Depends if you have a BBC micro computer with an LCD monitor (generate your plain text securely) and a hardware encryption/decryption controller with your own encryption/decryption encoder/decoder algorithm on a PICchip micro controller box with an RS432 interface (talks to the BBC micro) to a removable USB flash memory (encrypted files stored on a flash memory card such as an SD card).
You can then send your encrypted files via VPN tunnel or email attachment or upload to FTP server, digital radio modem, direct PSTN modem, infra-red port on a Ericsson SH888 GSM cellular phone etc.
You can even use a DOS program to embed into the noise floor the encryption data of a lossless music file or picture file such as a BMP for hiding in plain sight.
That should keep the NSA on its toes.