/// <summary>
/// Decrypts a segment of an EndianReader stream.
/// </summary>
/// <param name="Reader">The EndianReader to read from.</param>
/// <param name="StartPosition">The stream position to decrypt from.</param>
/// <param name="Length">The number of bytes to decrypt.</param>
/// <param name="Key">The decryption key as a string.</param>
/// <returns>A new EndianReader stream containing only the decrypted segment.</returns>
public static EndianReader DecryptSegment(EndianReader Reader, int StartPosition, int Length, string Key)
{
Reader.SeekTo(StartPosition);
if (Length % 16 != 0) Length += 16 - Length % 16;
byte[] data = Reader.ReadBytes(Length);
byte[] bKey = System.Text.Encoding.ASCII.GetBytes(Key);
byte[] XOR = new byte[bKey.Length];
byte[] IV = new byte[bKey.Length];
for (int i = 0; i < bKey.Length; i++)
{
XOR[i] = (byte)(bKey[i] ^ 0xFFA5);
IV[i] = (byte)(XOR[i] ^ 0x3C);
}
var aes = new AesManaged()
{
Mode = CipherMode.CBC,
Key = XOR,
IV = IV,
Padding = PaddingMode.Zeros
};
Stream stream = (Stream)new MemoryStream(aes.CreateDecryptor(aes.Key, aes.IV).TransformFinalBlock(data, 0, data.Length));
return new EndianReader(stream, EndianFormat.Big);
}
private void ReadUTFData(EndianReader br)
{
isUtfEncrypted = false;
br.IsLittleEndian = true;
unk1 = br.ReadInt32();
utf_size = br.ReadInt64();
utf_packet = br.ReadBytes((int)utf_size);
if (utf_packet[0] != 0x40 && utf_packet[1] != 0x55 && utf_packet[2] != 0x54 && utf_packet[3] != 0x46) //@UTF
{
utf_packet = DecryptUTF(utf_packet);
isUtfEncrypted = true;
}
br.IsLittleEndian = false;
}