Signal encrypts messages, voice, and video by default. The protocol is open. WhatsApp uses a cousin of it. Sealed sender hides your identity from Signal’s servers on ordinary messages. Since 2023 the handshake also includes a post-quantum layer, PQXDH, so a recording of today’s traffic is harder to crack later with a future quantum machine.
You still register with a phone number. Usernames mean you no longer have to show that number to every contact, but the number is how the account exists. The Signal Foundation is a US nonprofit. One organization holds the network. That is a smaller risk than Meta, and it is still one point. PIN and registration lock matter, because the number can be SIM-swapped.
Use it for family and anyone who will actually install it. signal.org
Turn on registration lock so a SIM swap cannot steal the account with only the SMS code. The PIN is not a password for your chats. It locks registration. Use usernames so you stop pasting your phone number into groups. Disappearing messages are a convenience, not a promise that the other person’s phone deleted screenshots. Signal still cannot protect a conversation the other party pastes into a group chat elsewhere.
