topic Re: How to unsecure the mcu using backdoor key access in S32K

How to unsecure the mcu using backdoor key access

jimfung — Wed, 19 Apr 2017 12:37:26 GMT

When the mcu was secured, then how to unsecure the mcu using backdoor key access？How to know the contents of the 8-bytes backdoor key value stored in the Flash?

Re: How to unsecure the mcu using backdoor key access

danielmartynek — Thu, 20 Apr 2017 21:10:01 GMT

Hi,

When the MCU is secure, the debugger can’t read registers, it has no access to the MCU except for mass erase which will unlock the MCU. The MCU can be unsecured by the code itself using Verify Backdoor Access Key command.

Please refer to the example code. The MCU is secured in the start-up code (startup_S32K144.S), see Flash Configuration, backdoor comparison key: 0xAAAAAAAAAAAAAAAA.

Power-on reset is needed to run the MCU stand alone. Red LED on the EVB indicates the MCU is secure.

Verify backdoor key command, which will unlock the MCU and which is executed from RAM, is delayed with a delay loop. After that the MCU will be unsecured and the LED will turn BLUE.

Regards,

Daniel

Re: How to unsecure the mcu using backdoor key access

jimfung — Fri, 21 Apr 2017 01:04:06 GMT

Hi Daniel,

Thanks for help!

Best regards,

Jim

Re: How to unsecure the mcu using backdoor key access

hajianik — Wed, 10 May 2017 15:57:26 GMT

Hi Daniel,

I'm having the same issue. I imported your project and try to build it however I get the following errors:

./src/main.o: In function `main':

C:\ECLIPSE_WS\S32K144_backdoor_key_access_S32DS1.3\Debug_RAM/../src/main.c:166: undefined reference to `__MY_RAM_SIZE'

C:\ECLIPSE_WS\S32K144_backdoor_key_access_S32DS1.3\Debug_RAM/../src/main.c:166: undefined reference to `__MY_RAM_ADR'

C:\ECLIPSE_WS\S32K144_backdoor_key_access_S32DS1.3\Debug_RAM/../src/main.c:166: undefined reference to `__MY_RAM_ROM_ADR'

collect2.exe: error: ld returned 1 exit status

make: *** [S32K144_backdoor_key_access_S32DS1.3.elf] Error 1

I thought may be they are in the linker file, but I just can't find them.

Any ideas?

Thanks,

Koorosh Hajiani