crypt.cpp

l2研究

#include <windows.h>
#include "Crypt.h"

CCrypt::CCrypt(void)
{
	_key=NULL;
}

CCrypt::~CCrypt(void)
{
}

void CCrypt::setKey(char key[], int keylength)
{
    _key = new char[keylength];
	memcpy(_key, key, keylength);
}

INT64 CCrypt::decrypt(char raw[], int rawlength)
{
    if(_key == NULL)
        return 0L;
    int temp = 0;
    int j = 0;
    for(int i = 0; i < rawlength; i++)
    {
        int temp2 = raw[i] & 0xff;
        raw[i] = (char)(temp2 ^ (_key[j++] & 0xff) ^ temp);
        temp = temp2;
        if(j > 7)
            j = 0;
    }

    INT64 old = _key[0] & 0xff;
    old |= _key[1] << 8 & 0xff00;
    old |= _key[2] << 16 & 0xff0000;
    old |= _key[3] << 24 & 0xff000000;
    old += rawlength;
    _key[0] = (char)(int)(old & 255L);
    _key[1] = (char)(int)(old >> 8 & 255L);
    _key[2] = (char)(int)(old >> 16 & 255L);
    _key[3] = (char)(int)(old >> 24 & 255L);
    return old;
}

INT64 CCrypt::encrypt(char raw[], int rawlength)
{
    if(_key == NULL)
        return 0L;
    int temp = 0;
    int j = 0;
    for(int i = 0; i < rawlength; i++)
    {
        int temp2 = raw[i] & 0xff;
        raw[i] = (char)(temp2 ^ (_key[j++] & 0xff) ^ temp);
        temp = raw[i];
        if(j > 7)
            j = 0;
    }

    INT64 old = _key[0] & 0xff;
    old |= _key[1] << 8 & 0xff00;
    old |= _key[2] << 16 & 0xff0000;
    old |= _key[3] << 24 & 0xff000000;
    old += rawlength;
    _key[0] = (char)(int)(old & 255L);
    _key[1] = (char)(int)(old >> 8 & 255L);
    _key[2] = (char)(int)(old >> 16 & 255L);
    _key[3] = (char)(int)(old >> 24 & 255L);
    return old;
}