The year is 2037. Government ISP is compromised. Devices are required to have back doors, or else they can't connect to the new system. You can't send anything without it getting sniffed. You use an old system to encrypt a small file, and encode into QR sequence to scan with the new device. This still works for now. You write down the keys to the encrypted message, and securely send to your colleague across the city via pigeon.