Changes between Version 34 and Version 35 of venice/secure_boot

Timestamp:

06/18/2024 08:52:50 PM (3 months ago)

Author:

Tim Harvey

Comment:

added additional info about SRK HASH

venice/secure_boot

@@ -36 +36 @@
 The HABv4 secure boot feature uses digital signatures to prevent unauthorized code execution during the device boot sequence. This authentication is based on public key cryptography using RSA where the firmware image data is signed offline using a private key and the resulting signed image data is verified on the processor using the corresponding public key hash value programmed into the SoC fuses for establishing the root of trust.
 
+The Super Root Key (SRK) is an RSA key pair which forms the start of the boot-time authentication chain. The hash of the SRK public key is embedded in the processor using OTP hardware. The SRK private key is held by the CA. The SRK in this document (unless noted) refers to the public key only.
+
+The authentication begins with establishing a root of trust with the SRK. HAB does this by computing a cryptographic hash of the SRK table and comparing the result with a pre-computed hash that is provisioned in OTP fuses.
+
+The SRK_HASH fuses for the IMX6/IMX7/IMX8 are defined by a bank and a word:
+ - SRK_HASH[31:00] bank 6 word 0
+ - SRK_HASH[63:32] bank 6 word 1
+ - SRK_HASH[95:64] bank 6 word 2
+ - SRK_HASH[127:96] bank 6 word 3
+ - SRK_HASH[159:128] bank 7 word 0
+ - SRK_HASH]191:160] bank 7 word 1
+ - SRK_HASH[223:192] bank 7 word 2
+ - SRK_HASH[255:224] bank 7 word 3
+
 See also:
- - https://elixir.bootlin.com/u-boot/latest/source/doc/imx/habv4/guides/mx8m_spl_secure_boot.txt
- - https://elixir.bootlin.com/u-boot/latest/source/doc/imx/habv4/introduction_habv4.txt
- - NXP AN4581 - i.MX Secure Boot on HABv4 Supported Devices
+ - [https://elixir.bootlin.com/u-boot/latest/source/doc/imx/habv4/guides/mx8m_spl_secure_boot.txt U-Boot mx8m_spl_secure_boot.txt]
+ - [https://elixir.bootlin.com/u-boot/latest/source/doc/imx/habv4/introduction_habv4.txt U-Boot introduction_habv4.txt]
+ - [https://community.nxp.com/pwmxy87654/attachments/pwmxy87654/imx-processors/160465/1/AN12056.pdf AN12056 Encrypted Boot on HABv4 and CAAM Enabled Devices]
+ - [https://community.nxp.com/pwmxy87654/attachments/pwmxy87654/imx-processors/112842/1/AN4581.pdf AN4581 Secure Boot on i.MX50, i.MX53, and i.MX 6 Series using HABv4]
+
 
 Terminology: