alt Hacker NewsOne possible solution is to only be able to contact someone if you have received an invitation code from them out of band. E.g. "scan this QR code to add me on signal". Such an invitation code should default to single-use but users should be allowed to generate standing invitations so that businesses and the like can print and post one in their store or whatever. Start getting spam from one of your standing invitations? Just revoke it and make a new one. Presumably the Signal folks can come up with more alternative solutions than the half baked one I came up with after thinking about it for a minute, they're clever cookies.
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Requiring manual key verification is a bad design that doesn't scale or benefit most people.
Imagine setting up a chat for an organization you're working with - will you be willing to process 20 out-of-band QR codes? 50?
On a smaller scale, it's clear that Signal believes a functioning address book is necessary for end user adoption. For example, by default Signal notifies you of people in your phone contacts who are on or who later join Signal.
> Presumably the Signal folks can come up with more alternative solutions
I have yet to see a solution better than the one they chose, for their requirements. Notice that there are none in this discussion.
Welcome back to “key signing parties”. PGP never got enough adoption. At least Signal is simple enough that the (ahem) leaders of the US can (mostly) manage to use it.