Signal: The Standard for Private Communication
Signal is widely regarded as the most secure messaging app in the world. It is open-source, non-profit, and uses the "Signal Protocol" for end-to-end encryption. However, because Signal collects so little metadata, the security of your account rests almost entirely on your shoulders. If you lose your Signal PIN or lose access to your phone number, Signal cannot "reset" your account for you.
1. Hardening Your Account
The Registration Lock
One of the most common attacks on messaging apps is a SIM swap, where an attacker ports your phone number to their device and then "re-registers" your Signal account. The Policy: Enable the Registration Lock. This requires your Signal PIN to re-register your number on a new device. Even if an attacker has your phone number, they cannot take over your Signal account without your PIN.
Action: Go to Settings > Account > Registration Lock.
Screen Lock and Incognito Keyboard
Signal allows you to add an extra layer of local security.
- Screen Lock: Requires biometrics (FaceID/Fingerprint) or your device passcode to open the Signal app. This protects your messages if you hand your phone to someone else or if it is snatched while unlocked.
- Incognito Keyboard: Prevents your phone's keyboard from "learning" the words you type in Signal, ensuring your private conversations don't end up in your keyboard's auto-correct dictionary.
Safety Numbers: Verifying Your Contacts
Every conversation in Signal has a unique "Safety Number." If this number changes, it means your contact has either reinstalled Signal or someone is attempting a "Man-in-the-Middle" attack. The Strategy: For highly sensitive conversations, verify your safety numbers in person or over a separate video call. Once verified, "Mark as Verified" in the app.
2. Failsafe Recovery Preparation
The Signal PIN: Your Identity Key
Your Signal PIN is NOT a password for your messages; it is an encryption key for your profile, settings, and contacts. Signal does not store your messages on their servers, so the PIN cannot recover your message history. The Rule: Your Signal PIN should be long and unique. If you forget this PIN, you will lose your Signal profile and contacts if you ever switch phones. Store this PIN in your password manager.
Message Backups (Android Only)
On Android, Signal allows you to create an encrypted local backup of your messages. The Risk: This backup is protected by a 30-digit passphrase. If you lose this passphrase, the backup is useless. The Strategy: If you enable backups, you MUST store the 30-digit passphrase in a physical safe or your password manager. Do not store it on the same device as the backup. On iOS, Signal does not support backups (messages are only stored in the secure enclave of the device).
3. Disappearing Messages
The ultimate form of communication security is not storing the data at all. Action: Use "Disappearing Messages" for all sensitive conversations. This ensures that even if a device is seized or compromised in the future, the historical record of your conversation no longer exists.
For more information on the underlying principles, see our articles on MFA Fundamentals and Password Security.
Why This Matters
The Importance of MFA
Multi-Factor Authentication (MFA) is your strongest defense against account takeover. Even if a physical or digital attacker obtains your password, MFA provides a critical second layer of defense that is much harder to bypass. Learn more about MFA best practices.
Unique, Strong Passwords
Never reuse passwords across different services. If one service is breached, every other account using that same password becomes vulnerable to "credential stuffing" attacks. Every online service should have its own unique, long, and complex password managed by a reputable password manager. Learn why unique passwords are critical.