[Help] HFS signing

HFS signing

Okay, so is there a way to sign hfs files without hfssign? I wouldn't need a full answer really, if you wouldn't wanna say. Just a yes or no.
VERY new to doing this kind of stuff. So any and all information is very appreciated ^^

Thanks

Fovea is to my knowledge the only one that has publicly made a hfs signer, is there other ways? Perhaps but nothing public. In short, No.

Alrighty, thanks. I'll look more into it and maybe just try and make my own stuff. Would seem to be the more useful and quick way.

Originally Posted by JakeyDesu

Alrighty, thanks. I'll look more into it and maybe just try and make my own stuff. Would seem to be the more useful and quick way.

Not to simplify or belittle Fovea's hfs signer, but all he did was decode the encryption on the files. If you can figure out how to replicate the authentication for the signatures, then that's effectively the next version of the .hfs signer. Once you figure out how the encryption works, it's pretty easy. But cracking the encryption may require a combination of certain creativity and skill that few possess, which is the difficult part.

The Force is strong with @Fovea!

How it was done:

Place a malformed file inside the hfs folder, and produce the associated error.
Find where in the code the error is produced.
The error raising code is inside a virtual machine, so find out where the VM entry is.
Deobfuscate the virtual machine, and reinterpret the bytecode.
Disassemble the bytecode and find out how the error is raised.
The error is raised by some sort of checksum, so replicate the checksum (fortunately it is the same checksum used in my first hfssign).
Find out where the stored checksum is located (inside UpToDate.info).
Understand UpToDate.info file format, it seems to be encrypted.
Disassemble and replicate the decryption/encryption algorithm used on UpToDate.info.
With the plaintext (decrypted file), understand how the file is formatted (e.g., determine structures and their fields).
Use the information gained through disassembly to write hfssign.

Steps 3 and 4 are the hardest.

Wow, okay well seems kind of intimidating to someone like me with limited knowledge for this kind of stuff. Do you know of any books or websites that could help me further understand? Thank you for the steps though, I really appreciate it. It'll help me in the process of learning ^_^

Also hope I'm not asking for too much, since you already basically explained the whole thing to me, and in my ignorance ask for more hah.

HelpHFS signing

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