If you want to have a little fun then writing a python script to convert a file to beeps and recover it from beeps is quite doable.
It also teaches you just how insane the speeds we have today are.
It also teaches you just how insane the speeds we have today are.
I wanted to store a gpg key offline by engraving it in metal. A reasonably sized one would taken six of the largest 177x177 plates to record.
The best solution I came up with was to use metallic punched tape of some description.
The practical limit was 3KiB for the qr code and there was some metadata in the key I didn't want to lose. I can't remember if it was the private or public key that was giving me the most trouble. But the idea of just having something to point your phone at on a wall and read a signed message from me wasn't practical.
I'm experimenting for fun on this side: https://github.com/dtonon/papiro
> 0–9, A–Z (upper-case only), space, $, %, *, +, -, ., /, :
and so we miss the lowercase [a-z]. Therefore we need to use the 2953 bytes binary option.
Points of difference: I was using a leading metadata frame with filename and total number of frames etc, and the receiving device were ACK'ing frame decodes with its own QR codes. Still, wow.