What Knox is
Knox is a security system that has been included in Samsung phones since Android 4.3. In recent years its functions have expanded and it is now a platform for services with privacy.
The overall idea of Knox is to increase the security of the terminal and, in case of professional use, to restrict access to certain parts of the smartphone. That’s right and that’s how Samsung’s Knox works.
What exactly is Knox?
Samsung introduced this feature in 2013 and since then we can find it on their Galaxy devices.
Knox is a platform with several applications and services in order to protect hardware, software and user data thanks to an encrypted container that creates a safe execution and storage space.
Knox was designed primarily for the professional field, with the aim of promoting the so-called BYOD (Bring Your Own Device) providing tools that eliminate risks, such as the filtering of confidential data or industrial espionage.
Knox also monitors the security status of the device. Being responsible for voiding the warranty if an unofficial software is flashed (through Odin, for example) in the Galaxy.
In recent years this protection against software that Samsung does not install on our devices is protected by an e-fuse. We will tell you more details about the e-fuse and the guarantee in the following section.
In addition to controlling the software we have other services associated with Knox such as Secure Folder.
Until June 2017 there was another similar service called My Knox but Samsung forced users to migrate to the new service.
With Secure Folder we can have applications and files encrypted and synchronized in the Samsung cloud. If we install a recovery or rotate the device you will no longer be able to access Secure Folder in the terminal.
Knox, warranty and flash counter
Samsung may refuse to repair our device, even if it is still under warranty, on the grounds that the damage was caused by an unofficial modification that altered the factory condition of the terminal.
As Chainfire stated, this is a great loss for the user since the manufacturer forces to use only their software on the device.
The warranty is forfeited when the famous “flash counter” rises from zero. The normal state with warranty is: “WARRANTY VOID: 0 (0x0000)”. To see the status of the counter just enter the download mode of the device.
Since 2013 the Samsung Galaxy devices have built-in an e-fuse (a fuse) that once modified the device with an unofficial software (rooteado, custom recovery, custom rom, even official firmware through Odin), Knox blows this fuse and the flash counter goes up to 1 (0x1). So there’s no way to go back and you lose the warranty immediately.
In the first models that incorporated KNOX (Galaxy S3 for example) the flash counter was a piece of software and not hardware.
Therefore there was a possibility to reset the flash counter to zero but currently it is impossible.
How to disable or remove Knox
Knox is a set of system applications and furthermore cannot simply be disabled. Removing Knox from the device is dangerous and may not restart.
To remove it we must access the system files and remove some of its applications. To do this we need to be root on the device, so this process would void the warranty.
Many users have reported that after deleting the list of applications that manage Knox the device has not been able to restart.
This seems to be because Knox ascertains whether the system is intact and allows the system to boot. For this case the only solution is to install a custom rom.
If you want to have a free Knox system my recommendation is to install a custom rom.