	
		cout << "请输入要发送的消息:";
		cin >> buf;
		//发送消息
		err = SSL_write(ssl, buf, strlen(ssl));
		if(err == -1)
		{
			cout << "SSL_write发送消息失败" << endl;
			exit(0);
		}
		cout << "【客户端】:" << buf << endl;
		//接收消息
		err = SSL_read (ssl, buf, sizeof(buf) - 1); 
		if(err == -1)
		{
			cout << "SSL_read接收消息失败" << endl;
			exit(0);
		}
		buf[err] = '\0';
		cout << "【服务器】:" << buf << endl;
	}

	/* 收尾工作 */
	SSL_shutdown (ssl);
	shutdown (sd,2);
	SSL_free (ssl);
	SSL_CTX_free (ctx);

	return 0;
}