private static void Main(string[] args)
{
// Check if enough args were passed
if (args.Length != 2)
{
Console.WriteLine("NisasystSharp <game path> <file path>" +
"\nExample: NisasystSharp Mush/ActorDb.release.byml C:\\Blitz\\ActorDb.Release.byml");
return;
}
using (var file = File.OpenRead(args[1]))
using (var reader = new BinaryReader(file))
{
// Length of the file, minus the "nisasyst" magic
var len = (int)file.Length - 8;
// Seek to the magic numbers
file.Position = len;
// Verify the magic numbers
if (reader.ReadUInt64() != 0x747379736173696e)
{
// This isn't a valid file
Console.WriteLine("This file isn't a nisasyst container");
return;
}
// Move back to the beginning of the file
file.Position = 0;
// Create a CRC32 over the game path, and a new SeadRandom instance using the seed
var seadRandom = new SeadRand(Crc32(args[0]));
// Create the encryption key and IV
byte[] key = CreateSequence(seadRandom), iv = CreateSequence(seadRandom);
using (var ms = new MemoryStream())
using (var aes = new AesCryptoServiceProvider()
{
Mode = CipherMode.CBC, Padding = PaddingMode.PKCS7
})
{
using (var crypt = aes.CreateDecryptor(key, iv))
File.WriteAllBytes($"{args[1]}.decrypted", crypt.TransformFinalBlock(reader.ReadBytes(len), 0, len));
Console.WriteLine("Wrote decrypted file");
}
}
}
private static byte[] CreateSequence(SeadRand random)
{
// Create byte array
var sequence = new byte[16];
// Create each byte
for (int i = 0; i < sequence.Length; i++)
{
// Create empty byte string
var byteString = string.Empty;
// Get characters from key material
byteString += KeyMaterial[random.GetU32() >> 24];
byteString += KeyMaterial[random.GetU32() >> 24];
// Parse the resulting byte
sequence[i] = Convert.ToByte(byteString, 16);
}
// Return the sequence
return(sequence);
}
