I have LM3S9B96. I want to disable any external debuggers such as JTAG/SWD and be sure that there are no way to read flash content using built-in bootloader and LM Flash Programmer. As I understand Boot Configuration (BOOTCFG) Register allow me to disable any external debugger, but i can't understand will it be possible to use buil-in rom bootloader to erase flash and download firmware. And the most important question will it be possible to read flash in this case. My task requires some level of security when it is not possible to read flash, but it is possible to erase flash and download new firmware. What is the best way to acchive my goal.
The short answer is yes, you can do what you are discussing (make flash write-execute only, disable JTAG access to the processor). There are some high-level notes on these topics in this AppNote. And, of course, the processor datasheet also contains more information in the 'Internal Memory' chapter.
Vladim-ir security when it is not possible to read flash,
Suggestions offered make it more difficult - but in no way, "not possible" to secure your code w/in flash. Understand that this is not any weakness of TI and/or Stellaris - all makers of such class/price MCUs offer roughly the same level of "code readout protection." Realize that determined "code seeker" will have access to powerful tools & methods - substantial experience in "security bypass" - and great access to an abundance of specialized code-extraction resources. (i.e. "de-caping" the IC and/or X-Ray of the memory array - and beyond...)
You can place some obstructions in invader's path - but folly to consider your code, "secure." Issue was covered in recent forum post should you seek further detail...
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