ViRb3 / fouldecrypt

A lightweight and simpling iOS binary decryptor

FoulDecrypt

It's also available in my Cydia repo: http://repo.misty.moe. FoulDecrypt supports iOS 13.5 and later, and has been tested on iOS 14.2, 14.3 and 13.5 (both arm64 and arm64e).

Note: for unsupported versions, it has chances to panic the device, beware ;)

Why FoulDecrypt

1. Fully static

Thanks to FlexDecrypt and FoulPlay we know there's a mremap_encrypted syscall, although AAPL already released full source code for this syscall now.

However, neither of them can actually get mremap_encrypted to work. That's because mremap_encrypted cannot accept non-aligned address, making it useless for most iOS 14 apps.

I managed to fix with kernel read/writing, so now we can achieve clutch's armv7+arm64 multi-arch decryption again in 2021!

2. Simplicity

FlexDecrypt's source code is pretty FAT, bundling the whole swift runtime to just achieve a simple mremap_encrypted.

And at the same time, foulplay independently found the same approach, and implemented it in a much more simple way.

I recompiled the foulplay for iOS, and a wrapper flexdecrypt2 for flexdecrypt.

How to use

Install the correct version:

• fouldecrypt-TFP0 for < iOS 14
• fouldecrypt-LIBKRW if you are running Unc0ver
• fouldecrypt-LIBKERNRW if you are running Taurine

Run fouldecrypt on an encrypted binary.

Credits

@meme: foulplay @JohnCoates: flexdecrypt