[everlastingfan]

Well there is when you design signals that play on the physical properties of the silicon and the silicon design is known, think Rowhammer. The next level of this is making permanent modifications to the silicon, e.g. using focused RF signals to change the properties of individual transistors.

Relying on security through obscurity is bad, but you need some obscurity.

Passwords and keyfiles are ultimately a form of security through obscurity.