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openssl demo
Raw
cli.cpp
/* cli.cpp - Minimal ssleay client for Unix
30.9.1996, Sampo Kellomaki <sampo@iki.fi> */
/* mangled to work with SSLeay-0.9.0b and OpenSSL 0.9.2b
Simplified to be even more minimal
12/98 - 4/99 Wade Scholine <wades@mail.cybg.com> */
#include <unistd.h>
#include <stdio.h>
#include <memory.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <openssl/crypto.h>
#include <openssl/x509.h>
#include <openssl/pem.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#define CERTF "client.crt"
#define KEYF "client.key"
#define CACERT "ca.crt"
#define CHK_NULL(x) if ((x)==NULL) exit (1)
#define CHK_ERR(err,s) if ((err)==-1) { perror(s); exit(1); }
#define CHK_SSL(err) if ((err)==-1) { ERR_print_errors_fp(stderr); exit(2); }
int main ()
{
int err;
int sd;
struct sockaddr_in sa;
SSL_CTX* ctx;
SSL* ssl;
X509* server_cert;
char* str;
char buf [4096];
SSL_METHOD *meth;
SSLeay_add_ssl_algorithms();
meth = SSLv23_client_method();
SSL_load_error_strings();
ctx = SSL_CTX_new (meth); CHK_NULL(ctx);
CHK_SSL(err);
SSL_CTX_set_verify(ctx,SSL_VERIFY_PEER,NULL);
SSL_CTX_load_verify_locations(ctx,CACERT,NULL);
if (SSL_CTX_use_certificate_file(ctx, CERTF, SSL_FILETYPE_PEM) <= 0) {
ERR_print_errors_fp(stderr);
exit(-2);
}
if (SSL_CTX_use_PrivateKey_file(ctx, KEYF, SSL_FILETYPE_PEM) <= 0) {
ERR_print_errors_fp(stderr);
exit(-3);
}
if (!SSL_CTX_check_private_key(ctx)) {
printf("Private key does not match the certificate public keyn");
exit(-4);
}
/* ----------------------------------------------- */
/* Create a socket and connect to server using normal socket calls. */
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 ("127.0.0.1"); /* Server IP */
sa.sin_port = htons (1111); /* Server Port number */
err = connect(sd, (struct sockaddr*) &sa,
sizeof(sa)); CHK_ERR(err, "connect");
/* ----------------------------------------------- */
/* Now we have TCP conncetion. Start SSL negotiation. */
ssl = SSL_new (ctx); CHK_NULL(ssl);
SSL_set_fd (ssl, sd);
err = SSL_connect (ssl); CHK_SSL(err);
/* Following two steps are optional and not required for
data exchange to be successful. */
/* Get the cipher - opt */
printf ("SSL connection using %s\n", SSL_get_cipher (ssl));
/* Get server's certificate (note: beware of dynamic allocation) - opt */
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: %s\n", str);
OPENSSL_free (str);
str = X509_NAME_oneline (X509_get_issuer_name (server_cert),0,0);
CHK_NULL(str);
printf ("\t issuer: %s\n", str);
OPENSSL_free (str);
/* We could do all sorts of certificate verification stuff here before
deallocating the certificate. */
X509_free (server_cert);
/* --------------------------------------------------- */
/* DATA EXCHANGE - Send a message and receive a reply. */
err = SSL_write (ssl, "Hello World!", strlen("Hello World!")); CHK_SSL(err);
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 */
/* Clean up. */
close (sd);
SSL_free (ssl);
SSL_CTX_free (ctx);
return 0;
}
/* EOF - cli.cpp */
Raw
Makefile
INC=/usr/local/ssl/include/
LIB=/usr/local/ssl/lib/
all:
g++ -I$(INC) -L$(LIB) cli.cpp -o cli -lssl -lcrypto -ldl -fpermissive
g++ -I$(INC) -L$(LIB) serv.cpp -o serv -lssl -lcrypto -ldl -fpermissive
clean:
rm -rf *~ cli serv
Raw
serv.cpp
/* serv.cpp - Minimal ssleay server for Unix
30.9.1996, Sampo Kellomaki <sampo@iki.fi> */
/* mangled to work with SSLeay-0.9.0b and OpenSSL 0.9.2b
Simplified to be even more minimal
12/98 - 4/99 Wade Scholine <wades@mail.cybg.com> */
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <memory.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <openssl/rsa.h> /* SSLeay stuff */
#include <openssl/crypto.h>
#include <openssl/x509.h>
#include <openssl/pem.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
/* define HOME to be dir for key and cert files... */
#define HOME "./"
/* Make these what you want for cert & key files */
#define CERTF HOME "server.crt"
#define KEYF HOME "server.key"
#define CACERT HOME "ca.crt"
#define CHK_NULL(x) if ((x)==NULL) exit (1)
#define CHK_ERR(err,s) if ((err)==-1) { perror(s); exit(1); }
#define CHK_SSL(err) if ((err)==-1) { ERR_print_errors_fp(stderr); exit(2); }
int main ()
{
int err;
int listen_sd;
int sd;
struct sockaddr_in sa_serv;
struct sockaddr_in sa_cli;
size_t client_len;
SSL_CTX* ctx;
SSL* ssl;
X509* client_cert;
char* str;
char buf [4096];
SSL_METHOD *meth;
/* SSL preliminaries. We keep the certificate and key with the context. */
SSL_load_error_strings();
SSLeay_add_ssl_algorithms();
meth = SSLv23_server_method();
ctx = SSL_CTX_new (meth);
if (!ctx) {
ERR_print_errors_fp(stderr);
exit(2);
}
SSL_CTX_set_verify(ctx,SSL_VERIFY_PEER,NULL); /* whether verify the certificate */
SSL_CTX_load_verify_locations(ctx,CACERT,NULL);
if (SSL_CTX_use_certificate_file(ctx, CERTF, SSL_FILETYPE_PEM) <= 0) {
ERR_print_errors_fp(stderr);
exit(3);
}
if (SSL_CTX_use_PrivateKey_file(ctx, KEYF, SSL_FILETYPE_PEM) <= 0) {
ERR_print_errors_fp(stderr);
exit(4);
}
if (!SSL_CTX_check_private_key(ctx)) {
fprintf(stderr,"Private key does not match the certificate public key\n");
exit(5);
}
/* ----------------------------------------------- */
/* Prepare TCP socket for receiving connections */
listen_sd = socket (AF_INET, SOCK_STREAM, 0); CHK_ERR(listen_sd, "socket");
memset (&sa_serv, '\0', sizeof(sa_serv));
sa_serv.sin_family = AF_INET;
sa_serv.sin_addr.s_addr = INADDR_ANY;
sa_serv.sin_port = htons (1111); /* Server Port number */
err = bind(listen_sd, (struct sockaddr*) &sa_serv,
sizeof (sa_serv)); CHK_ERR(err, "bind");
/* Receive a TCP connection. */
err = listen (listen_sd, 5); CHK_ERR(err, "listen");
client_len = sizeof(sa_cli);
sd = accept (listen_sd, (struct sockaddr*) &sa_cli, &client_len);
CHK_ERR(sd, "accept");
close (listen_sd);
printf ("Connection from %lx, port %x\n",
sa_cli.sin_addr.s_addr, sa_cli.sin_port);
/* ----------------------------------------------- */
/* TCP connection is ready. Do server side SSL. */
ssl = SSL_new (ctx); CHK_NULL(ssl);
SSL_set_fd (ssl, sd);
err = SSL_accept (ssl); CHK_SSL(err);
/* Get the cipher - opt */
printf ("SSL connection using %s\n", SSL_get_cipher (ssl));
/* Get client's certificate (note: beware of dynamic allocation) - opt */
client_cert = SSL_get_peer_certificate (ssl);
if (client_cert != NULL) {
printf ("Client certificate:\n");
str = X509_NAME_oneline (X509_get_subject_name (client_cert), 0, 0);
CHK_NULL(str);
printf ("\t subject: %s\n", str);
OPENSSL_free (str);
str = X509_NAME_oneline (X509_get_issuer_name (client_cert), 0, 0);
CHK_NULL(str);
printf ("\t issuer: %s\n", str);
OPENSSL_free (str);
/* We could do all sorts of certificate verification stuff here before
deallocating the certificate. */
X509_free (client_cert);
} else
printf ("Client does not have certificate.\n");
/* DATA EXCHANGE - Receive message and send reply. */
err = SSL_read (ssl, buf, sizeof(buf) - 1); CHK_SSL(err);
buf[err] = '\0';
printf ("Got %d chars:'%s'\n", err, buf);
err = SSL_write (ssl, "I hear you.", strlen("I hear you.")); CHK_SSL(err);
/* Clean up. */
close (sd);
SSL_free (ssl);
SSL_CTX_free (ctx);
return 0;
}
/* EOF - serv.cpp */
@rickyzhang-cn
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Author

1.证书的生成
生成server.csr和client.csr
openssl genrsa -des3 -out server.key 1024
openssl req -new -key server.key -out server.csr
openssl genrsa -des3 -out client.key 1024
openssl req -new -key client.key -out client.csr
生成ca.crt
openssl genrsa -des3 -out ca.key 1024
openssl req -new -x509 -key ca.key -out ca.crt
通过ca.crt颁发server.crt和client.crt
openssl ca -in server.csr -out server.crt -cert ca.crt -keyfile ca.key
openssl ca -in client.csr -out client.crt -cert ca.crt -keyfile ca.key
注：
这两条执行的时候可能因为没有指定openssl.cnf 会报错
不过没关系，我们用默认的 /etc/pki/tls/openssl.cnf 就可以
不过用默认的时候需要先执行下面两行：
touch /etc/pki/CA/index.txt
echo 00 > /etc/pki/CA/serial
2.证书的作用
证书主要用于在安全通信开始之前的认证
这个程序中client和server均需要通过证书认证彼此，这些过程主要通过OpenSSL库的API完成
client和server如果需要对对方进行认证，需要有ca.crt这个文件，因为client.crt和server.crt都是通过ca.crt签发的，ca.crt用来确认crt文件的合法性
认证完成后，client和server之间会协商一个对阵加密算法，对阵加密相关信息通过非对称加密传输，之后的数据通信是对称加密的，SSL connection using AES256-GCM-SHA384
3.SSL安全通信流程
OpenSSL初始化过程，设置证书文件和私钥文件，设置认证方式，生成SSL上下文ctx
通过Socket API获得用于网络通信的fd，通过ctx生成ssl，绑定ssl与fd
通过SSL_read()和SSL_Write()读写ssl进行安全通信

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