AM2434: Decryption of secure boot images in DDR

Manuel Philippin

Part Number: AM2434
Other Parts Discussed in Thread: LP-AM243

Tool/software:

Hello Sitara team,

This section (AM243x MCU+ SDK: Enabling Secure Boot) in the MCU+ SDK describes how decryption of the image can only be done in SRAM and the image size is limited to 256kB for the LP-AM243.

Does this also apply when using external DDR memory?

Do we have support for this in the SDK already?

Thanks and regards
Manuel

7 months ago

0 JJD 7 months ago

TI__Guru* 90745 points

The DDR needs to be initialized and trained before using it (this is done in SBL itself), so SBL decryption has to be done in internal memory.

Regards,

James

0 Manuel Philippin 7 months ago in reply to JJD

TI__Intellectual 1515 points

Hi James,

understood, that the SBL needs to be decrypted in internal memory.

But if the application image was encrypted, could this be decrypted on the DDR?

Regards
Manuel

0 JJD 7 months ago in reply to Manuel Philippin

TI__Guru* 90745 points

Yes, i believe this can be done. I think typically the application image is read from the non-volatile boot memory, decrypted, and then written to the DDR. But if the decrypted image was in DDR, i don't see any reason why you couldn't read in the decrypted binary from DDR, decrypt it, and write it back out.

Regards,

James

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AM2434: Decryption of secure boot images in DDR