Read Out Protect - Only a section?

[mwp]

Posted on January 31, 2013 at 13:48

Hi all,

Is it possible to read out protect only one specific area of flash?

I want to use a bootloader that can program both encrypted and un-encrypted programs.

I need to protect the bootloader from being read so un-encrypted (non-trusted) programs cannot access the encryption method/keys in the bootloader.

Is this possible somehow?

Thanks in advance!

[mwp]

Posted on January 31, 2013 at 14:53

Ok... so obviously ROP is of no use here as non-trusted firmware can still access the bootloader even if ROP could only be enabled for that section of flash.

So... is there any other way of doing what im after?

[Tesla DeLorean]

Posted on January 31, 2013 at 15:52

Code running in FLASH, and copied out of flash into RAM, can read the entire memory space.

You could copy data to RAM from a ROP'd device and then reset with BOOTx pins set to execute from RAM, such code would not be able to read the ROM or FLASH.

[mwp]

Posted on January 31, 2013 at 16:04

Hardware is in production, so i guess it cant be done.

Thanks.