I hope someone who knows will answer me. After i have unlocked the BootLoader, installed the Rom, can i re-lock the Bootloader?
I'm a bit confused about security if the Bootloader is unlocked, when my phone is stolen, it will be very easy for the thief to get into the phone and use Banking apps on this device.
If you protect your device with /ping/partern, a thief cannot login/unlock the screen
And he cannot even read Data from TWRP bcs the same pin/pattern is required for TWRP to decrypt Data (without the correct pin/pattern, TWRP shows 'scrambled' files, cannot backup, etc)
A thief can, with your unlocked Bootloader, flash a custom ROM and use your phone, but he will have to reformat Data - hence he couldn't obtain your Data that way either
(If flashing MIUI, official or Xiaomi.eu, he will be asked for your MIUI password - hence he could not even use the phone)
And if you ever want to relock Bootloader, flash the official MIUI fastboot version, format Data, then relock (it will format once again) - then you can enjoy with a 'safe' phone
It applies to all phones (ok, except the ancient Androids), to flash custom ROMs, Bootloader must be unlocked, and cannot be relocked without returning first to the official firmware (relocking either not allowed or bricking the phone)
And also about encrypted Data - but there some custom ROMs where developers disable Data encryption, and that's then dangerous when phone is lost or stolen