Encryption of DFU_Application with NCS and MCUBoot

[HinnaX]

Hey,
I'm looking for a solution to encypt the DFU_Application.zip and that the nrf52840 MCU can encrpyt it at runtime.
Actually I've read that this not offical supported of nrf.
I've also read that there is a workaround to encrypt the image with the tool imgtool and the sign command with the arugment --encrpytion.

If I execute this command, the error occurs 
Error: Header padding was not requested and image does not start with zeros

Can please anybody help me, maybe with a small example how I can find a solution.

Best regards,
Hinnerk

[Amanda Hsieh]

Hi, 

Check out this post. 

Regards,
Amanda H.

[HinnaX]

Cool thanks, the encryption command is now working. What about decryption on the target. Which configuration is necessary for that?

[Amanda Hsieh]

Hi Hinnerk,

You can use SB_CONFIG_BOOT_ENCRYPTION to enable encryption support in MCUboot and set SB_CONFIG_BOOT_ENCRYPTION_KEY_FILE. The public key, derived from the specified private key file, is added to the image and later used on the device to derive the decryption key for the application image. This public key is automatically derived from the private key by imgtool, which is invoked by the build system when signing the image.

I will be out of the office for the next two weeks and will not be able to answer the case. If you need urgent support, please create a new support case.

Merry Christmas & Happy New Year!

Amanda H.