加密不定长数据 且 加密前数据和加密后数据大小相等,

1. 我使用的是OpenSSL库, AES算法
2. 想实现的功能是加密不定长的数据, 而且加密后的数据和原始数据一样大
求个能实现的算法, 求简单的, 本人基本上学过过算法

3. 比如加密下面这20个字节数据, 数据就被加密成32个字节的数据, 数据变大了
BYTE byIn[20 = {
'\x11' ,'\x22' ,'\x33' ,'\x44' ,'\x55' ,'\x66' ,'\x77' ,'\x88' ,
'\x99' ,'\xAA' ,'\x00' ,'\xCC' ,'\xDD' ,'\xEE' ,'\xFF' ,'\x00' ,
'\x45' ,'\x4A' ,'\x05' ,'\x8C' //加密之后变成了16个字节的加密数据
};


4. 下面是代码, 解密之后最后一块数据<20个字节的后4个字节不对了>, 因为AES是按照16个字节加密解密的
#include "stdafx.h"
#include <openssl/ssl.h>
#include <openssl/aes.h>
#include <openssl/rsa.h>
#include <openssl/rc4.h>

#include <string>
#include <iostream>
#include <fstream>
#include <PeClass.h>
using std::string;

//AES加密是以每组16个字节加密的
//AES加密(加密后数据, 加密前数据, 大小, 密钥)
void AesEncryption(OUT BYTE* bOutData, IN BYTE* bInData, IN DWORD dwSizeOut, OUT string strKey)
{
DWORD dwSize = Align(dwSizeOut, 16);

//new一片0x16对齐后的空间
BYTE* byNewIn = new BYTE[dwSize]();
memcpy(byNewIn, bInData, dwSizeOut);

//计算加密的次数
DWORD dwAlignNum = dwSizeOut / 16;

//最后一块剩余字节数
DWORD dwRemain = dwSizeOut % 16 ;

if (dwRemain)
{
++dwAlignNum;;
}

unsigned char aes_keybuf[32] = { 0 };
//memset(aes_keybuf,0,sizeof(aes_keybuf));
//将密钥复制到aes_keybuf
strcpy((char *)aes_keybuf, strKey.c_str());
//把明文密钥加密处理
AES_KEY aeskey;
AES_set_encrypt_key(aes_keybuf, 256, &aeskey);


//new一片0x16对齐后的空间
BYTE* byNewOut = new BYTE[dwSize]();


for (DWORD i = 0; i < dwAlignNum; i++)
{
AES_encrypt((const unsigned char *) ((DWORD)byNewIn + i * 16),
(unsigned char *) ((DWORD)byNewOut + i * 16),
&aeskey);
}


//把实际加密后数据, 复制到输出缓冲区
memcpy(bOutData, byNewOut, dwSizeOut);


delete byNewOut;
delete byNewIn;
}


//AES解密(解密后数据, 解密前数据, 大小, 密钥)
void AesDecryption(OUT BYTE* bOutData, IN BYTE* bInData, IN DWORD dwSizeOut, OUT string strKey)
{
DWORD dwSize = Align(dwSizeOut, 16);

//new一片0x16对齐后的空间
BYTE* byNewIn = new BYTE[dwSize]();
memcpy(byNewIn, bInData, dwSizeOut);

//计算加密的次数
DWORD dwAlignNum = dwSizeOut / 16;

//最后一块剩余字节数
DWORD dwRemain = dwSizeOut % 16;

if (dwRemain)
{
++dwAlignNum;;
}

unsigned char aes_keybuf[32] = { 0 };
//memset(aes_keybuf,0,sizeof(aes_keybuf));
//将密钥复制到aes_keybuf
strcpy((char *)aes_keybuf, strKey.c_str());
//把明文密钥加密处理
AES_KEY aeskey;
AES_set_decrypt_key(aes_keybuf, 256, &aeskey);


//new一片0x16对齐后的空间
BYTE* byNewOut = new BYTE[dwSize]();


for (DWORD i = 0; i < dwAlignNum; i++)
{
AES_decrypt((const unsigned char *)((DWORD)byNewIn + i * 16),
(unsigned char *)((DWORD)byNewOut + i * 16),
&aeskey);
}


//把实际加密后数据, 复制到输出缓冲区
memcpy(bOutData, byNewOut, dwSizeOut);

delete byNewOut;
delete byNewIn;
}


BYTE byIn[20] = {
'\x11' ,'\x22' ,'\x33' ,'\x44' ,'\x55' ,'\x66' ,'\x77' ,'\x88' ,
'\x99' ,'\xAA' ,'\x00' ,'\xCC' ,'\xDD' ,'\xEE' ,'\xFF' ,'\x00' ,
'\x45' ,'\x4A' ,'\x05' ,'\x8C'
};

int main(void) {

//BYTE byIn[20] = {};
BYTE byOut[20] = {};
BYTE byBuf[20] = {};

AesEncryption(byOut, byIn, 20, "123456");

AesDecryption(byBuf, byOut, 20, "123456");

return 0;
}