// See: Bin2Object/BinaryObjectStream.cs
public void PreProcessMetadata(BinaryObjectStream stream, PluginPreProcessMetadataEventInfo info)
{
// Example: check if metadata has correct signature
if (stream.ReadUInt32() != Il2CppConstants.MetadataSignature)
{
Console.Error.WriteLine("Metadata signature is invalid");
}
// The file is loaded into memory so you can make edits without affecting the file
// See PreProcessImage below for information about using BinaryObjectStream for de-obfuscation
// Set info.IsStreamModified if you change the stream contents
}
// This executes as soon as the raw global-metadata.dat has been read from storage,
// before any attempt is made to analyze its contents
public void PreProcessMetadata(BinaryObjectStream stream, PluginPreProcessMetadataEventInfo info)
{
stream.Position = 21;
var key = presetKey.Value == "custom"? customKey.Value : PresetKeys[presetKey.Value];
if (string.IsNullOrEmpty(key))
{
throw new ArgumentException("Game version or decryption key must be specified");
}
var sig = stream.ReadBytes(4);
sig = sig.Select((b, i) => (byte)(b - key[i % key.Length])).ToArray();
if (BitConverter.ToUInt32(sig) != Il2CppConstants.MetadataSignature)
{
return;
}
PluginServices.For(this).StatusUpdate("Decrypting metadata");
// Subtract key bytes from metadata bytes, skipping the first bytes,
// and cycling through the key bytes repeatedly
var bytesToSkipAtStart = 21;
var length = stream.Length;
var bytes = stream.ToArray();
var keyBytes = Encoding.ASCII.GetBytes(key);
for (int index = 0, pos = bytesToSkipAtStart; pos < length; index = (index + 1) % key.Length, pos++)
{
bytes[pos] -= keyBytes[index];
}
// We replace the loaded global-metadata.dat with the newly decrypted version,
// allowing Il2CppInspector to analyze it as normal
stream.Write(0, bytes.Skip(bytesToSkipAtStart).ToArray());
info.IsStreamModified = true;
}
// This executes as soon as the raw global-metadata.dat has been read from storage,
// before any attempt is made to analyze its contents
// We use it to call UnityPlayer.dll to decrypt the file in memory
public void PreProcessMetadata(BinaryObjectStream stream, PluginPreProcessMetadataEventInfo info)
{
// Assume that your plugin is enabled regardless of what is loading
// Therefore, we don't want to process global-metadata.dat files that are not for us!
// miHoYo metadata has an invalid signature at the start of the file so we use that as the criteria
IsOurs = stream.ReadUInt32(0) != Il2CppConstants.MetadataSignature;
if (!IsOurs)
{
return;
}
// The DWORD 0x4008 bytes from the end should be an offset to itself
var lastBlockPointer = stream.Length - 0x4008;
IsOurs = stream.ReadUInt32(lastBlockPointer) == lastBlockPointer;
if (!IsOurs)
{
return;
}
// Tell the user what is happening in case it takes a while
PluginServices.For(this).StatusUpdate("Decrypting metadata");
// Create a delegate which internally is a function pointer to the DecryptMetadata function in the DLL
var pDecryptMetadata = (DecryptMetadata)Marshal.GetDelegateForFunctionPointer(ModuleBase + Offsets[game.Value].DecryptMetadata, typeof(DecryptMetadata));
// Call the delegate with the encrypted metadata byte array and length as arguments
var decryptedBytesUnmanaged = pDecryptMetadata(stream.ToArray(), (int)stream.Length);
// Copy the decrypted data back from unmanaged memory to a byte array
metadataBlob = new byte[stream.Length];
Marshal.Copy(decryptedBytesUnmanaged, metadataBlob, 0, (int)stream.Length);
// Genshin Impact adds some spice by encrypting 0x10 bytes for every 'step' bytes of the metadata
// with a simple XOR key, so we need to apply that too
if (game.Value.StartsWith("genshin-impact"))
{
var key = new byte [] { 0xAD, 0x2F, 0x42, 0x30, 0x67, 0x04, 0xB0, 0x9C, 0x9D, 0x2A, 0xC0, 0xBA, 0x0E, 0xBF, 0xA5, 0x68 };
// The step is based on the file size
var step = (int)(stream.Length >> 14) << 6;
for (var pos = 0; pos < metadataBlob.Length; pos += step)
{
for (var b = 0; b < 0x10; b++)
{
metadataBlob[pos + b] ^= key[b];
}
}
}
// We replace the loaded global-metadata.dat with the newly decrypted version,
// allowing Il2CppInspector to analyze it as normal
stream.Write(0, metadataBlob);
// Some types have reordered fields - these calls tell Il2CppInspector what the correct field order is
// See MappedTypes.cs for details
stream.AddObjectMapping(typeof(Il2CppInspector.Il2CppGlobalMetadataHeader), typeof(Il2CppGlobalMetadataHeader));
stream.AddObjectMapping(typeof(Il2CppInspector.Il2CppTypeDefinition), typeof(Il2CppTypeDefinition));
stream.AddObjectMapping(typeof(Il2CppInspector.Il2CppMethodDefinition), typeof(Il2CppMethodDefinition));
stream.AddObjectMapping(typeof(Il2CppInspector.Il2CppFieldDefinition), typeof(Il2CppFieldDefinition));
stream.AddObjectMapping(typeof(Il2CppInspector.Il2CppPropertyDefinition), typeof(Il2CppPropertyDefinition));
// We tell Il2CppInspector that we have taken care of the metadata
// IsStreamModified marks the original data stream as modified so that the user is able to save the changes
// SkipValidation tells Il2CppInspector not to check this global-metadata.dat for validity;
// if we don't set this, it will report that the metadata is invalid
info.IsStreamModified = true;
info.SkipValidation = true;
}
