private static (string vCode1, string vCode2, uint indexRngSeed) LoadKeys(string startFolder)
{
// I had a stroke and decided to make everything as "functional" as possible, sorry.
var pairs = new[] {
new ResourceId("KEY_CODE"),
new ResourceId("V_CODE"),
new ResourceId("V_CODE2"),
};
// assuming all *.int files are in game exe folder
foreach (string file in Directory.GetFiles(startFolder, "*.exe"))
{
using (var resInfo = new ResourceInfo(file, true)) {
// only attempt files where all resources are present
if (!pairs.All(pair => resInfo.ResourceTypes.Any(resType => resType == pair)))
{
continue;
}
byte[][] resData = pairs.Select(pair => resInfo[pair].First().ToBytes()).ToArray();
Debug.Assert(resData.Skip(1).All(x => x.Length == 16), "VCodes were not 16 bytes long");
var bf = new BlowfishDecryptor(new Blowfish(resData[0].Select(x => (byte)(x ^ 0xCD)).ToArray()));
var vCode1 = bf.TransformFinalBlock(resData[1], 0, 16).ToCString();
var vCode2 = bf.TransformFinalBlock(resData[2], 0, 16).ToCString();
return(vCode1, vCode2, GenerateIndexRngSeed(vCode2));
}
}
throw new Exception("Couldn't find game executable");
}
public IEnumerable <IExtractableFile> LoadFilesFromArchive(string inputArchive)
{
// find keys from exe, if not present yet
if (key1 is null || key2 is null)
{
(key1, key2, indexRngSeed) = LoadKeys(Path.GetDirectoryName(inputArchive));
}
using (var fs = File.OpenRead(inputArchive))
using (var br = new BinaryReader(fs)) {
string magic = Encoding.ASCII.GetString(br.ReadBytes(4));
if (magic != FileMagic)
{
throw new InvalidMagicException();
}
int entries = br.ReadInt32();
BlowfishDecryptor dec = null;
for (int i = 0; i < entries + 1; i++)
{
string fileName = br.ReadBytes(0x40).ToCString();
ulong read = br.ReadUInt64();
if (fileName == "__key__.dat")
{
// don't make key multiple times
if (!(dec is null))
{
continue;
}
uint key = MersenneTwister.GenRand((uint)(read >> 32));
dec = new BlowfishDecryptor(new Blowfish(BitConverter.GetBytes(key)));
continue;
}
if (dec is null)
{
throw new Exception("First file entry wasn't encryption key");
}
fileName = DeobfuscateFileName(fileName, (uint)unchecked (indexRngSeed + i));
read += (ulong)i;
var newBytes = dec.TransformFinalBlock(BitConverter.GetBytes(read), 0, 8);
uint pos = BitConverter.ToUInt32(newBytes, 0);
uint len = BitConverter.ToUInt32(newBytes, 4);
yield return(new EncryptedFileSlice(fileName, pos, len, inputArchive, dec));
}
}
}
