[onerng talk] design decision questions

Gerd v. Egidy lists at egidy.de
Mon Dec 29 00:07:50 GMT 2014

> That tells us that the thing is less likely to be tampered with at a
> simple level.  That's because "indistinguishable from random" is
> actually very easy to fake, where as obscure biases are somewhat harder
> to fake.

you mean measuring the specific bias of your device when you bought & verified 
it and then later on during use checking for that specific bias as something 
like an id of your device?

I don't think that will work particularly well with the hardware design of 
onerng: it is using two separate transistors. When there is a small 
temperature gradient between them, the characteristics of them will change 
differently. Also they slowly drift with age and humidity.

To protect the device against hardware tampering or replacement against a fake 
device I'd suggest different methods like digitally signing and encrypting the 
usb datastream, combined with activating the readout protection and filling the 
shield with epoxy.

Kind regards,


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