How to robustly protect a STM32F4xx against code extraction...

[jeanpierre]

Posted on November 14, 2014 at 00:18

Hello ST gurus!

Our company is seeking to protect its IP as much as possible from code extraction before products are shipped. We understand the STM32F4xx has protective features to prevent code extraction via JTAG and flash reading / writing in certain modes, but previous attempts have bricked a few boards and we would like to obtain the proper sequence of step to lock the device as securely as possible when product is factory-provisioned, and how to unlock it in our firmware upgrade process. I could not find an appnote or a code fragment that reveals how to properly do it.  Is there a code sample that someone can share that illustrates the proper procedure? Many thanks!!    Jean-Pierre #code-protection #locking #down-at-the-first-hurdle

[Tesla DeLorean]

Posted on November 14, 2014 at 18:15

Intriguing comment!  Should I be of impression that full protection of our code is impossible on this platform?

Well it depends on who your adversary is, the skill set they have and the equipment at their disposal. Your question  suggests you're fumbling with the operation of your front door locks, whilst the people you seek to protect against are skilled at picking locks, breaking windows, and kicking in back doors. I don't think the STM32 front door is any less secure than others. It will keep out the casual from poking at your design, but IC's and the software on them, are vulnerable to all kinds of attack, so what does ''robust'' mean? You need to be smarter and more resourceful than those you expect to protect against, this will require a lot of hands-on experience you're not going to learn from people in an open forum, or who have invested a lot of engineering resources to secure.

[jeanpierre]

Posted on November 14, 2014 at 23:27

Excellent!  Many thanks for everyone who participated!