使用openssl中的加密函数AES、RC4、RSA对文件加密的一个例子

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");
	else
		printf("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：

http://download.csdn.net/detail/zengraoli/6636897