Also after writing the encrypted message onto the floppy disk, eject it and then flip the write protect tab on the floppy. So that you only read encrypted.asc and sha256sum.txt from the floppy on your transmission work station when sending the file.

In general you can improve this protocol by having 2 air-gaped computers, that share your private key. One for decrypting messages, the other for encrypting messages. That way information never flows back and forth between your air-gap stations and the transmission computer.


READ ONLY Floppy 1 computer 1
[TRANSMISSION STATION] <-------------- [ENCRYPT STATION]

computer 2
Floppy 2 READ ONLY
[TRANSMISSION STATION] --------------> [DECRYPT STATION]


The transmission station has the tor mail server (postfix) with tor and endmail. The Encrypt and Decrypt station are separate computers that share your private key for pgp (not necessary if you're not signing anything, since you encrypt with the counterparty's public key only) . Both are air gaped / full disk encrypted running OpenBSD, and floating on a battery backup (off the power grid). Basically unplug your UPS from the wall for 15-20 mins while you do this operation, shutdown the computer then plug the APC back in to recharge the batteries. If malware flows in to the decrypt station, it can't return to the transmission station or jump across to the encrypt station. Nothing ever flows in to the Encrypt station only out.

If malware flows in to the decrypt station, it can't return to the transmission station or jump to the encrypt station. Nothing ever flows in to the Encrypt station only out. Nothing flows out of the decrypt station only in.