barcode 2 eye
steps
[ ] byte string -> barcode
[ ] generate string for signing
{
}
[ ] UTF8 -> Byte string -> 2D (QR) code ->
[ ] [with camera] barcode -> byte string
important
https://pypi.org/project/pyzbar/
https://crates.io/crates/rxing
https://crates.io/crates/barcoders
https://crates.io/crates/dbr