Here’s a thought experiment: take a look at the Tillitis Key: https://tillitis.se It’s a security dongle that can execute arbitrary programs. It’s hardware is actually a RISC-V core implemented on top of an FPGA, with some firmware on top to load the user programs.

Now the firmware is a kind of software, so patent should not apply, right? Heck one could even argue that the configuration of the FPGA should not count either, only the FPGA itself may count. There’s a problem though: the keys are locked.

They kinda have to be to deliver their security promises, and prevent the secret key in the device from leaking, either by accident or by adversarial extraction. But then what do I have? A hardened piece of… hardware actually. And all the patents that didn’t apply "because software", now do.

Or maybe they do not, I’m not a lawyer. I just wanted to highlight how fuzzy the frontier could be.