Creating a safe DFU bootloader

[Dave_couling]

I am trying to figure out a way to secure my DFU (via BLE) such that someone cannot sniff the and copy my hex code (and decompile). I cannot use Pairing or Bonding as that doesn't work for our usecase. So I need to a way to encrypt my hex image in a way that it can be decrypted in the bootloader upon reciept. As far as I can see there is no AES decryption available, so the only option would be inventing my own data encryption/decryption. However I wanted to post here just in case I am wrong in my conclusion.

[cocoa]

Hi,

see this post and this .

-c

[Hung Bui]

@Dave: Did the reply from cocoa answer your question? If it does please accept it and we can close the case :)

[Dave_couling]

Unfortunately, the links provided have not helped me determine a solution.

[Hung Bui]

@Dave: I believe this answer from Clem Taylor answerred your question. If you use CFB mode, you should be able to use the same ECB encryption (with no decryption) to do AES. You can have a look here.