doc: mxc_hab: Update i.MX HAB documentation
The README.mxc_hab is outdated and need improvements, add the following modifications: - Reorganize document and remove duplicate content - Add CST download link - Update CST package name - Align command lines with CST v2.3.3 - Update U-Boot binary name - Remove CSF padding since is not documented in AN4581 Signed-off-by: Breno Lima <breno.lima@nxp.com>
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Breno Lima
Stefano Babic
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6d7403bf72
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@ -11,14 +11,22 @@ In addition, the U-Boot image to be programmed into the
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boot media needs to be properly constructed, i.e. it must contain a
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proper Command Sequence File (CSF).
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The Initial Vector Table contains a pointer to the CSF. Please see
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doc/README.imximage for how to prepare u-boot.imx.
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The CSF itself is generated by the i.MX High Assurance Boot Reference
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Code Signing Tool.
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https://www.nxp.com/webapp/sps/download/license.jsp?colCode=IMX_CST_TOOL
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The CSF itself is being generated by Freescale HAB tools.
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More information about the CSF and HAB can be found in the AN4581.
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https://www.nxp.com/docs/en/application-note/AN4581.pdf
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mkimage will output additional information about "HAB Blocks"
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which can be used in the Freescale tooling to authenticate U-Boot
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(entries in the CSF file).
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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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2. Secure Boot on non-SPL targets
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---------------------------------
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On non-SPL targets a singe U-Boot binary is generated, mkimage will
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output additional information about "HAB Blocks" which can be used
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in the CST to authenticate the U-Boot image (entries in the CSF file).
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Image Type: Freescale IMX Boot Image
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Image Ver: 2 (i.MX53/6 compatible)
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@ -34,46 +42,35 @@ HAB Blocks: 177ff400 00000000 0004dc00
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--------------------------- (3)
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(1) Size of area in file u-boot.imx to sign
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(1) Size of area in file u-boot-dtb.imx to sign
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This area should include the IVT, the Boot Data the DCD
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and U-Boot itself.
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(2) Start of area in u-boot.imx to sign
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(2) Start of area in u-boot-dtb.imx to sign
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(3) Start of area in RAM to authenticate
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CONFIG_SECURE_BOOT currently enables only an additional command
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'hab_status' in U-Boot to retrieve the HAB status and events. This
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can be useful while developing and testing HAB.
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Commands to generate a signed U-Boot using Freescale HAB tools:
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cst --o U-Boot_CSF.bin < U-Boot.CSF
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objcopy -I binary -O binary --pad-to 0x2000 --gap-fill=0x00 \
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U-Boot_CSF.bin U-Boot_CSF_pad.bin
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cat u-boot.imx U-Boot_CSF_pad.bin > u-boot-signed.imx
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Commands to generate a signed U-Boot using i.MX HAB CST tool:
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# Compile CSF and create signature
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cst --o csf-u-boot.bin --i command_sequence_uboot.csf
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# Append compiled CSF to Binary
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cat u-boot-dtb.imx csf-u-boot.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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2. Using Secure Boot on i.MX6 machines with SPL support
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-------------------------------------------------------
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3. Secure Boot on SPL targets
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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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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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i.MX HAB 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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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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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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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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@ -92,23 +89,22 @@ Example Output of the u-boot-ivt.img (firmware_ivt) creation:
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Entry Point: 00000000
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HAB Blocks: 0x177fffc0 0x0000 0x00054020
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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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cst --o csf-u-boot.bin --i command_sequence_uboot.csf
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cst --o csf-SPL.bin --i 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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These two signed binaries can be used on an i.MX6 in closed
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These two signed binaries can be used on an i.MX in closed
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configuration when the according SRK Table Hash has been flashed.
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3. Setup U-Boot Image for Encrypted Boot
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-----------------------------------------
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4. 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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u-boot.imx with the encrypted data. The Initial Vector Table,
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Encrypted Boot. The image is encrypted by i.MX Code Signing
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Tool (CST). The CST replaces only the image data of
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u-boot-dtb.imx with the encrypted data. The Initial Vector Table,
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DCD, and Boot data, remains in plaintext.
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The image data is encrypted with a Encryption Key (DEK).
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@ -138,9 +134,7 @@ U-Boot image. Note that the blob needs to be transferred back
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to the host.Then the following commands are used to construct
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the final image.
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objcopy -I binary -O binary --pad-to 0x2000 --gap-fill=0x00 \
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U-Boot_CSF.bin U-Boot_CSF_pad.bin
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cat u-boot.imx U-Boot_CSF_pad.bin > u-boot-signed.imx
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cat u-boot-dtb.imx csf-u-boot.bin > u-boot-signed.imx
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objcopy -I binary -O binary --pad-to <blob_dst> --gap-fill=0x00 \
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u-boot-signed.imx u-boot-signed-pad.bin
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cat u-boot-signed-pad.imx DEK_blob.bin > u-boot-encrypted.imx
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