Eww y'all have a code word? Those are easily guessable.
My wife and I have a random 6 digit code that rotates every 30-seconds based on an algorithm and if we don't properly authorize, we will refuse the connection.
It is not a joke. Honestly I don’t remember anymore if we had a code word or not, but it was definitely discussed with parents and school officials; probably in D.A.R.E too. The premise is that a kidnapper might try to trick you with: “Your mom is [working late / in the hospital / etc.], she asked me to pick you up today.” If they don’t have the password, then you don’t go with them and then go get help from a trusted adult. If you can’t get to one, run away and scream.
You receive a call from an unknown number and they tell you they've kidnapped your wife. They then give her the phone so you can hear her but she didn't do it through Signal so she's obviously not your wife so you just hang up.
And that's not how you establish a PKI or implement AE (authenticated encryption).
When I send a voice message e.g. I don't verbally sign it, that's actually part of KE (key exchange) protocol.
Same applies to non encrypted, authenticated communication of course.
And in case you are talking about physical face to face communication: I think you'd recognize your family and friends without the help of cryptography.
Edit: if you have any question, feel free to ask! Maybe I misunderstood you? Then I'm sorry
Between this and the recommendation to fall back to encrypted communication, this almost looks like someone trying to bootstrap a populace trained to evade the feds.
The scam is exactly about feinting a "good reason". So it is still a good idea to establish a code phrase for such situation, even if you don't normally use the phone.
Except theres not cause the MAGAts are out drooling on the streets, in your workplace, and at the cornerstore 24/7 making sure you know their silver spooned, first-generation immigrant, traitor is For The People.
I just tell them to hang up and call me right back. In some scenarios that might not be the best solution but it is the easiest blanket approach that I can find to keep everyone safe.