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@@ -1,4 +1,5 @@
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-High Assurance Boot (HAB) for i.MX6 CPUs
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+1. High Assurance Boot (HAB) for i.MX CPUs
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+------------------------------------------
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To enable the authenticated or encrypted boot mode of U-Boot, it is
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required to set the proper configuration for the target board. This
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@@ -52,8 +53,58 @@ cat u-boot.imx U-Boot_CSF_pad.bin > u-boot-signed.imx
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NOTE: U-Boot_CSF.bin needs to be padded to the value specified in
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the imximage.cfg file.
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-Setup U-Boot Image for Encrypted Boot
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--------------------------------------
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+
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+2. Using Secure Boot on i.MX6 machines with SPL support
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+-------------------------------------------------------
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+
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+This version of U-Boot is able to build a signable version of the SPL
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+as well as a signable version of the U-Boot image. The signature can
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+be verified through High Assurance Boot (HAB).
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+
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+CONFIG_SECURE_BOOT is needed to build those two binaries.
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+After building, you need to create a command sequence file and use
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+Freescales Code Signing Tool to sign both binaries. After creation,
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+the mkimage tool outputs the required information about the HAB Blocks
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+parameter for the CSF. During the build, the information is preserved
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+in log files named as the binaries. (SPL.log and u-boot-ivt.log).
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+
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+More information about the CSF and HAB can be found in the AN4581.
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+https://cache.freescale.com/files/32bit/doc/app_note/AN4581.pdf
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+
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+We don't want to explain how to create a PKI tree or SRK table as
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+this is well explained in the Application Note.
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+
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+Example Output of the SPL (imximage) creation:
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+ Image Type: Freescale IMX Boot Image
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+ Image Ver: 2 (i.MX53/6/7 compatible)
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+ Mode: DCD
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+ Data Size: 61440 Bytes = 60.00 kB = 0.06 MB
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+ Load Address: 00907420
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+ Entry Point: 00908000
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+ HAB Blocks: 00907400 00000000 0000cc00
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+
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+Example Output of the u-boot-ivt.img (firmware_ivt) creation:
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+ Image Name: U-Boot 2016.11-rc1-31589-g2a4411
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+ Created: Sat Nov 5 21:53:28 2016
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+ Image Type: ARM U-Boot Firmware with HABv4 IVT (uncompressed)
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+ Data Size: 352192 Bytes = 343.94 kB = 0.34 MB
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+ Load Address: 17800000
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+ Entry Point: 00000000
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+ HAB Blocks: 0x177fffc0 0x0000 0x00054020
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+
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+The CST (Code Signing Tool) can be downloaded from NXP.
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+# Compile CSF and create signature
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+./cst --o csf-u-boot.bin < command_sequence_uboot.csf
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+./cst --o csf-SPL.bin < command_sequence_spl.csf
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+# Append compiled CSF to Binary
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+cat SPL csf-SPL.bin > SPL-signed
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+cat u-boot-ivt.img csf-u-boot.bin > u-boot-signed.img
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+
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+These two signed binaries can be used on an i.MX6 in closed
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+configuration when the according SRK Table Hash has been flashed.
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+
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+3. Setup U-Boot Image for Encrypted Boot
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+-----------------------------------------
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An authenticated U-Boot image is used as starting point for
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Encrypted Boot. The image is encrypted by Freescale's Code
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Signing Tool (CST). The CST replaces only the image data of
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