如何對一個(gè)已有字符串加密 

CString ChangWhiteBlackKey(CString strText,bool bWhite)
{
	int				i ;
	char	tCh1,tCh2;
	CString			strReturn ;
	strReturn.Empty();
	if(bWhite)//明碼=>暗碼
	{
		for(i = 0 ; i < strText.GetLength(); i++)
		{
			unsigned short int t = strText.GetAt(i) + 11;
			if(t > 255)
			{
				tCh1 = 'A' + rand()%26;
				tCh2 = t - 256 +100/* +100避免出現(xiàn)0(結(jié)束符) */ ;
			}
			else
			{
				tCh1 = '0' + rand()%10;
				tCh2 = t ;
			}
			strReturn = (strReturn + tCh1) + tCh2 ;
		}
	}
	else
	{
		for(i = 0 ; i < strText.GetLength() ; i+=2)
		{
			tCh1 = strText[i];
			tCh2 = strText[i+1];
			unsigned short int t;
			if(tCh1 > 'A')
				t = 256 + (tCh2 - 100) - 11 ;
			else
				t = tCh2 - 11 ;
			strReturn += t ;
				
		}
	}
	return strReturn ;
}



簡單加密，呵呵，提供一個(gè)最簡單的
代碼僅供參考！
char strKey[] = {0x03,0x25, 0x45, 0x5F, 0xFA};//你的密鑰，長度隨你定了
CString szData("你的要加密的數(shù)據(jù)");
char *pData = szData.GetBuffer(0);
char *p = new char[szData.GetLength()];
int nKeyLen = sizeof(strKey);
for(int i=0; i<szData.GetLength(); i++)
{
  *pData = *pData ^ strKey[i%nKeyLen];//每字節(jié)與對應(yīng)的密鑰字節(jié)進(jìn)行異或運(yùn)算
  pData++;
}
試試吧，提供點(diǎn)思路