alt Hacker NewsYou are correct, but you omitted one complication: Clients trust Google's and Apple's servers to faithfully exchange the participants' public keys.
Replies
xmx98 • last Wednesday at 9:50 PM
Sending public keys through the notification system is an unnecessary complication.
soamv • last Wednesday at 9:43 PM
Which clients?
ls612 • last Wednesday at 9:42 PM
Isn’t that what Contact Key Verification solves? Or do I misunderstand how that works?
qurren • last Wednesday at 9:48 PM
... and hold participants' private keys truly private, which you cannot verify without a rooted phone.
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Apps (such as Signal) that care about end-to-end encryption do their own key management. So, Apple / Google servers only ever see ciphertext, and don't have access to the key material that's used for the encryption.