Setting up PGP

[grarpamp]

> usbs have microchips that accept code updates

USB "converters" should be considered suspect.

Plugging BadUSB's, BadHDD, CPU's, Flash, or any
other chipped / smart device or port with firmware, microcode,
chips etc between systems has potential to infect / attack them.

Assuming some random magical usb converter
cable sets do pass raw rs-232 between them
(ie: can cut/splice to a rs-232 port / modem / teletype)
users often probably fuck up and cross infect
usb during the n-th insertion setup session.

Various "air gap", all adaptable to 'cat hugefile > /device'...

QR code
OCR scanning
Sound
Light
RF
Keyboard bots
Monitor display output to camera capture input,
a digital stream of bits thrown onscreen as fast
as the two can sync.

Simple RS-232 protocols, ECC codes, etc.

All assuming endpoint chipsets don't attack over the gap / wire.
Keep simple enough to see, log, debug, verify, filter, audit... like ASCII.

USB, optical disk, tape, hdd... often have media
based firmware update mechanisms, exploits,
special sectors, bootcode, emulation, etc.

> scrabble tiles

As received from the store... exhibit a non-random
character frequency count, should not be used without
adjustment down to 1:1.