对加密有所了解的读者，相信对这三种加密算法也已经有了些许了解。
比如RSA是一种很慢的加密方式，他是非对称的，需要有公钥和私钥。对文件中的数据，不大适合用这种方式来加密。因为我使用的是对整个图片文件的每16个字节进行加密，要是每次都对取出来的16字节进行RSA加密，那速度，是相当慢的。
所以，提供一种思路，既可以达到安全，，又可以做到加密。
比如我可以先把整个图片文件的每16个字节进行AES或者RC4加密，因为这两个加密函数是对称的，所以需要保存一个密钥，既可以解出来数据。对于这个密钥，我们只需要对他进行RSA加密，这样的安全性，就已经相当好了，速度也上得去了(这也是一般的思维方式)。
下面是所用到的对图片文件每16个字节进行AES、RC4加密的测试函数。附带一个简单的RSA加密测试，但是没区分公钥和私钥，对字符串进行RSA加密的这类资料网上太多了。
// ConsoleApplication1.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include <openssl/ssl.h>#include <openssl/aes.h>#include <openssl/rsa.h>#include <openssl/rc4.h>#pragma comment(lib,"libeay32.lib")#pragma comment(lib,"ssleay32.lib")#include "iostream"using namespace std;#include "string"#include "fstream"#define RELESE(P) if (P)\{\delete P;\P = NULL;\}#define RELESE_ARRAY(P) if (P) \{\delete[] P;\P = NULL;\}// 测试使用aes加密算法的例子void TestAesEncrypt(){unsigned char buf[16];memset(buf,1,sizeof(buf));strcpy((char *)buf, "zengraoli");cout << "current buf value is :" << buf << endl;unsigned char buf2[16];unsigned char buf3[16];unsigned char aes_keybuf[32];memset(aes_keybuf,0,sizeof(aes_keybuf));strcpy((char *)aes_keybuf, "zeng");cout << "current aes_keybuf value is :" << aes_keybuf << endl;AES_KEY aeskey;AES_set_encrypt_key(aes_keybuf,256,&aeskey);AES_encrypt(buf,buf2,&aeskey);cout << "current buf2 value is :" << buf2 << endl;memset(aes_keybuf,0,sizeof(aes_keybuf));strcpy((char *)aes_keybuf, "zeng2");cout << "current aes_keybuf value is :" << aes_keybuf << endl;AES_set_decrypt_key(aes_keybuf,256,&aeskey);AES_decrypt(buf2,buf3,&aeskey);cout << "current buf3 value is :" << buf3 << endl;if(memcmp(buf,buf3,sizeof(buf))==0)printf("test success\r\n");elseprintf("test fail\r\n");}// 测试使用aes加密文件算法的例子int TestAesEncryptFile(std::string in_file_path, std::string out_file_path,const char *rc4_encrypt_key, int encrypt_chunk_size = 16){ifstream fin(in_file_path.c_str(), ios::binary);ofstream fout(out_file_path, ios::binary);if(!fin){cout << "Can not open fin file." << endl;return 1;}if(!fout){cout << "Can not open fout file." << endl;return 1;}//用指定密钥对一段内存进行加密，结果放在outbuffer中unsigned char aes_keybuf[32];memset(aes_keybuf,0,sizeof(aes_keybuf));strcpy((char *)aes_keybuf, "zengraoli");AES_KEY aeskey;AES_set_encrypt_key(aes_keybuf, 256, &aeskey);char *in_data = new char[encrypt_chunk_size + 1];char *out_data = new char[encrypt_chunk_size + 1];while(!fin.eof()){fin.read(in_data, encrypt_chunk_size);AES_encrypt((const unsigned char *)in_data, (unsigned char *)out_data, &aeskey);fout.write(out_data, fin.gcount());};fout.close();fin.close();RELESE_ARRAY(in_data);RELESE_ARRAY(out_data);return 0;}// 测试使用aes解密文件算法的例子int TestAesDecryptFile(std::string in_file_path, std::string out_file_path,const char *rc4_dencrypt_key, int encrypt_chunk_size = 16){ifstream fin(in_file_path.c_str(), ios::binary);ofstream fout(out_file_path, ios::binary);if(!fin){cout << "Can not open fin file." << endl;return 1;}if(!fout){cout << "Can not open fout file." << endl;return 1;}//用指定密钥对一段内存进行加密，结果放在outbuffer中unsigned char aes_keybuf[32];memset(aes_keybuf,0,sizeof(aes_keybuf));strcpy((char *)aes_keybuf, "zengraoli");AES_KEY aeskey;AES_set_decrypt_key(aes_keybuf, 256, &aeskey);char *in_data = new char[encrypt_chunk_size + 1];char *out_data = new char[encrypt_chunk_size + 1];while( ! fin.eof() ){fin.read(in_data, encrypt_chunk_size);AES_decrypt((unsigned char *)in_data, (unsigned char *)out_data, &aeskey);fout.write(out_data, fin.gcount());};fout.close();fin.close();RELESE_ARRAY(in_data);RELESE_ARRAY(out_data);return 0;}// 测试使用aes加密算法的例子void TestRsaEncrypt(){BIGNUM b={0};RSA* pRsa = RSA_generate_key(1024, RSA_F4, 0, 0);//pRsa中包含了N D,你这里自己修改就可以了char in_data[] = "zengraoli";cout << "current in_data value is : " << in_data << endl;int len = RSA_size(pRsa);char* out_data = new char[len];memset(out_data, 0, len);RSA_public_encrypt( sizeof(in_data), (unsigned char *)in_data,(unsigned char *)out_data, pRsa, RSA_PKCS1_PADDING);cout << "current out_data value is : " << out_data << endl;char out[1024] = {0};RSA_private_decrypt(len, (unsigned char *)out_data,(unsigned char *)out, pRsa, RSA_PKCS1_PADDING);RSA_free(pRsa);cout << "current out value is : " << out << endl;}// 测试使用rc4加密算法的例子void TestRc4Encrypt(){char code[64]={0};int codelen = sizeof(code);memcpy_s(code, 64, "This is secrect", 15);cout << "before encrypt :" << code << endl;unsigned char *outbuffer = new unsigned char[codelen];//用指定密钥对一段内存进行加密，结果放在outbuffer中RC4_KEY rc4_key;RC4_set_key(&rc4_key,7,(unsigned char *)"zenraoli");RC4(&rc4_key,codelen,(unsigned char *)code,outbuffer);cout << "after encrypt :" << outbuffer << endl;//用指定密钥对outbuffer中的密文进行解密，结果放回原来的内存memset(code,0,sizeof(code));RC4_set_key(&rc4_key,7,(unsigned char *)"zenraoli");//这里必须再次设置密钥RC4(&rc4_key,codelen,outbuffer,(unsigned char *)code);cout << "after decrypt :" << code << endl;if (outbuffer){delete[] outbuffer;outbuffer = NULL;}}// 测试使用rc4加密文件算法的例子int TestRc4EncryptFile(std::string in_file_path, std::string out_file_path,const char *rc4_encrypt_key, int encrypt_chunk_size = 16){ifstream fin(in_file_path.c_str(), ios::binary);ofstream fout(out_file_path, ios::binary);if(!fin){cout << "Can not open fin file." << endl;return 1;}if(!fout){cout << "Can not open fout file." << endl;return 1;}//用指定密钥对一段内存进行加密，结果放在outbuffer中char code[64] = {0};int codelen = sizeof(code);RC4_KEY rc4_key;RC4_set_key(&rc4_key, strlen(rc4_encrypt_key), (unsigned char *)rc4_encrypt_key);char *in_data = new char[encrypt_chunk_size + 1];char *out_data = new char[encrypt_chunk_size + 1];while(!fin.eof()){fin.read(in_data, encrypt_chunk_size);RC4(&rc4_key, (size_t)fin.gcount(),(unsigned char *)in_data, (unsigned char *)out_data);fout.write(out_data, fin.gcount());};fout.close();fin.close();RELESE_ARRAY(in_data);RELESE_ARRAY(out_data);return 0;}// 测试使用rc4解密文件算法的例子int TestRc4DecryptFile(std::string in_file_path, std::string out_file_path,const char *rc4_dencrypt_key, int encrypt_chunk_size = 16){ifstream fin(in_file_path.c_str(), ios::binary);ofstream fout(out_file_path, ios::binary);if(!fin){cout << "Can not open fin file." << endl;return 1;}if(!fout){cout << "Can not open fout file." << endl;return 1;}//用指定密钥对一段内存进行加密，结果放在outbuffer中char code[64] = {0};int codelen = sizeof(code);RC4_KEY rc4_key;RC4_set_key(&rc4_key, strlen(rc4_dencrypt_key), (unsigned char *)rc4_dencrypt_key);char *in_data = new char[encrypt_chunk_size + 1];char *out_data = new char[encrypt_chunk_size + 1];while(!fin.eof()){fin.read(in_data, encrypt_chunk_size);RC4(&rc4_key, (size_t)fin.gcount(),(unsigned char *)in_data, (unsigned char *)out_data);fout.write(out_data, fin.gcount());};fout.close();fin.close();RELESE_ARRAY(in_data);RELESE_ARRAY(out_data);return 0;}int _tmain(int argc, _TCHAR* argv[]){// TestAesEncrypt();// // TestAesEncryptFile("1.gif", "2.gif", "zengraoli");// // TestAesDecryptFile("2.gif", "3.gif", "zengraoli");TestRsaEncrypt();TestRc4Encrypt();TestRc4EncryptFile("1.gif", "2.gif", "zengraoli");TestRc4DecryptFile("2.gif", "3.gif", "zengraoli");return 0;}
整个测试工程的地址是：
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