Em 11/2/2010 12:01, Alan B. Pearce escreveu:
>>> You mean you haven't checked out how to protect the bootloader area?
>>>       =

>> How could I protect it against erase? All PICs can be erased,
>> can't they?
>>     =

> Yes they can - if you can get at the ICSP connection.
>
>   =

>> And if they can't, the attacker could replace the PIC for a
>> new one, and put the spoofed bootloader into that new PIC.
>>     =

> But you are missing the point. By making the ICSP connection available, b=
y =

> bringing out the PGM connection, then anybody can do anything to the code=
 in =

> the devices you are producing.
>   =


No way! If the part is code-protected, the only thing one can do is to
erase the part. After erasing then he can do whatever he wants (program,
debug, read, etc.), but the original firmware/bootloader will  not be
there anymore.

> By having a bootloader it is possible to set most chips up so that the =

> bootloader is protected against erasure, and it ensures that whatever doe=
s =

> get downloaded is from a controlled source. The bootloader can only be =

> erased if the PGM connection is brought out to the outside world.
>   =


Even if you cut the ICSP pins close to the package, somebody could
scratch the plastic to solder some wires to them. He could even unsolder
the chip and buy a new blank one.

It is not possible to ensure that nobody will damage the equipment or
erase the firmware. What you should be worried of is to protect the
intellectual property inside it. If your customer damage the equipment,
lucky you, he will need to buy a new one.


Regards,

Isaac
__________________________________________________
Fa=E7a liga=E7=F5es para outros computadores com o novo Yahoo! Messenger =

http://br.beta.messenger.yahoo.com/ =


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