diff --git a/ArcFormats/ArcFormats.csproj b/ArcFormats/ArcFormats.csproj
index 50042c95..845b2104 100644
--- a/ArcFormats/ArcFormats.csproj
+++ b/ArcFormats/ArcFormats.csproj
@@ -286,6 +286,7 @@
+
diff --git a/ArcFormats/Stack/ArcGPK.cs b/ArcFormats/Stack/ArcGPK.cs
new file mode 100644
index 00000000..38a3490f
--- /dev/null
+++ b/ArcFormats/Stack/ArcGPK.cs
@@ -0,0 +1,141 @@
+//! \file ArcGPK.cs
+//! \date 2018 Nov 01
+//! \brief Stack script engine resource archive.
+//
+// Copyright (C) 2018 by morkt
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+//
+
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.Composition;
+using System.IO;
+using System.Linq;
+using System.Text;
+using GameRes.Compression;
+
+namespace GameRes.Formats.Stack
+{
+ internal class GpkEntry : PackedEntry
+ {
+ public byte[] Header;
+ }
+
+ [Export(typeof(ArchiveFormat))]
+ public class GpkOpener : ArchiveFormat
+ {
+ public override string Tag { get { return "GPK/STACK"; } }
+ public override string Description { get { return "Stack script engine resource archive"; } }
+ public override uint Signature { get { return 0; } }
+ public override bool IsHierarchic { get { return true; } }
+ public override bool CanWrite { get { return false; } }
+
+ public override ArcFile TryOpen (ArcView file)
+ {
+ long idx_offset = file.MaxOffset - 32;
+ if (idx_offset <= 0)
+ return null;
+ if (!file.View.AsciiEqual (idx_offset, "STKFile0PIDX") ||
+ !file.View.AsciiEqual (idx_offset+16, "STKFile0PACKFILE"))
+ return null;
+ uint idx_size = file.View.ReadUInt32 (idx_offset+12);
+ if (idx_size > idx_offset)
+ return null;
+ idx_offset -= idx_size;
+ var key = QueryKey (file.Name);
+ if (null == key)
+ return null;
+ Stream input = file.CreateStream (idx_offset, idx_size);
+ input = new ByteStringEncryptedStream (input, key);
+ input.Position = 4;
+ using (input = new ZLibStream (input, CompressionMode.Decompress))
+ using (var index = new BinaryStream (input, file.Name))
+ {
+ var name_buffer = new byte[0x100];
+ var dir = new List();
+ while (index.PeekByte() != -1)
+ {
+ int name_length = index.ReadUInt16() * 2;
+ if (0 == name_length)
+ break;
+ if (name_length > name_buffer.Length)
+ name_buffer = new byte[name_length];
+ index.Read (name_buffer, 0, name_length);
+ var name = Encoding.Unicode.GetString (name_buffer, 0, name_length);
+ var entry = Create (name);
+
+ index.ReadInt32();
+ index.ReadInt16();
+ entry.Offset = index.ReadUInt32();
+ entry.Size = index.ReadUInt32();
+ if (!entry.CheckPlacement (file.MaxOffset))
+ return null;
+ index.ReadInt32();
+ entry.UnpackedSize = index.ReadUInt32();
+ entry.IsPacked = entry.UnpackedSize != 0;
+ int header_length = index.ReadUInt8();
+ if (header_length > 0)
+ entry.Header = index.ReadBytes (header_length);
+ dir.Add (entry);
+ }
+ if (0 == dir.Count)
+ return null;
+ return new ArcFile (file, this, dir);
+ }
+ }
+
+ public override Stream OpenEntry (ArcFile arc, Entry entry)
+ {
+ var gent = (GpkEntry)entry;
+ Stream input = arc.File.CreateStream (entry.Offset, entry.Size);
+ if (gent.Header != null)
+ input = new PrefixStream (gent.Header, input);
+ if (gent.IsPacked)
+ input = new ZLibStream (input, CompressionMode.Decompress);
+ return input;
+ }
+
+ byte[] QueryKey (string arc_name)
+ {
+ if (VFS.IsVirtual)
+ return null;
+ var dir = VFS.GetDirectoryName (arc_name);
+ var parent_dir = Directory.GetParent (dir).FullName;
+ var exe_files = VFS.GetFiles (VFS.CombinePath (parent_dir, "*.exe")).Concat (VFS.GetFiles (VFS.CombinePath (dir, "*.exe")));
+ foreach (var exe_entry in exe_files)
+ {
+ try
+ {
+ using (var exe = new ExeFile.ResourceAccessor (exe_entry.Name))
+ {
+ var code = exe.GetResource ("CIPHERCODE", "CODE");
+ if (null == code)
+ continue;
+ if (20 == code.Length)
+ code = new CowArray (code, 4, 16).ToArray();
+ return code;
+ }
+ }
+ catch { /* ignore errors */ }
+ }
+ return null;
+ }
+ }
+}