Google has unveiled a new security feature for its Pixel phones and tablets to ensure the models you buy have not been tampered with.
Pixel Binary Transparency allows users to self-check that the Android factory image is genuine and hasn’t been tampered with anywhere in the supply chain before actually purchasing the phone.
It expands on Android Verified Boot, which ensures that the stock code actually comes from the hardware vendor. For Google phones, it checks that the code on the phone is the same as verified by Google to ensure there are no backdoors in the software.
Binary transparency
Google says Binary Transparency will let users verify that Google’s official factory image is actually on their phone, which ensures that “attackers have not introduced themselves anywhere in the source code, build process, or release aspects of the software supply chain.”
It uses a public cryptographic log to prove mathematically that their devices are free of tampered code. Google has provided instructions to users on how to verify that their image is the same as listed in the log, which involves “extracting the relevant metadata and then comparing their recalculated root hash with the root hash in the published checkpoint.”
“If they match, the Pixel owner can be assured of some of the protections exemplified in the Threat Model,” it added.
The log uses a Merkle tree making it impossible to modify or delete the log; it’s just adding. If an image has been tampered with by hackers, it’s obvious because it no longer matches the metadata in the log.
Android Verified Boot is more user-friendly to ensure your device is running genuine Android software, with Binary Transparency designed for more power users.
Google also said it will build on the new feature even further in the future, “to make even more security data transparent to users, providing proactive assurance for a device’s other code execution outside of the factory image.”