ZenHAX

Hello, this is my first time in here, sorry for bad English skill.
This is the follow up from:
- viewtopic.php?f=6&t=16080
- viewtopic.php?f=6&t=16544

So... in early time (before Season 6), Cookie Run's MIDI file is encrypted with Salsa20.
simontime, a Nintendo game reverse engineering guy, who successfully decrypted MIDI file, wrote the program in C
Key and IV are:

const uint8_t key[] =
{
   0xF7, 0x9B, 0xF7, 0x33, 0xF2, 0x3F, 0x9D, 0x7A,
   0xF2, 0xA2, 0x91, 0xCB, 0x4D, 0xCB, 0x5E, 0x49,
   0x63, 0xE6, 0xA8, 0x71, 0xE0, 0x51, 0x2C, 0xE1,
   0x46, 0xBD, 0x03, 0x67, 0x93, 0x56, 0xA4, 0x73
};

const uint8_t iv[] =
{
   0xBC, 0x79, 0xCC, 0x75, 0x91, 0xB4, 0x8D, 0x70
};

However not after long...
When game step into Season 6, everything changed. The new encryption step in.
There's a rumor that:



So, I what have I found:

A lot of encrypted MIDI have this header:

29 01 38 FD B3 29 45 5E E8

which mean

)
8ý³)E^è

Thank to asdf_#4749 on Discord for this discover:


I begin to use IDA Pro to decompile .so file in APK file, but... syrupyy (CRK but translated video creator) said:

so yeah, I moved to iOS.

In this case, I'm using IDA Pro 7.5 with Hex-Rays (I don't use >=7.7 because crash)

There's a function called *gb* which you can see. I get into *gb::sound*

Today, I want to thank tungdo0602 for giving me OpenGPT API token since I can't login in Vietnam
I'm using a plugin called Gepetto
Sadly, *gb::sound* can't giving me any infomation + few of them are too long that AI can't explain it.

So... I moved to *gb::crepe*
I found something, but not sound related...
It's called:
- gb::crepe::KeyStore::KeyStore
- gb::crepe::KeyStore::loadKey
- gb::crepe::KeyStore::loadMasterKey

The interesting one is loadKey and loadMasterKey
this is loadKey:

So... this is modified Salsa20?

and this is loadMasterKey:


Another one is *gb::buildConfig::crepeKeystoreMasterIndex*


A few unk_ thing, I clicked on it...


I scroll down a bit and I found this:


I think this is not a key for decrypting MIDI, so I ignore it.


So, I found nothing, or I just ignore a lot of it?
I almost become an autism guy because no one help with. So if you found something, please let me know!

There's my question:
- What kind of encryption it is? (hope that this is not ECC)
- Is their code hidden?
- What is their key and IV?

Also, I'll give you IDA Pro if you want it for research. DM me on Discord: Bang1338#5701
Hope you guy can helping me and us! Thank you!