![]() ![]() This signature is sent to the device along Since an attacker could use it to sign malicious images which all Tamper-proof place such as read-only memory or a verified key We make sure that the public key is distributed on each device in a How does an image get signed initially, andįirst, on a host machine, we create a key pair. Script or with a more sophisticated user interface. Public keys to be provided by the user, perhaps by inserting an SDĬard containing the key. A more sophisticated scheme would allow the (often called the flattened device tree or FDT). Include the initial public key, held in U-Boot's device Read-only media during manufacture or perhaps protected by on-chipĬrypto using its own signing scheme. In principle this chain can be any length,īut there must be an initial trusted image ("root of Itself to be updated with the firmware without risking having an unbootable Image containing a new U-Boot, then boot that. Images can be chained one after the otherĪnd signed in reverse order either using the same keys or sub-keys On the device we can obtain an image and verify it was We can create a key, hash an image, sign that hash, and publish the It fits in seamlessly with the existing imageįamiliar technologies: cryptographic hashingĭistribute images and have them verified on a device. U-Boot's new verified boot feature providesĪ mechanism for verifying images while still allowing them Implement a form of secure boot which we will call "verified #U BOOT SECURE BOOT VERIFICATION#U-Boot 2013.07 introduces a feature allowingįor the verification of a kernel and other images. The firmware write-protection, so it is possible to disable verified #U BOOT SECURE BOOT INSTALL#This can be addressed by allowing the user to install keys as UEFI does, or havingĪs an example of the latter, some Chrome OS devices have a mechanical screw The downside (at least from a technical user's point of view) may be this manufacturer control. #U BOOT SECURE BOOT SOFTWARE#Software running on devices in the field. Software updates are safe, and can help manufacturers control the It helps to prevent malware from inserting itself into the boot Widespread use, some form of verified boot is useful for similar It provides a way to ensure that only software signed byįor embedded systems that don't use Chrome OS and where UEFI is not in Years has resulted in a lot of attention to its Secure Bootįeature. ![]() The widespread use of UEFI on PCs in recent That feature is an integral part of the overall security architecture. More systems these days are using some type of verified boot mechanism to ensure that only theĮxpected code can be used to boot the system.Ĭhrome OS uses verified boot to ensure that only approved images canīe used on the Chromebook (in normal, non-developer mode). This article was contributed by Simon Glass ![]()
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