touhu game android global-metadata decrypt

gmetadata_decrypt.cs

using System;
using System.IO;
namespace Globalmeta{
	class Globalmetadec{
		public static void Main(string[] argv){
			using (FileStream fs=new FileStream(argv[0],FileMode.Open)) {
				using (BinaryReader bs=new BinaryReader(fs)) {
					byte[] pwd=new byte[]{0x75,0xCD,0xB2,0xCF,0x19,0xDB,0x08,0x3F};
					byte[] header=new byte[]{0xAF,0x1B,0xB1,0xFA,0x18,0x00,0x00,0x00,0x08,0x01,0x00,0x00};
					byte[] use_pwd=new byte[8];
					byte[] buffer=new byte[fs.Length];
					for (int i = 0; i < header.Length; i++) {
						buffer[i]=header[i];
					}
					fs.Position=header.Length;
					for (int i = header.Length; i < (fs.Length); i++) {
						buffer[i]=(byte)(bs.ReadByte()^pwd[(i-header.Length)%(pwd.Length)]);
					}
					File.WriteAllBytes(argv[0]+".dec",buffer);
				}
			}
		}
	}
}