OTFAD encryption

sathishkumar-rk — Fri, 02 Dec 2022 11:42:44 GMT

Hi Team,

I'm using i.MXRT1160_EVK board for my sample development work, where I want to enable the XiP encryption with OTFAD module.

My work plan is create the bootloader which will execute the slot-0 application. if any update image is available in slot-1 it has to swap the image between slots and execute content.

I'm using zephyr and mcuboot code for my project work. Can able to encrypt the mcuboot and slot-0 application and run it successfully!!

MCUBOOT

Slot-0 (application)

Slot-1 (upgradable image)

The problem i'm facing is when create encrypted upgraded image it was not able to decrypt correctly.

I assume OTFAD decryption is having flash location dependent. If i prepare image for slot-0 location and flash it directly to that location it's working.

In-case, if i do prepare image for slot-0 and flash it on slot-1 location then moving to slot-0 location and then execute it's getting failed. So, OTFAD will decrypt the content in the content remains same on same location else it will not decrypt properly?

Is that my assumption correct or am i missing something here?

commands used for creating encrypted binaries:

MCUboot:

iimage_enc.exe ifile=.\bootloader.signed.bin ofile=bootloader_enc.bin base_addr=0x30001000 kek=DAD4561645792590D5946289F043BECD otfad_arg=[0123456789abcdeffedcba9876543210,0020406001030507,0x30001000,0x0001F000],[383D4385A925D2EE734843817589F955,0020406001030508,0x30020000,0x002FE000]otfad_ctx_lock=0,0,0,0 is_boot_image=0 hw_eng=otfad

Slot-0:

image_enc.exe ifile=.\zephyr.signed.bin ofile=image1_enc.bin base_addr=0x30020000 kek=DAD4561645792590D5946289F043BECD otfad_arg="[383D4385A925D2EE734843817589F955,0020406001030508,0x30020000,0x02fe000]" is_boot_image=0 hw_eng=otfad

Slot-1:

image_enc.exe ifile=.\zephyr.signed.bin ofile=image2_enc.bin base_addr=0x30020000 kek=DAD4561645792590D5946289F043BECD otfad_arg="[383D4385A925D2EE734843817589F955,0020406001030508,0x30020000,0x02fe000]" is_boot_image=0 hw_eng=otfad

Let me if any further information is required.

Thanks,

Sathishkumar K

Re: OTFAD encryption

jay_heng — Sun, 04 Dec 2022 11:36:41 GMT

Have you tried to debug bootloader project to see what solt-1 image data is after swapping? Let's see it is swap issue or OTFAD decrypted issue.

Re: OTFAD encryption

sathishkumar-rk — Wed, 28 Dec 2022 07:10:04 GMT

Hi @jay_heng,

I have a observation on execution, if I used didn't swap the content between slots, then it able to execute.

Questions:
1. Is OTFAD has location dependency? because if do same content with different flash location the otfad keyblob is different.

2. While do swapping which content is getting swapped is encrypted text or plain text?

Thanks,

Sathishkumar K

Re: OTFAD encryption

sathishkumar-rk — Mon, 02 Jan 2023 05:21:45 GMT

Hi @jay_heng,

Is there any luck on my query regarding otfad encrytion?

Regards,

Sathishkumar K

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