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diff --git a/docs/security-blueprint/part-2/1-Image.md b/docs/security-blueprint/part-2/1-Image.md new file mode 100644 index 0000000..453b397 --- /dev/null +++ b/docs/security-blueprint/part-2/1-Image.md @@ -0,0 +1,52 @@ +# Image + +## Image selection + +The boot process shall be uninterruptible and shall irrevocably boot the image +as specified in the boot environment. + +In U-Boot set the "_bootdelay_" environment variable and/or define +`CONFIG_BOOTDELAY` to _-2_. + +<!-- section-config --> + +Domain | _Variable_ / `Config` name | `Value` +---------------------- | -------------------------- | ------- +Boot-Image-Selection-1 | `CONFIG_BOOTDELAY` | `-2` +Boot-Image-Selection-2 | _bootdelay_ | `-2` + +<!-- end-section-config --> + +-------------------------------------------------------------------------------- + +## Image authenticity + +It shall not be possible to boot from an unverified image. The secure boot +feature in U-Boot shall be enabled. The secure boot feature is available from +U-Boot 2013.07 version. To enable the secure boot feature, enable the following +features: + +``` +CONFIG_FIT: Enables support for Flat Image Tree (FIT) uImage format. +CONFIG_FIT_SIGNATURE: Enables signature verification of FIT images. +CONFIG_RSA: Enables RSA algorithm used for FIT image verification. +CONFIG_OF_CONTROL: Enables Flattened Device Tree (FDT) configuration. +CONFIG_OF_SEPARATE: Enables separate build of u-Boot from the device tree. +CONFIG_DEFAULT_DEVICE_TREE: Specifies the default Device Tree used for the run-time configuration of U-Boot. +``` + +Generate the U-Boot image with public keys to validate and load the image. It +shall use RSA2048 and SHA256 for authentication. + +<!-- section-config --> + +Domain | `Config` name | _State_ +------------------------- | ---------------------------- | -------- +Boot-Image-Authenticity-1 | `CONFIG_FIT` | _Enable_ +Boot-Image-Authenticity-2 | `CONFIG_FIT_SIGNATURE` | _Enable_ +Boot-Image-Authenticity-3 | `CONFIG_RSA` | _Enable_ +Boot-Image-Authenticity-4 | `CONFIG_OF_CONTROL` | _Enable_ +Boot-Image-Authenticity-5 | `CONFIG_OF_SEPARATE` | _Enable_ +Boot-Image-Authenticity-6 | `CONFIG_DEFAULT_DEVICE_TREE` | _Enable_ + +<!-- end-section-config --> |