GARbro-mirror/ArcFormats/AZSys/ArcEncrypted.cs

349 lines
14 KiB
C#

//! \file ArcEncrypted.cs
//! \date Thu Jan 14 03:27:52 2016
//! \brief Encrypted AZ system resource archives.
//
// Copyright (C) 2016 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 GameRes.Compression;
using GameRes.Utility;
using System;
using System.Collections.Generic;
using System.ComponentModel.Composition;
using System.IO;
using System.Linq;
namespace GameRes.Formats.AZSys
{
[Serializable]
public class EncryptionScheme
{
public readonly uint IndexKey;
public readonly uint? ContentKey;
public static readonly uint[] DefaultSeed = { 0x2F4D7DFE, 0x47345292, 0x1BA5FE82, 0x7BC04525 };
public EncryptionScheme (uint ikey, uint ckey)
{
IndexKey = ikey;
ContentKey = ckey;
}
public EncryptionScheme (uint[] iseed)
{
IndexKey = GenerateKey (iseed);
ContentKey = null;
}
public EncryptionScheme (uint[] iseed, byte[] cseed)
{
IndexKey = GenerateKey (iseed);
ContentKey = GenerateContentKey (cseed);
}
public static uint GenerateKey (uint[] seed)
{
if (null == seed)
throw new ArgumentNullException ("seed");
if (seed.Length < 4)
throw new ArgumentException();
byte[] seed_bytes = new byte[0x10];
Buffer.BlockCopy (seed, 0, seed_bytes, 0, 0x10);
uint key = Crc32.UpdateCrc (~seed[0], seed_bytes, 0, seed_bytes.Length)
^ Crc32.UpdateCrc (~(seed[1] & 0xFFFF), seed_bytes, 0, seed_bytes.Length)
^ Crc32.UpdateCrc (~(seed[1] >> 16), seed_bytes, 0, seed_bytes.Length)
^ Crc32.UpdateCrc (~seed[2], seed_bytes, 0, seed_bytes.Length)
^ Crc32.UpdateCrc (~seed[3], seed_bytes, 0, seed_bytes.Length);
return seed[0] ^ ~key;
}
public static uint GenerateContentKey (byte[] env_bytes)
{
if (null == env_bytes)
throw new ArgumentNullException ("env_bytes");
if (env_bytes.Length < 0x10)
throw new ArgumentException();
uint crc = Crc32.Compute (env_bytes, 0, 0x10);
var sfmt = new FastMersenneTwister (crc);
var seed = new uint[4];
seed[0] = sfmt.GetRand32();
seed[1] = sfmt.GetRand32() & 0xFFFF;
seed[1] |= sfmt.GetRand32() << 16;
seed[2] = sfmt.GetRand32();
seed[3] = sfmt.GetRand32();
return GenerateKey (seed);
}
}
[Serializable]
public class AzScheme : ResourceScheme
{
public Dictionary<string, EncryptionScheme> KnownSchemes;
}
internal class AzArchive : ArcFile
{
public readonly uint SysenvKey;
public readonly uint RegularKey;
public AzArchive (ArcView arc, ArchiveFormat impl, ICollection<Entry> dir, uint syskey, uint regkey)
: base (arc, impl, dir)
{
SysenvKey = syskey;
RegularKey = regkey;
}
}
[Export(typeof(ArchiveFormat))]
public class ArcEncryptedOpener : ArchiveFormat
{
public override string Tag { get { return "ARC/AZ/encrypted"; } }
public override string Description { get { return "AZ system encrypted resource archive"; } }
public override uint Signature { get { return 0; } }
public override bool IsHierarchic { get { return false; } }
public override bool CanCreate { get { return false; } }
public static Dictionary<string, EncryptionScheme> KnownSchemes = new Dictionary<string, EncryptionScheme>
{
{ "Default", new EncryptionScheme (EncryptionScheme.DefaultSeed) },
};
public override ResourceScheme Scheme
{
get { return new AzScheme { KnownSchemes = KnownSchemes }; }
set { KnownSchemes = ((AzScheme)value).KnownSchemes; }
}
public ArcEncryptedOpener ()
{
Extensions = new string[] { "arc" };
Signatures = new uint[] { 0x53EA06EB, 0x74F98F2F };
}
EncryptionScheme CurrentScheme;
public override ArcFile TryOpen (ArcView file)
{
byte[] header_encrypted = file.View.ReadBytes (0, 0x30);
if (header_encrypted.Length < 0x30)
return null;
byte[] header = new byte[header_encrypted.Length];
if (CurrentScheme != null)
{
try
{
Buffer.BlockCopy (header_encrypted, 0, header, 0, header.Length);
Decrypt (header, 0, CurrentScheme.IndexKey);
if (Binary.AsciiEqual (header, 0, "ARC\0"))
{
var arc = ReadIndex (file, header, CurrentScheme);
if (null != arc)
return arc;
}
}
catch { /* ignore parse errors */ }
}
foreach (var scheme in KnownSchemes.Values)
{
Buffer.BlockCopy (header_encrypted, 0, header, 0, header.Length);
Decrypt (header, 0, scheme.IndexKey);
if (Binary.AsciiEqual (header, 0, "ARC\0"))
{
var arc = ReadIndex (file, header, scheme);
if (null != arc)
CurrentScheme = new EncryptionScheme (arc.SysenvKey, arc.RegularKey);
return arc;
}
}
return null;
}
public override Stream OpenEntry (ArcFile arc, Entry entry)
{
var azarc = arc as AzArchive;
if (null == azarc)
return base.OpenEntry (arc, entry);
var data = arc.File.View.ReadBytes (entry.Offset, entry.Size);
if (entry.Name.Equals ("sysenv.tbl", StringComparison.InvariantCultureIgnoreCase))
{
Decrypt (data, entry.Offset, azarc.SysenvKey);
return UnpackData (data);
}
Decrypt (data, entry.Offset, azarc.RegularKey);
if (data.Length > 0x14 && Binary.AsciiEqual (data, 0, "ASB\0"))
{
return OpenAsb (data);
}
return new MemoryStream (data);
}
Stream OpenAsb (byte[] data)
{
int packed_size = LittleEndian.ToInt32 (data, 4);
if (packed_size <= 4 || packed_size > data.Length-0x10)
return new MemoryStream (data);
uint unpacked_size = LittleEndian.ToUInt32 (data, 8);
uint key = unpacked_size ^ 0x9E370001;
unsafe
{
fixed (byte* raw = &data[0x10])
{
uint* data32 = (uint*)raw;
for (int i = packed_size/4; i > 0; --i)
*data32++ -= key;
}
}
var asb = UnpackData (data, 0x10);
var header = new byte[0x10];
Buffer.BlockCopy (data, 0, header, 0, 0x10);
return new PrefixStream (header, asb);
}
byte[] ReadSysenvSeed (ArcView file, Entry entry, uint key)
{
var data = file.View.ReadBytes (entry.Offset, entry.Size);
if (data.Length <= 4)
throw new InvalidFormatException ("Invalid sysenv.tbl size");
Decrypt (data, entry.Offset, key);
uint adler32 = LittleEndian.ToUInt32 (data, 0);
if (adler32 != Adler32.Compute (data, 4, data.Length-4))
throw new InvalidEncryptionScheme();
using (var input = new MemoryStream (data, 4, data.Length-4))
using (var sysenv_stream = new ZLibStream (input, CompressionMode.Decompress))
{
var seed = new byte[0x10];
if (0x10 != sysenv_stream.Read (seed, 0, 0x10))
throw new InvalidFormatException ("Invalid sysenv.tbl size");
return seed;
}
}
Stream UnpackData (byte[] data, int index = 0)
{
int length = data.Length - index;
if (length <= 4)
return new MemoryStream (data, index, length);
uint adler32 = LittleEndian.ToUInt32 (data, index);
if (adler32 != Adler32.Compute (data, index+4, length-4))
return new MemoryStream (data, index, length);
var input = new MemoryStream (data, index+4, length-4);
return new ZLibStream (input, CompressionMode.Decompress);
}
AzArchive ReadIndex (ArcView file, byte[] header, EncryptionScheme scheme)
{
int ext_count = LittleEndian.ToInt32 (header, 4);
int count = LittleEndian.ToInt32 (header, 8);
uint index_length = LittleEndian.ToUInt32 (header, 12);
if (ext_count < 1 || ext_count > 8 || !IsSaneCount (count) || index_length >= file.MaxOffset)
return null;
var packed_index = file.View.ReadBytes (header.Length, index_length);
if (packed_index.Length != index_length)
return null;
Decrypt (packed_index, header.Length, scheme.IndexKey);
uint checksum = LittleEndian.ToUInt32 (packed_index, 0);
if (checksum != Adler32.Compute (packed_index, 4, packed_index.Length-4))
{
if (checksum != Crc32.Compute (packed_index, 4, packed_index.Length-4))
throw new InvalidFormatException ("Index checksum mismatch");
}
uint base_offset = (uint)header.Length + index_length;
using (var input = new MemoryStream (packed_index, 4, packed_index.Length-4))
using (var zstream = new ZLibStream (input, CompressionMode.Decompress))
using (var index = new BinaryReader (zstream))
{
var dir = new List<Entry> (count);
var name_buffer = new byte[0x20];
for (int i = 0; i < count; ++i)
{
uint offset = index.ReadUInt32();
uint size = index.ReadUInt32();
uint crc = index.ReadUInt32();
index.ReadInt32();
if (name_buffer.Length != index.Read (name_buffer, 0, name_buffer.Length))
return null;
var name = Binary.GetCString (name_buffer, 0, 0x20);
if (0 == name.Length)
return null;
var entry = FormatCatalog.Instance.Create<Entry> (name);
entry.Offset = base_offset + offset;
entry.Size = size;
if (!entry.CheckPlacement (file.MaxOffset))
return null;
dir.Add (entry);
}
uint content_key = GetContentKey (file, dir, scheme);
return new AzArchive (file, this, dir, scheme.IndexKey, content_key);
}
}
static void Decrypt (byte[] data, long offset, uint key)
{
ulong hash = key * 0x9E370001ul;
if (0 != (offset & 0x3F))
{
hash = Binary.RotL (hash, (int)offset);
}
for (uint i = 0; i < data.Length; ++i)
{
data[i] ^= (byte)hash;
hash = Binary.RotL (hash, 1);
}
}
uint GetContentKey (ArcView file, List<Entry> dir, EncryptionScheme scheme)
{
if (null != scheme.ContentKey)
return scheme.ContentKey.Value;
if ("system.arc".Equals (Path.GetFileName (file.Name), StringComparison.InvariantCultureIgnoreCase))
{
var sysenv = dir.FirstOrDefault (e => e.Name.Equals ("sysenv.tbl", StringComparison.InvariantCultureIgnoreCase));
if (null != sysenv)
{
var seed = ReadSysenvSeed (file, sysenv, scheme.IndexKey);
return EncryptionScheme.GenerateContentKey (seed);
}
}
else
{
var system_arc = VFS.CombinePath (Path.GetDirectoryName (file.Name), "system.arc");
using (var arc = VFS.OpenView (system_arc))
{
var header = arc.View.ReadBytes (0, 0x30);
Decrypt (header, 0, scheme.IndexKey);
using (var arc_file = ReadIndex (arc, header, scheme))
{
var sysenv = arc_file.Dir.FirstOrDefault (e => e.Name.Equals ("sysenv.tbl", StringComparison.InvariantCultureIgnoreCase));
if (null != sysenv)
{
var seed = ReadSysenvSeed (arc, sysenv, scheme.IndexKey);
return EncryptionScheme.GenerateContentKey (seed);
}
}
}
}
return scheme.IndexKey;
}
}
}