33 lines
1.8 KiB
Markdown
33 lines
1.8 KiB
Markdown
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## Anti-Rollback Protection explained
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Anti-Rollback Protection (ARP) was introduced by Google in Android 8.0 Oreo and they made its implementation mandatory for devices launching with Android 9.0 Pie. ARP is a security countermeasure aiming to prevent devices from booting older, less-secure versions of Android. In Google's implementation, ARP is disabled if the bootloader is unlocked, whereas on Xiaomi devices it cannot be disabled once it's enabled by a ROM that implements it. Xiaomi likely made this decision to stop resellers from exploiting vulnerabilities found in older versions of MIUI.
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### Checking if ARP is enabled
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1. Download and launch the Xiaomi ADB/Fastboot Tools from [here](tools.md).
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2. Connect the device to your computer and load it in Fastboot mode. The device info should appear in the application.
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For details, see the instructions on GitHub.
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If don't get any number for anti version, ARP isn't enabled. If you get a number, ARP is enabled.
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### Anti version explained
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Having an anti version means that you cannot flash whatever ROM you want, only ROMs that have an anti version equal to or higher than the device's.
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* Flashing a ROM with an anti version higher than the device's will set it to the higher value.
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* Flashing a ROM with an anti version equal to the device's won't change anything.
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* Flashing a ROM with an anti version lower than the device's will result in a hard brick.
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For now, only Fastboot ROMs check for anti version and act accordingly. They will abort without making any changes if the device's anti version is higher than its own.
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Custom ROMs are unaffected by ARB and flashing them won't brick the device or change the anti version.
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### ARP-enabled devices
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* Mi 6X (wayne)
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* Mi 8 (dipper)
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* Mi Max 3 (nitrogen)
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* Redmi 6 Pro (sakura)
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* Redmi Note 5 (whyred)
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