• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 29 subscribers
  • Views 624 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

USB DFU Secure image

Christian Steiniche
Intellectual 565 points
Other Parts Discussed in Thread: TM4C1233D5PM

Hello


I am planning on using the Tivaware supplied boot loader to create a "secure" image upload to my device. For that purpose, I plan on using the BL_DECRYPT_FN_HOOK function which can be enabled in the boot loader configuration. I have two questions, which I cannot find answers to in the documentation:


1. Does the DFU interface specify any requirements to the sizes of the blocks transferred from the host to the device (e.g. is it a fixed block size, word aligned, etc...) ?


2. Does the boot loader support a method to abort the firmware upload in case the decryption of the image fails? I plan on using an authenticated encryption/decryption mode, with the authentication tag embedded in the image header. When the upload is completed and the tag does not match the expected tag, I would like to erase the image from flash (the image which has just been uploaded). Can this be done from within the decrypt call-back function, or does the boot loader support a better solution?


For the project I am currently using:
- TivaWare 2.1.0.12573
- Tm4c1233d5pm
- CCS v6
- TI v5.1.6 compiler

I appreciate any help you can provide.

Best regards
Christian

  • 0
    TI__Mastermind 22560 points
    Hello Christian,

    The DFU device information structure can handle flash page sizes in the range 1KB to 32KB. The configuration option "FLASH_PAGE_SIZE" has to be set to the correct page size. If a value greater than 32KB is set then it is defaulted to 32KB. Refer the file "<TivaWare_Install_Directory>/boot_loader/bl_usb.c" for details of this implementaion.

    The bootloader has another hook function "BL_END_FN_HOOK" which is called when the firmware download is completed. This seems to be a more appropriate function to do the clean-up.

    Thanks,
    Sai
  • 0 in reply to Sai Reddy
    Intellectual 565 points
    Hello Sai,

    I did not know that the upload block size would be defined by the flash page size - thanks for clarifying. Also, the BL_END_FN_HOOK sounds like a good solution.

    Thansk for your help!

    Br
    Christian