Fun fact: many desktop printers can hit 3kbps in V40L QR codes (biggest + lowest ECC). (Estimated at approx 10ppm by 20KiB per code.) For the security conscio

Fun fact: many desktop printers can hit 3kbps in V40L QR codes (biggest + lowest ECC). (Estimated at approx 10ppm by 20KiB per code.) For the security conscious on a budget, printing QR codes to scan to a networked machine can be a way to get information off an otherwise air-gapped machine, with easy introspection and auditing. (This came up in the context of offline signing of Bitcoin transactions with a "warm" wallet -- digital, but airgapped from the "hot" wallets.)