I was a bit confused what use an FFT had here since I was only familiar with the Fourier transform in the _forward_ direction (compute the component frequencies of a signal given samples). But this uses the _inverse_ Fourier transform, which effectively lets you take samples of a signal given its component frequencies. Here, those component frequencies are generated by mathematical functions developed (by other researchers) to model ocean waves, which are explained in https://github.com/2Retr0/GodotOceanWaves#ocean-wave-spectra.
I love ET. Some discussion here of its advantages over mosh: https://news.ycombinator.com/item?id=21640200. Beware that ET does phone home: depending on how it's packaged for your system, telemetry is enabled by default in /etc/et.cfg.
Duo was one of the last things keeping me from switching to Google-free AOSP, and I toyed with a similar idea while trying to reverse-engineer a free software replacement. Instead, I ended up writing a small tool that allows you to use any old HOTP authenticator with Duo. I use FreeOTP+ on my phone, but you could just as easily stick that HOTP secret in a script or onto a Yubikey. You might find it useful if you're working your way up to 100% Stallman status: https://github.com/evan-goode/duolibre.
By the way, I gotta say this project is pretty hilarious, and you're a true baller for trying to sell this to people.
