[Cryptech Tech] Alpha board BOM and PCB design requirements

[Jakob Schlyter]

On 14 mar 2015, at 21:02, Павел Шатов <meisterpaul1 at yandex.ru> wrote:

> We should estimate average current consumption of the tamper detection circuit. We need to define a list of sensors that we want, find corresponding components and download their datasheets. Then write down current consumption of all the sensors. This will clearly tell us what kind of battery we need.

Yes! Temperature and gyro are the sensors in my mind, but there may be others as well.

> I once again suggest to use something like PIC16/18 from Microchip. These MCUs are much simpler, they are 8-bit, not 16-bit. They have an order of magnitude less power consumption then MSP430. Another nice feature is that they have high-voltage programming mode. You can buy or make your own high-voltage programmer (and have hand-made JDM and PicKit3 from Microchip). This high-voltage programmer can be used to completely disable low-voltage in-system programming mode, write-protect program memory and disable readback. You will physically not be able to change anything in this MCU without attaching a high-voltage programmer. I believe this is the right way to make tamper detection circuit.

The programming and power properties you describe sounds interesting and something we should consider.

As Warren wrote, just cutting the power to the memory might not be enough if your attack has enough resources to analyze the memory after a power cut. Given that risk, I'd recommend that we do active erase.


	jakob