Willem's...

Windows XP KeyFinder Listing

using System;
using System.Collections;
using Microsoft.Win32;

namespace MSKeyFinder
{
  public class KeyDecoder
  {
    public enum Key { XP, Office10, Office11 };
    public static byte[] GetRegistryDigitalProductId(Key key)
    {
      byte[] digitalProductId = null;
      RegistryKey registry = null;
      switch(key)
      {
        // Open the XP subkey readonly.
        case Key.XP:
          registry = 
            Registry.LocalMachine.
              OpenSubKey(
                @"SOFTWARE\Microsoft\Windows NT\CurrentVersion",
                  false);
          break;
        // Open the Office 10 subkey readonly.
        case Key.Office10:
          // TODO: Open the registry key.
          break;
        // Open the Office 11 subkey readonly.
        case Key.Office11:
          // TODO: Open the registry key.
          break;
      }
      if(registry != null)
      {
        // TODO: For other products, key name maybe different.
        digitalProductId = registry.GetValue("DigitalProductId")
          as byte[];
        registry.Close();
      }
      return digitalProductId;
    }
    public static string DecodeProductKey(byte[] digitalProductId)
    {
      // Offset of first byte of encoded product key in 
      //  'DigitalProductIdxxx" REG_BINARY value. Offset = 34H.
      const int keyStartIndex = 52;
      // Offset of last byte of encoded product key in 
      //  'DigitalProductIdxxx" REG_BINARY value. Offset = 43H.
      const int keyEndIndex = keyStartIndex + 15;
      // Possible alpha-numeric characters in product key.
      char[] digits = new char[]
      {
        'B', 'C', 'D', 'F', 'G', 'H', 'J', 'K', 'M', 'P', 'Q', 'R', 
        'T', 'V', 'W', 'X', 'Y', '2', '3', '4', '6', '7', '8', '9',
      };
      // Length of decoded product key
      const int decodeLength = 29;
      // Length of decoded product key in byte-form.
      // Each byte represents 2 chars.
      const int decodeStringLength = 15;
      // Array of containing the decoded product key.
      char[] decodedChars = new char[decodeLength];
      // Extract byte 52 to 67 inclusive.
      ArrayList hexPid = new ArrayList();
      for (int i = keyStartIndex; i <= keyEndIndex; i++)
      {
        hexPid.Add(digitalProductId[i]);
      }
      for (int i = decodeLength - 1; i >= 0; i--)
      {
        // Every sixth char is a separator.
        if ((i + 1) % 6 == 0)
        {
          decodedChars[i] = '-';
        }
        else
        {
          // Do the actual decoding.
          int digitMapIndex = 0;
          for (int j = decodeStringLength - 1; j >= 0; j--)
          {
            int byteValue = (digitMapIndex << 8) | (byte)hexPid[j];
            hexPid[j] = (byte)(byteValue / 24);
            digitMapIndex = byteValue % 24;
            decodedChars[i] = digits[digitMapIndex];
          }
        }
      }
      return new string(decodedChars);
    }
  }
}