// Compressed files start with an array of offsets to make seeking possible
private void LoadBlockPositions()
{
int blockposcount = (int)((_entry.FileSize + _blockSize - 1) / _blockSize) + 1;
// Files with metadata have an extra block containing block checksums
if ((_entry.Flags & MpqFileFlags.FileHasMetadata) != 0)
{
blockposcount++;
}
_blockPositions = new uint[blockposcount];
lock (_stream)
{
_stream.Seek(_entry.FilePos, SeekOrigin.Begin);
BinaryReader br = new BinaryReader(_stream);
for (int i = 0; i < blockposcount; i++)
{
_blockPositions[i] = br.ReadUInt32();
}
}
uint blockpossize = (uint)blockposcount * 4;
/*
* if(_blockPositions[0] != blockpossize)
* _entry.Flags |= MpqFileFlags.Encrypted;
*/
if (_entry.IsEncrypted)
{
if (_entry.EncryptionSeed == 0) // This should only happen when the file name is not known
{
_entry.EncryptionSeed = StormBuffer.DetectFileSeed(_blockPositions[0], _blockPositions[1], blockpossize) + 1;
if (_entry.EncryptionSeed == 1)
{
throw new MpqParserException("Unable to determine encyption seed");
}
}
StormBuffer.DecryptBlock(_blockPositions, _entry.EncryptionSeed - 1);
if (_blockPositions[0] != blockpossize)
{
throw new MpqParserException("Decryption failed");
}
if (_blockPositions[1] > _blockSize + blockpossize)
{
throw new MpqParserException("Decryption failed");
}
}
}
public static void Decrypt(byte[] data, string key)
{
StormBuffer.DecryptBlock(data, StormBuffer.HashString(key, 0x300));
}