Last updated: 09 MAY 2014 #1.0. Samsung have released the latest Galaxy S4 stock firmwares, including Android 4.2.2, MGG onwards, see #1.8, for the International, and all future firmwares such as Android 4.3 and KitKat with locked bootloaders and Knox security flag which are a prerequisite for installing the optional, full, Knox Security app. The actual Knox app is downloaded from the Play Store via an icon on the phone, if required. It is being rolled out across the board to all the latest devices, branded and unbranded, with the exception of the GT-i9505G, Google Play Edition with stock Android firmware. It also comes installed on the latest Galaxy Note 3 and is being rolled out in new firmware updates for the Galaxy S3 and Note 2 as well as some tablets. Their reasoning behind this is to prevent devices with sensitive data (corporate, defence, government, etc: ) from having their data compromised, hence the Knox security. This is to comply with the ever growing security demands from these organisations IT departments for secure BYOD's, (Bring Your Own Device), and is not dissimilar from the Blackberry and Apple security protocols. This means that the latest Samsung devices are now deemed acceptable for use where security is important and increases Samsung's market potential. Samsung have further announced the Knox 2.0 mobile security platform that will come pre-loaded on the Galaxy S5 and will be introduced to older devices running KitKat... Samsung rolls out Knox 2.0 enterprise security suite to Galaxy S5 handsets #1.1. This obviously has implications for rooting and flashing custom ROM's if your workplace demands a secure Knox device. Unfortunately, once the bootloader is locked, reverting to an earlier firmware or nandroid backup is not possible and will not unlock it or remove or reset the Knox flag and can render it unusable with loss of Wi-Fi and/or sound and may require a repair to get it working again in some cases. #1.2. Flashing the latest Samsung stock Android firmwares will overwrite your system files and kernel as well as locking the bootloader, if not already locked. If you are flashing this to an already rooted phone, it will un-root you and, currently, there is no way to re-root and flash a custom recovery or ROM without tripping the Knox flag and rendering it unusable as a BYOD for organisations that require an untouched Knox flag for security. It also means that if you have apps that rely on root, such as SuperSU, you will not be able to uninstall them. Therefore, if you are going to install a stock Samsung, Knox enabled firmware to a rooted phone, you should first fully un-root and uninstall any root associated apps prior to updating. #1.3. In short... if you are on Knox Firmware then you are currently screwed for custom ROM's and recoveries as the Knox flag will be tripped and your device will no longer be Knox secure as a BYOD if your workplace requires it. Also, there is no possibility of going back to a pre Knox/unlocked bootloader firmware or nandroid backup as this will trip the Knox flag also. #1.4. If you are on Knox enabled firmware and wish to view your Knox counter status, go into Download Mode and the Knox flag is shown in the list at the top left of the screen. If, "KNOX WARRANTY VOID:", is showing as 0x0 then you have not tripped the Knox flag. If it is showing as 0x1, your Knox flag is permanently blown and your phone is no longer suitable for Knox security purposes. #1.5 There is a ray of hope for those who wish to update to Android 4.3 and are rooted in that dev's for the International phones have released custom firmwares for Android 4.3 & 4.4.2 that do not already have the locked bootloader and Knox Security. However, these are only available to those that do not already have Knox firmware installed and will not comply with the Knox security protocols if your place of work requires them. #1.6. CF-Auto-Root by chainfire and Root de la Vega claims that they can root Knox enabled devices but do not mention custom recovery or custom ROM flashing. Use at your own risk. There are also reorts that Voodoo's, OTA RootKeeper, has kept root on phones that are rooted and have updated OTA. Although it is not supporting 4.3 officially and may not work on the new 4.4, KitKat, release. Potentially leaving you with a rooted phone that you, "may", not be able to update without blowing the Knox flag. #1.7. The following article by Galen Gruman in Info World, lifts the lid on the new Knox security feature and goes into a lot more detail regarding its future use, (oh yes, there's more to come), on phones and tablets and why some carriers may not even implement it fully... The truth about Samsung Knox for Android security The higher-level security technology for select Android devices isn't really available yet, despite the hype #1.8. Samsung releases are categorised as follows:- M = year = 2013 (13th letter of alphabet) E = Month of year (May in this case, 5th letter of the alphabet) A = Release of that month (10th for, "A", as they start 1-9 first, before letters) Therefore, MEA is pre MGG, (2013, July, 16th release), and is before Knox. Only stock Samsung firmwares MGG onwards, (with the exception of MH1), have Knox. To locate your firmware version... type *#1234# into the dial pad and look at the last 3 letters/numbers of AP: #1.9. Here are some useful links to explain Knox... What is Samsung Knox? (Comes with a short, simple, self explanatory video) Samsung Knox User Manual/Guide #1.10. There appears to be some confusion as to whether tripping the Knox flag to 0x1 does in fact void your warranty as there are conflicting reports and statements regarding this, as discussed in this xda forum thread... Let's find out if KNOX flag 0:1 does void the phone's warranty or not It would seem that some posters in various locations have received warranty repairs even though their Knox flags were 0x1. #1.11. Finally, Samsung have issued the following statement that seems to indicate that Knox will not be used when considering warranty repairs and that they are maintaining the old status quo of, "Don't ask... don't tell", when it comes to rooting whereby a device on stock firmware and a reset Samsung, hidden, flash counter, (separate from the Knox flag), are OK, a warranty repair is considered. About rooting Samsung KNOX-enabled devices and the KNOX warranty void bit #1.12. There is a bounty being offered for any developer who can successfully reset a tripped Knox flag to 0x0, see #1.4. See thread, here. This currently stands at... US$3,173.