GARbro-mirror/ArcFormats/Bruns/ImageEENC.cs

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2016-06-19 07:06:09 +08:00
//! \file ImageEENC.cs
//! \date Sat Jun 18 06:26:23 2016
//! \brief SepterApp encrypted images.
//
// 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 System;
using System.ComponentModel.Composition;
using System.IO;
using GameRes.Compression;
using GameRes.Utility;
namespace GameRes.Formats.Bruns
{
internal class EencMetaData : ImageMetaData
{
public uint Key;
public ImageMetaData Info;
public ImageFormat Format;
public bool Compressed;
}
[Export(typeof(ImageFormat))]
public class EencFormat : ImageFormat
{
public override string Tag { get { return "EENC"; } }
public override string Description { get { return "Bruns system encrypted image"; } }
public override uint Signature { get { return 0x434E4545; } } // 'EENC'
static readonly uint EencKey = 0xDEADBEEF;
public EencFormat ()
{
Extensions = new string[] { "brs", "png", "bmp" };
Signatures = new uint[] { 0x434E4545, 0x5A4E4545 }; // 'EENC', 'EENZ'
}
public override ImageMetaData ReadMetaData (Stream stream)
{
var header = new byte[8];
if (8 != stream.Read (header, 0, 8))
return null;
bool compressed = 'Z' == header[3];
uint key = LittleEndian.ToUInt32 (header, 4) ^ EencKey;
Stream input = new StreamRegion (stream, 8, true);
try
{
input = new EencStream (input, key);
if (compressed)
{
input = new ZLibStream (input, CompressionMode.Decompress);
input = new SeekableStream (input);
}
var format = FindFormat (input);
if (null == format)
return null;
return new EencMetaData
{
Width = format.Item2.Width,
Height = format.Item2.Height,
BPP = format.Item2.BPP,
Key = key,
Info = format.Item2,
Format = format.Item1,
Compressed = compressed,
};
}
finally
{
input.Dispose();
}
}
public override ImageData Read (Stream stream, ImageMetaData info)
{
var meta = (EencMetaData)info;
meta.Info.FileName = info.FileName;
Stream input = new StreamRegion (stream, 8, true);
try
{
input = new EencStream (input, meta.Key);
if (meta.Compressed)
input = new ZLibStream (input, CompressionMode.Decompress);
return meta.Format.Read (input, meta.Info);
}
finally
{
input.Dispose();
}
}
public override void Write (Stream file, ImageData image)
{
throw new System.NotImplementedException ("EencFormat.Write not implemented");
}
}
internal class EencStream : InputProxyStream
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{
uint m_key;
public EencStream (Stream main, uint key, bool leave_open = false)
: base (main, leave_open)
{
m_key = key;
}
public override int Read (byte[] buffer, int offset, int count)
{
int pos = (int)Position & 3;
int read = BaseStream.Read (buffer, offset, count);
for (int i = 0; i < read; ++i)
{
buffer[offset+i] ^= (byte)(m_key >> (pos << 3));
pos = (pos + 1) & 3;
}
return read;
}
public override int ReadByte ()
{
int pos = (int)Position & 3;
int b = BaseStream.ReadByte();
if (-1 != b)
b ^= (byte)(m_key >> (pos << 3));
return b;
}
}
}