AM2634: Example Project For TI Delivered HSMRt

Hello Kier,

To get access to this please review and follow the guidance of this FAQ: https://e2e.ti.com/support/microcontrollers/arm-based-microcontrollers-group/arm-based-microcontrollers/f/arm-based-microcontrollers-forum/1136004/faq-what-are-the-ti-deliverables-for-security-in-mcu-devices/4215529#4215529

Best Regards,

Ralph Jacobi

Hello Ralph,

Apologies. I didn't make this clear but I already have what you call the "care package" in your link, TIFS etc. With that in mind, can you try to answer the questions please.

In short, in TIFS (or anywhere else) there is no example project that can use the default HSMRt. i.e. That which that can be used with HS-FS device.

Hi Kier,

Kier said:

Q1 : Is the TI delivered HSMRt the image contained in the file hsmRtImg.h in the MCU_SDK?

YES. Check at source/drivers/hsmclient/soc/am263x/hsmRtImg.h

Kier said:

Q2: If so, I could not find any example projects which use this default HSMRt. The only examples I can find are in TIFS. However the TIFS documentation says "Support Device Type: HS-SE" for all the examples. So at the moment, I cannot find a project example that can be used on an HS-FS device with the default HSMRt. Does one exist please or do I have to create one from scratch?

Check the Example available in examples/drivers/hsmclient which demonstrates all the hsm_services in a single example.

Best Regards,
Aakash

Aakash Kedia said:

Check the Example available in examples/drivers/hsmclient

Thank you but my point of confusion is that the example you mention (hsm_services_am263x-cc_r5fss0-0_nortos_ti-arm-clang) doesn't actually use hsmRtImg.h. If I comment out #define HSMRT_IMG, the example program still builds.

Put another way, how does the HSM program (in hsmRtImg.h) get loaded into RAM such that the HSM can service a request from the R5F client?

Sorry about the dumb questions. I'm having trouble visualising how all this hangs together.

Hi Aakash,

Thanks for the info.

The document is for Secure Boot which is not active in a HS-FS device. Also, at the top of the document it says "This document only accounts for boot flow in HS-SE devices". Therefore this is not applicable for HS-FS devices.

EDIT: Having said that I now see that the boot flow diagram in your link implies that the HSM is embedded in the SBL. This is further clarified by this link:

https://software-dl.ti.com/mcu-plus-sdk/esd/AM263X/latest/exports/docs/api_guide_am263x/SECURITY_PAGE.html#autotoc_md852

It says "The firmware is provided in an encrypted form at source/drivers/hsmclient/soc/hsmRtImg.h. The function Bootloader_socLoadHsmRtFw sends a message to ROM and ROM loads the HSM firmware."

So now I get it: The SBL asks HSM ROM to load the HSMRt from the SBL payload.

Q3: Please confirm that when I use an SBL (incorporating hsmRtImg.h) on an HS-FS device, that it will authenticate and run?

Q4: The above implies that any boot mode which does not involve an SBL (e.g. DevBoot) cannot load code into the HSM, is that correct please?

Thank you.

That's great Aakash. I think I am nearly there so please bear with me.

So my understanding is that I can proceed as follows:

    - Launch a debug session (DevBoot) on an HS-FS device.

    - Load an SBL (which has embedded TI HSMRt) using the 'load_sbl.js' script.

    - Load the example R5F program (hsm_services) and run. APIs like HsmClient_getVersion() should work.

Have I got that right please?