TLS协议
TLS简介
TLS协议基于面向连接的TCP协议,它可被看作由两个主要部分组成:TLS记录协议(TLS Record Protocol)和TLS握手协议(TLS Handshake Protocol)。它可以实现传输应用数据前的通信双方身份的认证,加密套件(对称加密算法,签名算法等)的协商,会话**的协商,以及握手完成后的数据加密、压缩传输、以及数据完整性的校验。
TLS握手具体的过程
1.TCP三次握手
TCP的三次握手过程,建立TCP连接。
2.TLS握手过程
(1)TLS的握手是建立在TCP连接之上的。
(2)客户端向服务器发送client hello数据包。
在client hello数据包中说明了客户端使用的协议版本号、随机数、加密套件以及其他的扩展。wireshark抓包结果如下图:
(3)服务器收到client hello后向客户端发送server hello数据包。
在server hello中包含了协议版本号、随机数、服务器选择的加密套件以及其他的扩展。wireshark抓包结果如下图:
(4)服务器向客户端发送证书。wireshark抓包结果如下图:
(5)服务器向客户端发送server key exchange,其中包含了pubkey,wireshark抓包结果如下图:
(6)服务器向客户端发送server hello done,wireshark抓包结果如下图:
(7)客户端向服务器发送client key exchange、change cipher spec,wireshark抓包结果如下图:
(8)服务器向客户端发送new session ticket,wireshark抓包结果如下图:
(9)服务器向客户端发送change cipher spec, wireshark抓包结果如下图:
(10)服务器向客户端发送hello request, wireshark抓包结果如下图:
服务器向客户端发送change cipher spec, wireshark抓包结果如下图:
(11)客户端向服务器发送数据,wireshark抓包结果如下图:
openssl实现TLS
1.证书准备
在tls的通信中可以设置,双方认证和单向认证。如果需要双向的认证,需要有通信双方的证书。通过openssl的提供的应用程序功能可以搭建自己的简单的CA,从而颁发证书。
2.基于openssl的TLS实现
客户端程序
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <resolv.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#define MAXBUF 1024
#define CA_FILE "/home/xx/桌面/Untitled Folder/CA/ca.crt"
#define CLIENT_KEY "/home/xx/桌面/Untitled Folder/Client/client.key"
#define CLIENT_CERT "/home/xx/桌面/Untitled Folder/Client/client.crt"
/*打印对方主体和颁发者信息*/
void ShowCerts(SSL * ssl)
{
X509 *cert;
char *line;
cert = SSL_get_peer_certificate(ssl);
if (cert != NULL) {
printf("数字证书信息:\n");
line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
printf("证书: %s\n", line);
free(line);
line = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
printf("颁发者: %s\n", line);
free(line);
X509_free(cert);
} else {
printf("无证书信息!\n");
}
}
int main(int argc, char **argv)
{
int sockfd, len;
long int result = LONG_MAX;
struct sockaddr_in dest;
char buffer[MAXBUF + 1];
SSL_CTX *ctx;
SSL *ssl;
const SSL_METHOD *method;
/*初始化工作*/
SSL_library_init();
SSL_load_error_strings();
OpenSSL_add_all_algorithms();
method = TLSv1_2_client_method();
ctx = SSL_CTX_new(method);
if (!ctx) {
printf("create ctx is failed.\n");
}
/*设置会话的握手方式*/
SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, 0);
/*加载CA FILE*/
if (SSL_CTX_load_verify_locations(ctx, CA_FILE, 0) != 1) {
SSL_CTX_free(ctx);
printf("Failed to load CA file %s", CA_FILE);
}
if (SSL_CTX_set_default_verify_paths(ctx) != 1) {
SSL_CTX_free(ctx);
printf("Call to SSL_CTX_set_default_verify_paths failed");
}
/*设置证书链的最大深度*/
SSL_CTX_set_verify_depth(ctx,1);
/*加载客户端证书*/
if (SSL_CTX_use_certificate_file(ctx, CLIENT_CERT, SSL_FILETYPE_PEM) != 1) {
SSL_CTX_free(ctx);
printf("Failed to load client certificate from %s", CLIENT_KEY);
}
/*加载客户端私钥*/
if (SSL_CTX_use_PrivateKey_file(ctx, CLIENT_KEY, SSL_FILETYPE_PEM) != 1) {
SSL_CTX_free(ctx);
printf("Failed to load client private key from %s", CLIENT_KEY);
}
/*验证私钥*/
if (SSL_CTX_check_private_key(ctx) != 1) {
SSL_CTX_free(ctx);
printf("SSL_CTX_check_private_key failed");
}
/*处理握手多次*/
SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
/*创建tcp套接字*/
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){
perror("Socket");
exit(errno);
}
bzero(&dest, sizeof(dest));
dest.sin_family = AF_INET;
dest.sin_port = htons(atoi(argv[2]));
if (inet_aton(argv[1], (struct in_addr *) &dest.sin_addr.s_addr) == 0{
perror(argv[1]);
exit(errno);
}
if (connect(sockfd, (struct sockaddr *) &dest, sizeof(dest)) != 0) {
perror("Connect ");
exit(errno);
}
/*创建SSL*/
ssl = SSL_new(ctx);
if (ssl == NULL) {
printf("SSL_new error.\n");
}
/*将fd添加到ssl层*/
SSL_set_fd(ssl, sockfd);
/*TLS握手*/
if (SSL_connect(ssl) == -1) {
printf("SSL_connect fail.\n");
ERR_print_errors_fp(stderr);
} else {
printf("Connected with %s encryption\n", SSL_get_cipher(ssl));
ShowCerts(ssl);
}
result=SSL_get_verify_result(ssl);
if(result != X509_V_OK)
{
printf("There are some mistakes in verification:error %ld\n",result);
}
else
{
printf("Verification success!\n");
}
bzero(buffer, MAXBUF + 1);
len = SSL_read(ssl, buffer, MAXBUF);
if (len > 0) {
printf("接收消息成功:'%s',共%d个字节的数据\n", buffer, len);
} else {
printf("消息接收失败!错误代码是%d,错误信息是'%s'\n", errno, strerror(errno));
goto exit;
}
bzero(buffer, MAXBUF + 1);
strcpy(buffer, "from client->server");
len = SSL_write(ssl, buffer, strlen(buffer));
if (len < 0) {
printf("消息'%s'发送失败!错误代码是%d,错误信息是'%s'\n", buffer, errno, strerror(errno));
} else {
printf("消息'%s'发送成功,共发送了%d个字节!\n", buffer, len);
}
exit
SSL_shutdown(ssl);
SSL_free(ssl);
close(sockfd);
SSL_CTX_free(ctx);
return 0;
}
服务器端程序
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#define MAXBUF 1024
#define CA_FILE "/home/xx/桌面/Untitled Folder/CA/ca.crt"
#define SERVER_KEY "/home/xx/桌面/Untitled Folder/Server/server.key"
#define SERVER_CERT "/home/xx/桌面/Untitled Folder/Server/server.crt"
void ShowCerts(SSL * ssl)
{
X509 *cert;
char *line;
cert = SSL_get_peer_certificate(ssl);
if (cert != NULL) {
printf("num cert messsage:\n");
line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
printf("cert: %s\n", line);
free(line);
line = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
printf("Issuer: %s\n", line);
free(line);
X509_free(cert);
} else
printf("no cert message \n");
}
int main(int argc, char **argv)
{
int sockfd, new_fd;
int reuse = 0;
long int result = LONG_MAX;
socklen_t len;
struct sockaddr_in my_addr, their_addr;
unsigned int myport, lisnum;
char buf[MAXBUF + 1];
SSL_CTX *ctx;
const SSL_METHOD *method;
if (argv[1]) {
myport = atoi(argv[1]);
} else {
myport = 7838;
}
if (argv[2]) {
lisnum = atoi(argv[2]);
} else {
lisnum = 2;
}
SSL_library_init();
OpenSSL_add_all_algorithms();
SSL_load_error_strings();
method = TLSv1_2_server_method();
ctx = SSL_CTX_new(method);
if (ctx == NULL) {
ERR_print_errors_fp(stdout);
exit(1);
}
/*设置认证方式,要求认证客户端,实现双向认证*/
SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, 0);
/*加载CA FILE*/
if (SSL_CTX_load_verify_locations(ctx, CA_FILE, 0) != 1) {
SSL_CTX_free(ctx);
printf("Failed to load CA file %s", CA_FILE);
}
/*加载服务端证书*/
if (SSL_CTX_use_certificate_file(ctx, SERVER_CERT, SSL_FILETYPE_PEM) <= 0) {
ERR_print_errors_fp(stdout);
exit(1);
}
/*加载服务端私钥*/
if (SSL_CTX_use_PrivateKey_file(ctx, SERVER_KEY, SSL_FILETYPE_PEM) <= 0) {
printf("use private key fail.\n");
ERR_print_errors_fp(stdout);
exit(1);
}
/*验证私钥*/
if (!SSL_CTX_check_private_key(ctx)) {
ERR_print_errors_fp(stdout);
exit(1);
}
//处理握手多次
SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1) {
perror("socket");
exit(1);
} else {
printf("socket created\n");
}
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) < 0){
printf("setsockopet error\n");
return -1;
}
bzero(&my_addr, sizeof(my_addr));
my_addr.sin_family = PF_INET;
my_addr.sin_port = htons(myport);
my_addr.sin_addr.s_addr = INADDR_ANY;
if (bind(sockfd, (struct sockaddr *) &my_addr, sizeof(struct sockaddr)) == -1) {
perror("bind");
exit(1);
}
printf("Server bind success.\n");
if (listen(sockfd, lisnum) == -1) {
perror("listen");
exit(1);
}
printf("Server begin to listen\n");
while (1) {
SSL *ssl;
len = sizeof(struct sockaddr);
if ((new_fd = accept(sockfd, (struct sockaddr *) &their_addr, &len)) == -1) {
perror("accept");
exit(errno);
}
printf("Server: receive a connection from %s, port %d, socket %d\n", inet_ntoa(their_addr.sin_addr), ntohs(their_addr.sin_port), new_fd);
ssl = SSL_new(ctx);
if (ssl == NULL) {
printf("SSL_new error.\n");
}
SSL_set_fd(ssl, new_fd);
if (SSL_accept(ssl) == -1) {
perror("accept");
ERR_print_errors_fp(stderr);
close(new_fd);
break;
}
printf("Server with %s encryption\n", SSL_get_cipher(ssl));
ShowCerts(ssl);
result=SSL_get_verify_result(ssl);
if(result != X509_V_OK)
{
printf("There are some mistakes in verification:error %ld\n",result);
}
else
{
printf("Verification success!\n");
}
bzero(buf, MAXBUF + 1);
strcpy(buf, "server->client");
len = SSL_write(ssl, buf, strlen(buf));
if (len <= 0) {
printf("消息'%s'发送失败!错误代码是%d,错误信息是'%s'\n", buf, errno, strerror(errno));
goto exit;
} else {
printf("消息'%s'发送成功,共发送了%d个字节!\n", buf, len);
}
bzero(buf, MAXBUF + 1);
len = SSL_read(ssl, buf, MAXBUF);
if (len > 0) {
printf("接收消息成功:'%s',共%d个字节的数据\n", buf, len);
} else {
printf("消息接收失败!错误代码是%d,错误信息是'%s'\n", errno, strerror(errno));
}
exit:
SSL_shutdown(ssl);
SSL_free(ssl);
close(new_fd);
}
close(sockfd);
SSL_CTX_free(ctx);
return 0;
}