[qnleigh]

I think a verbal password works just fine here. But it has to be something that you are 100% positive the other person wouldn't forget, otherwise it's not effective.

Also sending this article to family members so they're aware of this kind of thing.

[ProllyInfamous]

My problem with this is that it's effectively one-time use, only, if you're a high-enough-value target.

Once you secret is "said" apart, over technology, it could be considered compromát.

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Maybe have your "secret" be about a particular vacation or time period, using a novel recollection dependingupon severity of each conversation.