[Cryptech Tech] Tamper detection

[Fredrik Thulin]

On tisdag 19 juli 2016 kl. 10:04:31 CEST Jakob Schlyter wrote:
> Richard Lamb has offered to help out with tamper detection and the plan
> we have come up with is that he will create a small tamper daughterboard
> that connects to the 10-pin tamper GPIO on the alpha board, along with
> some updated code for the AVR. Once we have more experience with the
> tamper circuits, we can fold the components into the main board.
> 
> For this to be really usable, we need a battery on the alpha board. This
> can be implemented by adding a battery holder to the next rev
> and/or adding an external battery to rev03. Rick suggested that we might
> want to use a larger battery in combination with a supercapacitor so the
> battery can be replaced without loosing the MKM.

The next revision (rev04) ought to fix the current leakage from the VBAT to 
the 3V3 rail, but after some more thinking I think maybe the tamper 
daughterboard can have the battery connector/super-cap. That way the 
daughterboard will be usable with the current rev03's too.

Stated differently, the tamper daughterboard could feed the VBAT on the Alpha 
instead of being fed by the VBAT on the Alpha.

Any downsides to that?

/Fredrik