private byte[] DecryptIndexBlock(string encryptionKey)
{
byte[] indexBlock;
using (var reader = new BinaryReader(_stream, Encoding.UTF8, true))
{
_stream.Seek(_indexOffset, SeekOrigin.Begin);
indexBlock = reader.ReadBytes((int)_indexSize);
try
{
var aes = new AesManaged
{
Mode = CipherMode.ECB,
Padding = PaddingMode.Zeros,
Key = encryptionKey.ConvertHexStringToBytes()
};
aes.CreateDecryptor().TransformBlock(indexBlock, 0, indexBlock.Length, indexBlock, 0);
}
catch (Exception ex) when(ex is ArgumentException || ex is FormatException || ex is CryptographicException)
{
_entryTable = null;
throw new IncorrectEncryptionKeyException();
}
}
return(indexBlock);
}
private void ReadEntries()
{
_entryTable = new PakEntryTable();
using (var reader = new BinaryReader(_stream, Encoding.UTF8, true))
{
_stream.Seek(_indexOffset, SeekOrigin.Begin);
MountPoint = reader.ReadFString();
int fileCount = reader.ReadInt32();
for (int i = 0; i < fileCount; i++)
{
string fileName = reader.ReadFString();
long metadataOffset = _stream.Position;
PakEntryMetadata metadata = ReadEntryMetadata(reader);
metadata.MetadataOffset = metadataOffset;
metadata.FileName = fileName;
_entryTable.Add(metadata);
}
}
}
public static VirtualFileSystem CreateGraph(PakEntryTable entries)
{
var graph = new VirtualFileSystem();
foreach (PakEntryMetadata entry in entries)
{
var currentFolder = graph.Root;
string[] segments = entry.FileName.Split('/');
var path = new StringBuilder();
for (int i = 0; i < segments.Length - 1; i++)
{
path.Append("/" + segments[i]);
if (!currentFolder.Subfolders.ContainsKey(segments[i]))
{
currentFolder.Subfolders.Add(segments[i], new VirtualFolder(path.ToString()));
}
currentFolder = currentFolder.Subfolders[segments[i]];
}
currentFolder.Files.Add(segments[segments.Length - 1], entry);
}
return(graph);
}
private void ReadEntries(string encryptionKey)
{
if (!IsIndexEncrypted)
{
ReadEntries();
return;
}
_entryTable = new PakEntryTable();
byte[] indexBlock = DecryptIndexBlock(encryptionKey);
using (var reader = new BinaryReader(new MemoryStream(indexBlock)))
{
try
{
MountPoint = reader.ReadFString();
int fileCount = reader.ReadInt32();
for (int i = 0; i < fileCount; i++)
{
string fileName = reader.ReadFString();
long metadataOffset = reader.BaseStream.Position;
PakEntryMetadata metadata = ReadEntryMetadata(reader);
metadata.MetadataOffset = metadataOffset + _indexOffset;
metadata.FileName = fileName;
_entryTable.Add(metadata);
}
}
catch (ArgumentOutOfRangeException) // reader.ReadFString will throw this if MountPoint cannot be read
{
_entryTable = null;
throw new IncorrectEncryptionKeyException();
}
}
}