Well, sorta. I ruled it out because hardware of that era, limited by Voyager’s power supply, could not do encrypted communication beyond wet paper bag levels.

Buy encrypted communication is all based on same as a passkey in the end (a sequence of secret bytes), whether we are talking encryption based off public/private keys, symmetric keys, elliptic curve, passphrases etc, so it’s comparable enough for the point I was aiming for. :)