OpenSSL库的RSA使用(下)-rsa函数方式

本文上接：OpenSSL库的RSA使用(上)-EVP方式，URL：http://blog.csdn.net/fenghaibo00/article/details/17248381

3      RSA函数方式

3.1 步骤

i.             生成RSA的key，包括三部分：公钥指数、私钥指数和模数（这些需要先了解一下RSA算法的原理）

ii.             将这三个数存下来，其中私钥指数和模数比较大，都是大素数

iii.             构造RSA结构，可以构造公钥和私钥RSA结构

iv.             利用构造的RSA结构的指针进行<公钥加密-私钥解密>或者<私钥加密-公钥解密>（注意加解密用到的密钥类型，不能用同一密钥进行加密和解密）

3.2  代码

3.2.1 头文件代码

#ifndef __OPENSSL_RSA_CODEC_H__    // rsa_op.h#define __OPENSSL_RSA_CODEC_H__// 公钥指数const unsigned char PUBLIC_EXPONENT_HEX[] = {0x01, 0x00, 0x01};// 私钥指数const unsigned char PRIVATE_EXPONENT_HEX[] = {0x68, 0x4D, 0x32, 0xAA, 0xE1, 0x3B, 0x28, 0xEA, 0x96, 0x48, 0x9A, 0x52, 0xCF, 0xD4, 0x11, \0xBE, 0x8E, 0xC1, 0xC2, 0x36, 0xF2, 0x95, 0xB3, 0x66, 0x2E, 0x54, 0x49, 0xFD, 0xAE, 0xDC, \0x1D, 0x8E, 0x86, 0xAA, 0xAD, 0x60, 0x5E, 0x82, 0xCD, 0x99, 0xA9, 0x96, 0x64, 0xB0, 0x70, \0xA0, 0xC5, 0x3A, 0x78, 0x8B, 0x5F, 0x85, 0x7A, 0x31, 0x21, 0x95, 0xDD, 0xDC, 0x99, 0x0E, \0x88, 0x4E, 0xA1, 0x3D, 0x8B, 0xF8, 0x58, 0xA1, 0x7C, 0xE8, 0x8C, 0x37, 0xE1, 0x1D, 0x59, \0x76, 0x81, 0x48, 0xFC, 0xF0, 0x1C, 0x37, 0x5A, 0x39, 0x23, 0x05, 0xAB, 0xC1, 0x75, 0xC8, \0x7F, 0x7A, 0xA6, 0xB9, 0x25, 0x9D, 0x36, 0xE7, 0x9E, 0xC5, 0xCE, 0x32, 0x45, 0x34, 0xE2, \0xEC, 0xDF, 0xB1, 0xD1, 0x4D, 0xC9, 0x31, 0x55, 0xBA, 0x14, 0xB1, 0xD1, 0x09, 0x22, 0x69, \0xCF, 0x09, 0xB9, 0xF6, 0xB6, 0x68, 0xA1, 0x49};// 模数const unsigned char MODULES_HEX[] = {0xD7, 0x42, 0xCC, 0x97, 0x4D, 0x35, 0x1A, 0x8F, 0xB3, 0xAA, 0x42, 0xAA, 0x6D, 0x10, 0xEB, \0x09, 0x58, 0xFA, 0xD2, 0xFB, 0x21, 0x0C, 0xDB, 0xBA, 0xB7, 0x22, 0x45, 0xE0, 0xF8, 0x1F, \0x40, 0x26, 0xFD, 0x00, 0xAF, 0x83, 0x1B, 0x5C, 0xE5, 0x68, 0x7B, 0x3F, 0x81, 0x21, 0x9E, \0xB4, 0x6B, 0x91, 0xCB, 0x5F, 0x2F, 0x6F, 0x18, 0xA6, 0x4B, 0xA0, 0x83, 0x33, 0x41, 0x7A, \0x75, 0xE3, 0x4B, 0xF1, 0x23, 0xCC, 0xA5, 0x76, 0xD0, 0x58, 0x8F, 0x87, 0xE6, 0x4C, 0x66, \0xB7, 0x83, 0x29, 0x16, 0xAE, 0x95, 0xE3, 0x76, 0x40, 0x0D, 0x54, 0xB8, 0x87, 0x0E, 0x8D, \0x66, 0x0E, 0x0E, 0x1D, 0xC4, 0x16, 0xFD, 0x4F, 0xFA, 0xC4, 0xB9, 0x89, 0x5D, 0x01, 0x2D, \0x86, 0x25, 0x44, 0x4B, 0x61, 0x31, 0xE2, 0xBD, 0x9A, 0xCD, 0x58, 0xE6, 0x6A, 0x94, 0xEC, \0x94, 0x77, 0x64, 0x50, 0x8C, 0x04, 0xE8, 0x3F};#define RSA_KEY_LENGTH 1024static const char rnd_seed[] = "string to make the random number generator initialized";class rsa_op{public:rsa_op();~rsa_op();// generate keys, usually no need to call it.int generate_key_str();// init paramsint set_params(const unsigned char *pub_expd = PUBLIC_EXPONENT_HEX, int pub_expd_len = 3, const unsigned char *pri_expd = PRIVATE_EXPONENT_HEX, int pri_expd_len = 128,const unsigned char *module = MODULES_HEX, int module_len = 128);// open keysint open_prikey_pubkey();int open_prikey();int open_pubkey();// private key to encryption and public key to decryptionint prikey_encrypt(const unsigned char *in, int in_len,unsigned char **out, int &out_len);int pubkey_decrypt(const unsigned char *in, int in_len,unsigned char **out, int &out_len);// public key to encryption and private key to decryptionint pubkey_encrypt(const unsigned char *in, int in_len,unsigned char **out, int &out_len);int prikey_decrypt(const unsigned char *in, int in_len,unsigned char **out, int &out_len);int close_key();protected:void free_res();private:RSA *_pub_key;RSA *_pri_key;unsigned char *_pub_expd;unsigned char *_pri_expd;unsigned char *_module;int _pub_expd_len;int _pri_expd_len;int _module_len;};#endif

3.2.2 实现文件代码

#include <stdio.h>   // rsa_op.cpp#include <string.h>#include <openssl/evp.h>#include <crypto/evp/evp_locl.h>#include <openssl/rand.h>#include <openssl/rsa.h>#include <openssl/pem.h>#include <openssl/err.h>#include "rsa_op.h"rsa_op::rsa_op(){_pub_key = NULL;_pri_key = NULL;_pub_expd = NULL;_pri_expd = NULL;_module = NULL;_pub_expd_len = 0;_pri_expd_len = 0;_module_len = 0;}rsa_op::~rsa_op(){close_key();free_res();}// 生成密钥函数int rsa_op::generate_key_str(){RSA *r = NULL;  int bits = RSA_KEY_LENGTH; unsigned long e = RSA_F4;r = RSA_generate_key(bits, e, NULL, NULL);  // 用作显示RSA_print_fp(stdout, r, 11);FILE *fp = fopen("f:\\new_keys", "w");if(NULL == fp){return -1;}RSA_print_fp(fp, r, 0);fclose(fp);return 0;}// 初始化参数int rsa_op::set_params(const unsigned char *pub_expd, int pub_expd_len,    const unsigned char *pri_expd, int pri_expd_len,   const unsigned char *module,   int module_len){if(pub_expd){_pub_expd_len = pub_expd_len;_pub_expd = new unsigned char[pub_expd_len];if(!_pub_expd){free_res();return -1;}memcpy(_pub_expd, pub_expd, _pub_expd_len);}if(pri_expd){_pri_expd_len = pri_expd_len;_pri_expd = new unsigned char[pri_expd_len];if(!_pri_expd){free_res();return -1;}memcpy(_pri_expd, pri_expd, pri_expd_len);}if(module){_module_len = module_len;_module = new unsigned char[module_len];if(!_module){free_res();return -1;}memcpy(_module, module, module_len);}return 0;}// 在一个key中同时打开公钥和私钥，该key既可用作公钥函数，也可用作私钥函数int rsa_op::open_prikey_pubkey(){//构建RSA数据结构_pri_key = RSA_new();_pri_key->e = BN_bin2bn(_pub_expd, _pub_expd_len, _pri_key->e);_pri_key->d = BN_bin2bn(_pri_expd, _pri_expd_len, _pri_key->d);_pri_key->n = BN_bin2bn(_module, _module_len, _pri_key->n);RSA_print_fp(stdout, _pri_key, 0);return 0;}// 打开私钥int rsa_op::open_prikey(){//构建RSA数据结构_pri_key = RSA_new();//_pri_key->e = BN_bin2bn(_pub_expd, _pub_expd_len, _pri_key->e);_pri_key->d = BN_bin2bn(_pri_expd, _pri_expd_len, _pri_key->d);_pri_key->n = BN_bin2bn(_module, _module_len, _pri_key->n);return 0;}// 打开公钥int rsa_op::open_pubkey(){//构建RSA数据结构_pub_key = RSA_new();_pub_key->e = BN_bin2bn(_pub_expd, _pub_expd_len, _pub_key->e);//_pub_key->d = BN_bin2bn(_pri_expd, _pri_expd_len, _pub_key->d);_pub_key->n = BN_bin2bn(_module, _module_len, _pub_key->n);RSA_print_fp(stdout, _pub_key, 0);return 0;}// 私钥加密函数int rsa_op::prikey_encrypt(const unsigned char *in, int in_len,   unsigned char **out, int &out_len){out_len =  RSA_size(_pri_key);*out =  (unsigned char *)malloc(out_len);if(NULL == *out){printf("prikey_encrypt:malloc error!\n");return -1;}memset((void *)*out, 0, out_len);printf("prikey_encrypt:Begin RSA_private_encrypt ...\n");int ret =  RSA_private_encrypt(in_len, in, *out, _pri_key, RSA_PKCS1_PADDING);//RSA_public_decrypt(flen, encData, decData, r,  RSA_NO_PADDING);return ret;}// 公钥解密函数，返回解密后的数据长度int rsa_op::pubkey_decrypt(const unsigned char *in, int in_len,   unsigned char **out, int &out_len){out_len =  RSA_size(_pub_key);*out =  (unsigned char *)malloc(out_len);if(NULL == *out){printf("pubkey_decrypt:malloc error!\n");return -1;}memset((void *)*out, 0, out_len);printf("pubkey_decrypt:Begin RSA_public_decrypt ...\n");int ret =  RSA_public_decrypt(in_len, in, *out, _pub_key, RSA_PKCS1_PADDING);return ret;}// 公钥加密函数int rsa_op::pubkey_encrypt(const unsigned char *in, int in_len,       unsigned char **out, int &out_len){out_len =  RSA_size(_pub_key);*out =  (unsigned char *)malloc(out_len);if(NULL == *out){printf("pubkey_encrypt:malloc error!\n");return -1;}memset((void *)*out, 0, out_len);printf("pubkey_encrypt:Begin RSA_public_encrypt ...\n");int ret =  RSA_public_encrypt(in_len, in, *out, _pub_key, RSA_PKCS1_PADDING/*RSA_NO_PADDING*/);return ret;}// 私钥解密函数，返回解密后的长度int rsa_op::prikey_decrypt(const unsigned char *in, int in_len,   unsigned char **out, int &out_len){out_len =  RSA_size(_pri_key);*out =  (unsigned char *)malloc(out_len);if(NULL == *out){printf("prikey_decrypt:malloc error!\n");return -1;}memset((void *)*out, 0, out_len);printf("prikey_decrypt:Begin RSA_private_decrypt ...\n");int ret =  RSA_private_decrypt(in_len, in, *out, _pri_key, RSA_PKCS1_PADDING);return ret;}// 释放分配的内存资源void rsa_op::free_res(){if(_pub_expd){delete []_pub_expd;_pub_expd = NULL;}if(_pri_expd){delete []_pri_expd;_pri_expd = NULL;}if(_module){delete []_module;_module = NULL;}}// 释放公钥和私钥结构资源int rsa_op::close_key(){if(_pub_key){RSA_free(_pub_key);_pub_key = NULL;}if(_pri_key){RSA_free(_pri_key);_pri_key = NULL;}return 0;}

3.2.3 测试代码

#include <stdio.h>                   // main.cpp#include <openssl/evp.h>#include <crypto/evp/evp_locl.h>#include <openssl/rand.h>#include <openssl/rsa.h>#include <openssl/pem.h>#include "rsa_op.h"#ifdef WIN32#pragma comment(lib, "libeay32.lib")#pragma comment(lib, "ssleay32.lib")#endifint main(int argc, char **argv){char origin_text[] = "hello world!";// 由于采用RSA_PKCS1_PADDING方式，因此最大长度不要超过（即- 11）int origin_len = sizeof(origin_text);int enc_len = 0;int dec_len = 0;unsigned char *enc_data = NULL;unsigned char *dec_data = NULL;rsa_op ro;// 下面是重新生成key的代码，一般不需要// ro.generate_key_str();ro.set_params();ro.open_prikey_pubkey();ro.open_pubkey();// 下面两行是私钥加密，公钥解密ro.prikey_encrypt((const unsigned char *)origin_text, origin_len, (unsigned char **)&enc_data, enc_len);ro.pubkey_decrypt(enc_data, enc_len, (unsigned char **)&dec_data, dec_len);// 下面两行是公钥加密，私钥解密//ro.pubkey_encrypt((const unsigned char *)origin_text, origin_len, (unsigned char **)&enc_data, enc_len);//ro.prikey_decrypt(enc_data, enc_len, (unsigned char **)&dec_data, dec_len);delete []enc_data;delete []dec_data;return 0;}

3.2.4 生成新密钥

在网上的Demo程序中，基本上都是固定的私钥指数和模数，没有写如何生成新的私钥指数和模数。在实际的使用中，不可能使用别人的私钥指数和模数，否则加密就成了空摆设。在该源代码中，使用rsa_op类generate_key_str函数可生成新的密钥参数，可打印到文件中，也可打印到标准输出stdout中。如下图：

将图中modules的值替换到MODULES_HEX变量的定义，privateExponent的值替换到PRIVATE_EXPONENT_HEX的定义，公钥指数不需要替换。

注意：有时候RSA_print_fp会在一个值前多打印一个00，在替换的时候不要这个00。

3.2.5 注意事项

Win32下注意添加链接时的lib文件，运行时需要相应的dll文件，需添加的lib文件：“libeay32.lib”和“ssleay32.lib”，运行需使用的dll文件：“libeay32.dll”和“ssleay32.dll”。

4. 问题整理

1.      RSA_print_fp在VS2005下导致程序退出

原因：在VS2005中，如果链接的运行库是MDD库（Multi-threaded Debug DLL），该问题就会出现，VS2005默认Debug版本链接MDD库。

解决方法：将程序属性设置中链接运行库改为MD（Multi-threaded DLL），如下图：

2.      使用RSA_NO_PADDING方式公钥加密时，源数据的第一个字节值不能大于等于0xC9,第二个字节值不能大于等于0x90，否则会失败。具体原因未找到，以下是测试的源数据：

unsigned char test[] = {0xD2, 0x90, 0x02};

在RSA的man页上也有说明，新的程序不应该使用RSA_NO_PADDING方式加密。

解决方法：使用RSA_PKCS1_PADDING方式加密解密。