Bruteforcing tool for guessing a device password given pwd credidential files and their AES key from the keymaster database.
On older android versions, bruteforcing used to be relatively easy; you could get into the device by removing locksettings.db, or some other files, which unfortunately no longer exist.
Since nougat, encryption has been possible. While on its own it just means we'd have to bruteforce the password, and this was likely the case back in FDE days, modern hardware backed file based encryption required on every new android device is extremely complicated and to my knowledge impossible to simply bruteforce without extracting hardware keys that aren't on any regular phone partition.
This means your data is mostly secure even if your phone is stolen with an unlocked bootloader, but it also means you can't get it back if you forget your password.
The android gatekeeper library talks to a hardware chip that enforces a timeout when an incorrect password is picked too many times; which applies to the recovery partition as well, and TWRP doesn't notify you of this. i found extracting the device keys to bruteforce them separately to be the next best bet.
My initial hope was that at some stage in the process, there is a file which can tell us if the provided user password is correct if we attempt decryption on it.
The first step is to gain access to privileged parts of the filesystem, which means the device bootloader has to be unlocked. Luckily, mtkclient let me use a hardware exploit to do exactly this even though my bootloader was not unlocked previously.
This article explains what I was trying to achieve here.
pwd = generate new password
token = scrypt(pwd, R, N, P, Salt)
Application_id = token || Prehashed value
key = SHA512("application_id" || application_id)
AES_Decrypt(value_leaked_from_keymaster, key)
^ AES GCM decryption tells you if the password is wrong - it's possible to compare it separately
/data/system_de/0/spblob/**from android device - Synthetic password key/data/misc/keystore/user_0/* (android <12), /data/misc/keystore/persistent.sqlite (android >= 12)from android device - AES key for the password to be decrypted. You might need to extract it using SQLite. It's called synthetic_password_XXXXX- openssl
- libscrypt
Keys stored on the filesystem in the keystore are encrypted using an AES key which is on a hardware chip, to my knowledge. Regardless, source code for attempting to decrypt the spblob is there.
If you know how to proceed, please contact me as i still have a phone i need my data from. This repo is here for historical reasons and for anyone who is stupid enough to try this themselves.