GARbro-mirror/ArcFormats/Crowd/ImageGAX.cs

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2016-07-22 10:51:12 +08:00
//! \file ImageGAX.cs
//! \date Fri Jul 22 04:07:09 2016
//! \brief ANIM encrypted image.
//
// 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.ComponentModel.Composition;
using System.IO;
using System.Security.Cryptography;
namespace GameRes.Formats.Crowd
{
internal class GaxMetaData : ImageMetaData
{
public byte[] Key;
}
[Export(typeof(ImageFormat))]
public class GaxFormat : ImageFormat
{
public override string Tag { get { return "GAX"; } }
public override string Description { get { return "ANIM encrypted image"; } }
public override uint Signature { get { return 0x01000000; } }
public override ImageMetaData ReadMetaData (Stream stream)
{
var key = new byte[0x10];
stream.Position = 4;
if (key.Length != stream.Read (key, 0, key.Length))
return null;
using (var enc = new InputProxyStream (stream, true))
using (var input = new CryptoStream (enc, new GaxTransform (key), CryptoStreamMode.Read))
{
var info = Png.ReadMetaData (input);
if (null == info)
return null;
return new GaxMetaData
{
OffsetX = info.OffsetX,
OffsetY = info.OffsetY,
Width = info.Width,
Height = info.Height,
BPP = info.BPP,
Key = key,
};
}
}
public override ImageData Read (Stream stream, ImageMetaData info)
{
var meta = (GaxMetaData)info;
using (var enc = new StreamRegion (stream, 0x14, true))
using (var input = new CryptoStream (enc, new GaxTransform (meta.Key), CryptoStreamMode.Read))
return Png.Read (input, info);
}
public override void Write (Stream file, ImageData image)
{
throw new System.NotImplementedException ("GaxFormat.Write not implemented");
}
}
internal sealed class GaxTransform : ICryptoTransform
{
private const int BlockSize = 16;
private byte[] m_key;
public bool CanReuseTransform { get { return false; } }
public bool CanTransformMultipleBlocks { get { return true; } }
public int InputBlockSize { get { return BlockSize; } }
public int OutputBlockSize { get { return BlockSize; } }
public GaxTransform (byte[] key)
{
m_key = key.Clone() as byte[];
}
public int TransformBlock (byte[] inputBuffer, int inputOffset, int inputCount,
byte[] outputBuffer, int outputOffset)
{
int inputEnd = inputOffset + inputCount;
while (inputOffset < inputEnd)
{
int k;
for (k = 0; k < BlockSize && inputOffset < inputEnd; ++k)
{
outputBuffer[outputOffset++] = (byte)(inputBuffer[inputOffset++] ^ m_key[k]);
}
if (k < BlockSize)
break;
byte m = outputBuffer[outputOffset-2];
switch (m & 7)
{
case 0:
m_key[0] += m;
m_key[3] += (byte)(m + 2);
m_key[4] = (byte)(m_key[2] + m + 11);
m_key[8] = (byte)(m_key[6] + 7);
break;
case 1:
m_key[2] = (byte)(m_key[9] + m_key[10]);
m_key[6] = (byte)(m_key[7] + m_key[15]);
m_key[8] += m_key[1];
m_key[15] = (byte)(m_key[3] + m_key[5]);
break;
case 2:
m_key[1] += m_key[2];
m_key[5] += m_key[6];
m_key[7] += m_key[8];
m_key[10]+= m_key[11];
break;
case 3:
m_key[9] = (byte)(m_key[1] + m_key[2]);
m_key[11] = (byte)(m_key[5] + m_key[6]);
m_key[12] = (byte)(m_key[7] + m_key[8]);
m_key[13] = (byte)(m_key[10] + m_key[11]);
break;
case 4:
m_key[0] = (byte)(m_key[1] + 0x6F);
m_key[3] = (byte)(m_key[4] + 0x47);
m_key[4] = (byte)(m_key[5] + 0x11);
m_key[14] = (byte)(m_key[15] + 0x40);
break;
case 5:
m_key[2] += m_key[10];
m_key[4] = (byte)(m_key[5] + m_key[12]);
m_key[6] = (byte)(m_key[8] + m_key[14]);
m_key[8] = (byte)(m_key[0] + m_key[11]);
break;
case 6:
m_key[9] = (byte)(m_key[1] + m_key[11]);
m_key[11] = (byte)(m_key[3] + m_key[13]);
m_key[13] = (byte)(m_key[5] + m_key[15]);
m_key[15] = (byte)(m_key[7] + m_key[9]);
goto case 7;
case 7:
m_key[1] = (byte)(m_key[5] + m_key[9]);
m_key[2] = (byte)(m_key[6] + m_key[10]);
m_key[3] = (byte)(m_key[7] + m_key[11]);
m_key[4] = (byte)(m_key[8] + m_key[12]);
break;
}
}
return inputCount;
}
public byte[] TransformFinalBlock (byte[] inputBuffer, int inputOffset, int inputCount)
{
byte[] outputBuffer = new byte[inputCount];
for (int i = 0; i < inputCount; ++i)
{
outputBuffer[i] = (byte)(inputBuffer[inputOffset+i] ^ m_key[i]);
}
return outputBuffer;
}
public void Dispose ()
{
System.GC.SuppressFinalize (this);
}
}
}