[Brinworld] Car's data recorder convicts driver

[Tim May]

On Wednesday, June 18, 2003, at 06:15  PM, Thomas Shaddack wrote:

> On Wed, 18 Jun 2003, jburnes wrote:
>> Why go to all that trouble.  Just take it out of circuit.  Cut the
>> printed circuit
>> board leads and disable it or if its in an inaccessible black box, cut
>> the
>> leads to the box.
>>
>> Easy enough.
>
> Works very nicely. :)
>
> Problem: leaves evidence, and takes time. The main advantage of 
> electric
> shock is that the fried chip looks for the naked eye exactly the same 
> way
> as a non-fried chip. The only difference could be found with a scanning
> electron microscope on the chip itself, which is something nobody is
> likely to bother with. Especially in harsh environments (cars classify)
> chips tend to die, so its death could look as natural enough to not be
> suspicious.
>
> If I am wrong, please tell me where and why. :)
>

The point being that sensor data from outside the box does NOT get 
written to either flash or disk drive storage directly. It is collected 
from many places and fed through the assortment of microprocessors.

High voltages are clamped in the usual ways, with Schottky diodes 
protecting the inputs, etc. Even if signals massively outside the specs 
got into the boxes, it would be the processors which got fried, not the 
storage devices. This was my point about how "sparky things" would not 
overwrite data.

It takes logic to correctly write to storage.

The processors and peripheral logic _might_ be zapped, but the storage 
chips would almost certainly not have been erroneously 
overwritten...just a matter of disconnecting them and reading them in 
another system, something most forensic or recovery labs probably have 
many jigs set up for.


--Tim May