[Avila] How I can protect my program from not authorized reading via JTAG?

[David Acker]

Tim Harvey wrote:
> Nikita,
> 
> I've often thought about this as well.  There really isn't any way to do this.  For starters, Gateworks programs the firmware on their boards using the JTAG connector, so the connector will always be loaded on the board.  If they were to move to pads/testpoints vs a physical connector this would make it more difficult for someone not familiar with the board to read but certainly not for the resourceful.  That said, removing the connector and/or possibly resistors that may link that connector to the JTAG chain would make it more difficult but not for the resourceful.
> 
> In my opinion, because you will never be able to keep someone from reading the JTAG chain you would have to do something to encrypt/protect the info from the flash they would be able to read which may require quite a bit of bootloader/kernel modification.
> 
> Of course, regardless of the time/effort/$$ you put into protecting a system if someone really wants to get into it and has the know-how they probably will (ie, XBOX, XBOX-360, DVD CSS encryption, DVD-HD and Blueray - these have all been hacked)
> 
> I wonder if there is a way to 'blow' the JTAG circuits on some/all of the devices to make it impossible to read via JTAG (and impossible to re-program a bricked board).
> 
> Tim

I used to use TI's MSP430 and http://www.softbaugh.com sold a JTAGer 
that would do exactly that for use in manufacturing.  Put the software 
on it and blow the fuse.
-Ack