help me with xor encryption in c#
- by x86shadow
I wrote this code in c# to encrypt a text with a key :
using System;
using System.Linq;
using System.Collections.Generic;
using System.Text;
namespace ENCRYPT
{
class XORENC
{
private static int Bin2Dec(string num)
{
int _num = 0;
for (int i = 0; i < num.Length; i++)
{
_num += (int)Math.Pow(2, num.Length - i - 1) * int.Parse(num[i].ToString());
}
return _num;
}
private static string Dec2Bin(int num)
{
if (num < 2) return num.ToString();
return Dec2Bin(num / 2) + (num % 2).ToString();
}
public static string StrXor(string str, string key)
{
string _str = "";
string _key = "";
string _dec = "";
string _temp = "";
for (int i = 0; i < str.Length; i++)
{
_temp = Dec2Bin(str[i]);
for (int j = 0; j < 8 - _temp.Length + 1; j++)
{
_temp = '0' + _temp;
}
_str += _temp;
}
for (int i = 0; i < key.Length; i++)
{
_temp = Dec2Bin(key[i]);
for (int j = 0; j < 8 - _temp.Length + 1; j++)
{
_temp = '0' + _temp;
}
_key += _temp;
}
while (_key.Length < _str.Length)
{
_key += _key;
}
if (_key.Length > _str.Length) _key = _key.Substring(0, _str.Length);
for (int i = 0; i < _str.Length; i++)
{
if (_str[i] == _key[i]) { _dec += '0'; } else { _dec += '1'; }
}
_str = "";
for (int i = 0; i < _dec.Length; i = i + 8)
{
char _chr = (char)0;
_chr = (char)Bin2Dec(_dec.Substring(i, 8));
_str += _chr;
}
return _str;
}
}
}
the problem is that I always get error when I want to decrypt an encryted text with this code. see the example below for more info :
string enc_text = ENCRYPT.XORENC("abc","a"); //enc_text = " ??"
string dec_text = ENCRYPT.XORENC(enc_text,"a"); //ERROR
any one can help ?
