Why it matters
iMessage is encrypted between Apple devices — but Apple holds the keys and complies with law enforcement requests. SMS/RCS texts are not encrypted and are trivially interceptable. WhatsApp is end-to-end encrypted but the metadata (who you talk to, when, how often) goes to Meta. Signal is end-to-end encrypted, does not store message content, and does not log metadata. When subpoenaed, Signal has produced exactly two pieces of information: account creation date and last connection date. That is all they have.
Setup — 6 steps, 5 minutes
1
Download Signal
signal.org — free on iOS and Android. Only download from the official Signal website or your phone's official app store. Do not download from any other source.
2
Register with a phone number
Signal requires a phone number to register. If you want more separation, use a Google Voice number. Your real number is not shared with other Signal users unless you choose to share it.
3
Turn on disappearing messages
In any conversation, tap the contact name → Disappearing Messages. Set to 1 week for group chats, 4 weeks for individual contacts as a baseline. Messages that don't exist can't be used against you.
4
Enable Note to Self for secure notes
Use "Note to Self" (your own contact) as a private, encrypted notepad. Anything you don't want on your regular notes app — legal resources, emergency contacts, sensitive plans — lives here.
5
Turn off link previews
Signal settings → Chats → Generate Link Previews: OFF. Link previews load external content and can expose your IP address to whatever server hosts the link.
6
Set a registration lock PIN
Signal settings → Account → Registration Lock. This prevents someone from registering Signal with your phone number — a known SIM-swap attack vector. Set a PIN you will remember.