#1 Issues with files

// original from sf under GNU LESSER GENERAL PUBLIC LICENSE
// http://sourceforge.net/projects/rc4dotnet
// simplified by me ;) and fixed for files
using System;
using System.IO;
using System.Text;

namespace Encryption.LESR_RC4_Geffe
{
public interface ICoder
{
void Encrypt(string password, string file, string targetFile);
void Decrypt(string password, string file, string targetFile);
}
public class RC4: ICoder
{
private const int EncodingCode = 1251;

public void Encrypt(string password, string file, string targetFile)
{
byte[] content = encrypt(password, File.ReadAllBytes(file));
File.WriteAllBytes(targetFile, content);
}

public void Decrypt(string password, string file, string targetFile)
{
byte[] content = encrypt(password, File.ReadAllBytes(file));
File.WriteAllBytes(targetFile, content);
}

private int getAsciiCode(char character)
{
return (int)(Encoding.GetEncoding(EncodingCode).GetBytes(character + "")[0]);
}

private char fromAsciiCode(int asciiCode)
{
byte[] bytes = new byte[1];
bytes[0] = (byte)asciiCode;
return Encoding.GetEncoding(EncodingCode).GetString(bytes)[0];
}

private string hexToBinary(string packtype, string datastring)
{
int i, j, datalength, packsize;
byte[] bytes;
char[] hex;
string tmp;

datalength = datastring.Length;
packsize = (datalength/2) + (datalength % 2);
bytes = new byte[packsize];
hex = new char[2];

for (i = j = 0; i < datalength; i+=2)
{
hex[0] = datastring[i];
if (datalength - i == 1)
hex[1] = '0';
else
hex[1] = datastring[i + 1];
tmp = new string(hex, 0, 2);
try { bytes[j++] = byte.Parse(tmp, System.Globalization.NumberStyles.HexNumber); }
catch {} /* grin */
}
return Encoding.GetEncoding(EncodingCode).GetString(bytes);
}

public string binaryToHex(string bindata)
{
int i;
byte[] bytes = Encoding.GetEncoding(EncodingCode).GetBytes(bindata);
string hexString = "";
for (i = 0; i < bytes.Length; i++)
{
hexString += bytes[i].ToString("x2");
}
return hexString;
}

private byte[] encrypt(string password, byte[] data)
{
int a, i, j, k, tmp, pwd_length, data_length;
int[] key, box;
byte[] cipheredText;

password = hexToBinary("H*", password); // valid input, please!
pwd_length = password.Length;
data_length = data.Length;
key = new int[256];
box = new int[256];
cipheredText = new byte[data.Length];

for (i = 0; i < 256; i++)
{
key[i] = getAsciiCode(password[i % pwd_length]);
box[i] = i;
}
for (j = i = 0; i < 256; i++)
{
j = (j + box[i] + key[i]) % 256;
tmp = box[i];
box[i] = box[j];
box[j] = tmp;
}
for (a = j = i = 0; i < data_length; i++)
{
a = (a + 1) % 256;
j = (j + box[a]) % 256;
tmp = box[a];
box[a] = box[j];
box[j] = tmp;
k = box[((box[a] + box[j]) % 256)];
cipheredText[i] = (byte)(data[i] ^ k);
}
return cipheredText;
}
}
}