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(Rc4Transform): moved to separate file.

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This commit is contained in:
morkt
2016-10-08 05:01:30 +04:00
parent 122cfc7b91
commit d1060aeda6
3 changed files with 88 additions and 68 deletions
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69
ArcFormats/Dogenzaka/ImageRSA.cs
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@@ -29,6 +29,7 @@ using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using GameRes.Cryptography;
namespace GameRes.Formats.Dogenzaka
{
@@ -89,72 +90,4 @@ namespace GameRes.Formats.Dogenzaka
throw new NotImplementedException ("Rc4PngFormat.Write not implemented");
}
}
public sealed class Rc4Transform : ICryptoTransform
{
private const int StateLength = 256;
private const int BlockSize = 256;
private byte[] m_state = new byte[StateLength];
private int x;
private int y;
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 Rc4Transform (byte[] key)
{
m_key = key;
x = 0;
y = 0;
for (int i = 0; i < StateLength; ++i)
{
m_state[i] = (byte)i;
}
int i1 = 0;
int i2 = 0;
for (int i = 0; i < StateLength; ++i)
{
i2 = ((m_key[i1] & 0xFF) + m_state[i] + i2) & 0xFF;
byte t = m_state[i];
m_state[i] = m_state[i2];
m_state[i2] = t;
i1 = (i1+1) % m_key.Length;
}
}
public int TransformBlock (byte[] inBuf, int inOffset, int inCount,
byte[] outBuf, int outOffset)
{
for (int i = 0; i < inCount; i++)
{
x = (x + 1) & 0xFF;
y = (m_state[x] + y) & 0xFF;
byte t = m_state[x];
m_state[x] = m_state[y];
m_state[y] = t;
outBuf[i+outOffset] = (byte)(inBuf[i + inOffset] ^ m_state[(m_state[x] + m_state[y]) & 0xFF]);
}
return inCount;
}
public byte[] TransformFinalBlock (byte[] inBuf, int inOffset, int inCount)
{
byte[] output = new byte[inCount];
TransformBlock (inBuf, inOffset, inCount, output, 0);
return output;
}
public void Dispose ()
{
GC.SuppressFinalize (this);
}
}
}