> Your solution is certainly better than nothing, but it relies on people having actually used Signal to talk to each other in the past. Well, it is trying to

> Your solution is certainly better than nothing, but it relies on people having actually used Signal to talk to each other in the past. Well, it is trying to incentivise Signal² usage:-) > It also appears to involve a lot of P2P coordination. Not necessarily a huge amount, I think — folks could SMS/email stuff as well as trade contacts face to face, depending on their risk preferences. > it does leak your address book to all of your friends Only where there are overlaps: since it's private set intersection, Alice & Bob only see their mutual acquaintances, not other folks. But yes, the mutual-thereapist issue exists. Presumably an expert mode might enable folks to whitelist/blacklist particular contacts when they're added. Certainly, there are ways in which this approach is worse & more complex than the current Signal approach, but it is better in another way: it preserves privacy from Signal (and its hosting provider, and Intel, and any government which can coërce Signal, its hosting provider and/or Intel into subverting security).