GARbro-mirror/ArcFormats/Unity/ArcDSM.cs

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2022-05-01 03:39:44 +08:00
//! \file ArcDSM.cs
//! \date 2022 Apr 30
//! \brief Encrypted DSM script file as an archive.
//
// Copyright (C) 2022 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.Security.Cryptography;
using System.Text;
namespace GameRes.Formats.Unity
{
[Export(typeof(ArchiveFormat))]
public class DsmOpener : ArchiveFormat
{
public override string Tag { get { return "DSM/UNITY"; } }
public override string Description { get { return "Unity engine encrypted script file"; } }
public override uint Signature { get { return 0; } }
public override bool IsHierarchic { get { return false; } }
public override bool CanWrite { get { return false; } }
const string DefaultPassword = "pass";
public override ArcFile TryOpen (ArcView file)
{
if (!VFS.IsPathEqualsToFileName (file.Name, "data.dsm")
|| (file.View.ReadUInt32 (0) & 0xFFFFFF) != 0xBFBBEF) // UTF-8 BOM
return null;
var dir = new List<Entry> {
new Entry {
Name = "data.txt",
Type = "script",
Offset = 0,
Size = (uint)file.MaxOffset / 4 * 3,
}
};
return new ArcFile (file, this, dir);
}
public override Stream OpenEntry (ArcFile arc, Entry entry)
{
using (var input = arc.File.CreateStream())
using (var reader = new StreamReader (input))
{
var sourceString = reader.ReadToEnd();
var text = DecryptString (sourceString, DefaultPassword);
return new BinMemoryStream (text, entry.Name);
}
}
static byte[] DecryptString (string sourceString, string password)
{
var rijndaelManaged = new RijndaelManaged();
byte[] key, iv;
GenerateKeyFromPassword (password, rijndaelManaged.KeySize, out key, rijndaelManaged.BlockSize, out iv);
rijndaelManaged.Key = key;
rijndaelManaged.IV = iv;
var array = Convert.FromBase64String (sourceString);
using (var cryptoTransform = rijndaelManaged.CreateDecryptor())
{
return cryptoTransform.TransformFinalBlock (array, 0, array.Length);
}
}
static readonly byte[] DefaultSalt = Encoding.UTF8.GetBytes("saltは必ず8バイト以上");
static void GenerateKeyFromPassword (string password, int keySize, out byte[] key, int blockSize, out byte[] iv)
{
var rfc2898DeriveBytes = new Rfc2898DeriveBytes (password, DefaultSalt);
rfc2898DeriveBytes.IterationCount = 1000;
key = rfc2898DeriveBytes.GetBytes (keySize / 8);
iv = rfc2898DeriveBytes.GetBytes (blockSize / 8);
}
}
}