Decrypt xma/fsb.e.2 files from Power Gig

PowerGigDecryptor.cs

using System;
using System.IO;
using GameArchives.Seven45;

namespace PowerGigDecryptor
{
  class Program
  {
    static void Main(string[] args)
    {
      var directory = args[0];
      foreach (var f in Directory.EnumerateFiles(directory, "*.e.2", SearchOption.AllDirectories))
      {
        if (f.Contains(".xma"))
          DecryptXMA(f);
        else if (f.Contains(".fsb"))
          DecryptFSB(f);
        else
          continue;
      }
    }

    static void DecryptXMA(string file)
    {
      var outfile = file.EndsWith(".e.2") ? file.Substring(0, file.Length - 4) : (file + ".dec");
      var IV = new byte[16];
      using (var i = File.OpenRead(file))
      using (var o = File.OpenWrite(outfile))
      {
        using (var d = new PowerChordCryptStream(i, iv: IV))
        {
          d.Position = 0x400;
          d.Read(IV, 0, 16);
        }
        IV = Array.ConvertAll(IV, x => (byte)(~x));
        using (var d = new PowerChordCryptStream(i, iv: IV))
        {
          d.CopyTo(o);
        }
      }
    }

    static byte[] header = {
      0x46, 0x53, 0x42, 0x34,
      0x01, 0x00, 0x00, 0x00,
      0x50, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00
    };

    static void DecryptFSB(string file)
    {
      var outfile = file.EndsWith(".e.2") ? file.Substring(0, file.Length - 4) : (file + ".dec");
      var IV = new byte[16];
      using (var i = File.OpenRead(file))
      using (var o = File.OpenWrite(outfile))
      {

        using (var d = new PowerChordCryptStream(i, iv: IV))
        {
          d.Position = 0;
          d.Read(IV, 0, 16);
          var length = d.Length - 0x80;
          header[12] = (byte)(length & 0xFF);
          header[13] = (byte)(length >> 8 & 0xFF);
          header[14] = (byte)(length >> 16 & 0xFF);
          header[15] = (byte)(length >> 24 & 0xFF);
          for (var x = 0; x < header.Length; x++)
          {
            IV[x] ^= header[x];
          }
        }
        using (var d = new PowerChordCryptStream(i, iv: IV))
        {
          d.CopyTo(o);
        }
      }
    }
  }
}