STM32U5 RDP regression without JTAG/SWD

[ELuca.2]

Hello ST Community,

There was a thread by Aurelien about this topic, but I did not understand the answer. So let me rephrase the question with my own words.

I have a STM32U5 based device with high security settings (TZEN=1, RDP=2). Is there any other means to regress to TZEN=0, RDP=0 than OEM2KEY provisioning and JTAG/SWD communication? By software?

Regards.

[Diane POMABIA · Accepted solution]

Hello @ELuca.2 

It's not possible to regress RDP without JTAG. Because to define your OEM2KEY, you have to use external Debug and after activate your RDP= 2 , you will  lost your degug.The only access you will be provided by Cubeprogrammer to get your OEM2KEY.

Regards

Diane

[ELuca.2]

Hello Diane,

I was thinking about directly writing the OEM2KEY into the DBGMCU_DBG_AUTH_HOST register, from a secure and privileged piece of code in the firmware, not using CubeProgrammer. You confirm it is not possible?

[Diane POMABIA · Accepted solution]

Hello Eric, 
yes, it's not possible .
Regards
Diane