diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/imx/hab/habv4/encrypted_boot.txt | 43 | ||||
| -rw-r--r-- | doc/imx/hab/habv4/secure_boot.txt (renamed from doc/imx/README.mxc_hab) | 44 |
2 files changed, 43 insertions, 44 deletions
diff --git a/doc/imx/hab/habv4/encrypted_boot.txt b/doc/imx/hab/habv4/encrypted_boot.txt new file mode 100644 index 0000000000..c59d204d38 --- /dev/null +++ b/doc/imx/hab/habv4/encrypted_boot.txt @@ -0,0 +1,43 @@ +1. Setup U-Boot Image for Encrypted Boot +---------------------------------------- +An authenticated U-Boot image is used as starting point for +Encrypted Boot. The image is encrypted by i.MX Code Signing +Tool (CST). The CST replaces only the image data of +u-boot-dtb.imx with the encrypted data. The Initial Vector Table, +DCD, and Boot data, remains in plaintext. + +The image data is encrypted with a Encryption Key (DEK). +Therefore, this key is needed to decrypt the data during the +booting process. The DEK is protected by wrapping it in a Blob, +which needs to be appended to the U-Boot image and specified in +the CSF file. + +The DEK blob is generated by an authenticated U-Boot image with +the dek_blob cmd enabled. The image used for DEK blob generation +needs to have the following configurations enabled in Kconfig: + +CONFIG_SECURE_BOOT=y +CONFIG_CMD_DEKBLOB=y + +Note: The encrypted boot feature is only supported by HABv4 or +greater. + +The dek_blob command then can be used to generate the DEK blob of +a DEK previously loaded in memory. The command is used as follows: + +dek_blob <DEK address> <Output Address> <Key Size in Bits> +example: dek_blob 0x10800000 0x10801000 192 + +The resulting DEK blob then is used to construct the encrypted +U-Boot image. Note that the blob needs to be transferred back +to the host.Then the following commands are used to construct +the final image. + +cat u-boot-dtb.imx csf-u-boot.bin > u-boot-signed.imx +objcopy -I binary -O binary --pad-to <blob_dst> --gap-fill=0x00 \ + u-boot-signed.imx u-boot-signed-pad.bin +cat u-boot-signed-pad.imx DEK_blob.bin > u-boot-encrypted.imx + + NOTE: u-boot-signed.bin needs to be padded to the value + equivalent to the address in which the DEK blob is specified + in the CSF. diff --git a/doc/imx/README.mxc_hab b/doc/imx/hab/habv4/secure_boot.txt index a40ebf3e84..ae68dc8040 100644 --- a/doc/imx/README.mxc_hab +++ b/doc/imx/hab/habv4/secure_boot.txt @@ -98,47 +98,3 @@ cat u-boot-ivt.img csf-u-boot.bin > u-boot-signed.img These two signed binaries can be used on an i.MX in closed configuration when the according SRK Table Hash has been flashed. - -4. Setup U-Boot Image for Encrypted Boot ----------------------------------------- -An authenticated U-Boot image is used as starting point for -Encrypted Boot. The image is encrypted by i.MX Code Signing -Tool (CST). The CST replaces only the image data of -u-boot-dtb.imx with the encrypted data. The Initial Vector Table, -DCD, and Boot data, remains in plaintext. - -The image data is encrypted with a Encryption Key (DEK). -Therefore, this key is needed to decrypt the data during the -booting process. The DEK is protected by wrapping it in a Blob, -which needs to be appended to the U-Boot image and specified in -the CSF file. - -The DEK blob is generated by an authenticated U-Boot image with -the dek_blob cmd enabled. The image used for DEK blob generation -needs to have the following configurations enabled in Kconfig: - -CONFIG_SECURE_BOOT=y -CONFIG_CMD_DEKBLOB=y - -Note: The encrypted boot feature is only supported by HABv4 or -greater. - -The dek_blob command then can be used to generate the DEK blob of -a DEK previously loaded in memory. The command is used as follows: - -dek_blob <DEK address> <Output Address> <Key Size in Bits> -example: dek_blob 0x10800000 0x10801000 192 - -The resulting DEK blob then is used to construct the encrypted -U-Boot image. Note that the blob needs to be transferred back -to the host.Then the following commands are used to construct -the final image. - -cat u-boot-dtb.imx csf-u-boot.bin > u-boot-signed.imx -objcopy -I binary -O binary --pad-to <blob_dst> --gap-fill=0x00 \ - u-boot-signed.imx u-boot-signed-pad.bin -cat u-boot-signed-pad.imx DEK_blob.bin > u-boot-encrypted.imx - - NOTE: u-boot-signed.bin needs to be padded to the value - equivalent to the address in which the DEK blob is specified - in the CSF. |