How to Use the Signal App for Secure Messaging

Any message that you send from one device to another, whether it’s an email or a text, doesn’t go directly from point A to point B. Instead, it travels through intermediaries, including a platform provider. Along the route, it potentially can be intercepted and read by people and organizations you never intended to share it with. 

Signal provides end-to-end encryption, meaning that only the sender and receiver can read a message’s content. Not even Signal itself can access your messages. This is not the case for standard SMS texting, or for apps that offer encryption but retain the so-called encryption keys that allow companies to read messages and hand them over to law enforcement, if requested. 

Signal’s data collection practices make the app a safer bet, too. Signal intentionally stores only the minimum amount of metadata required for operation. 

Signal is free to download from the Apple App Store or the Google Play Store onto an iPhone or Android device. Here’s how to use the service’s strongest security and privacy features.

This is a distinguishing feature of Signal. Once the timer you set runs out, any new messages in conversations you started will disappear from both your device and the recipient’s. “You can’t always do that with a regular text message. You may delete it on your end but not the other person’s end,” Grauer says. Ultimately, the fewer messages stored in your conversation history, the less likely they are to somehow be compromised down the road. 

Go to Settings > Privacy > Disappearing Messages. From there, you can select how long you’d like your messages to remain visible after they’ve been viewed, from 1 second up to 4 weeks.

Usernames work a bit differently on Signal than on other platforms. The username is not visible on your profile. Instead, usernames are just a way to initiate contact with other users without sharing your number, upping privacy. You can tell someone your username directly, have them scan a QR code on your phone, or send a link that doesn’t include the username in its text. You can change your username as often as you’d like.

Go to Settings > tap on the circular profile icon and select “Username.” (Your chosen username will be paired with a randomly generated number.)

You can turn off message previews that appear on your phone’s lock screen as notifications. Along the same lines, you can also enable a feature that displays a generic lock screen for Signal when switching between apps—instead of any private information inside the app. This helps prevent someone from catching a glimpse of your messages over your shoulder while you’re navigating on your phone.

Go to Settings > Notifications > Show, and select “Name Only” or “No Name or Content.” Also in Settings, go to Privacy > App Security and toggle on “Hide Screen in App Switcher.”

You can require that your phone password be entered again to open the Signal app. That way, if someone somehow gains access to your device—say, if you accidentally leave your unlocked phone unattended—your Signal messages would still be behind another layer of protection. This feature may be useful to toggle on before heading into a situation, such a protest, where you want an added level of protection, even if you don’t keep it on permanently.

Go to Settings > Privacy. Toggle on “Screen Lock."

To set up a new Signal account, you need to use a verified phone number. By default, your number isn’t displayed on your profile to other Signal users, unless they already have it saved in their contacts. However, by default, people can search for your number in the app and send you a message. You might prefer your number not to be searchable or visible at all, including on your profile or in chats, because a phone number can link your messages to your identity. 

Go to Settings > Privacy > Phone Number, and select "Nobody" under "Who Can See My Number" and "Who Can Find Me By Number." If you choose this option, it’s a good idea to pick a username so that other users can still find and message you, as described above.

If you’re discussing especially sensitive information or have reason to think your communications are at particular risk, you can verify that a Signal conversation isn’t being compromised by a third party by checking that a designated “safety number,” provided by Signal, is the same for both you and your conversation partner. 

To check, open an individual conversation, tap the other person’s name at the top, and select “View Safety Number.” Confirm a match by either scanning the QR code on the other person’s device or cross-checking the numbers. If someone changes phones or reinstalls Signal, you will need to re-verify the safety number.

Signal is a particularly useful tool for community organizing. For example, residents in Minneapolis who are facing increased ICE activity have reportedly relied on the app to coordinate groups that distribute meals and chaperone children to school. 

However, group chats come with more risk. In large groups, it’s easier for someone to be unintentionally added to a chat and go unnoticed. (In 2025, high-ranking U.S. officials made headlines when they accidentally added the editor-in-chief of The Atlantic to a Signal group chat discussing a classified military operation.) Be aware, too, that people in the chat can potentially see your phone number (depending on your settings), profile name, and a photo, if you’ve uploaded one.

You may opt to delete a group chat once it’s served its purpose, or turn on disappearing messages, for added safety.

The most secure password for your phone is random, long, and unique. If your phone is confiscated during a protest, law enforcement can’t legally compel you to reveal your password under the Fifth Amendment. However, your legal protections are shakier when it comes to biometric security. “Police can force you to use your face or fingerprint to unlock a device,” Grauer says, “but they can’t do that for an actual password, because it’s considered the ‘contents of your mind.’” 

You can deactivate biometric passwords quickly, if needed. On an iPhone, press the power button multiple times until you see the shutdown screen. You then need a password to unlock your device.

On Samsung Galaxy phones, hold down the power button and select “Lockdown mode.” However, you first need to enable this feature by going to Settings > Lock screen and AOD > Secure lock settings and toggling on "Show Lockdown mode option."

Any kind of communication, on any platform, can be compromised. Even when using Signal, someone can screenshot or take a picture of your conversation on another person’s phone—or simply read it over your shoulder or another person’s shoulder.

When you’re on a call or videochat, someone can eavesdrop in person. In a group message, a participant you didn’t expect can be added to the chat. Phones can also be compromised by malware or surveillance technology, which you can better defend against by promptly downloading the latest software and security updates. 

Surveillance technology is also constantly evolving, meaning what’s considered secure today may have vulnerabilities in a few months. “There’s never 100 percent certainty,” Grauer says.

For more help protecting your data, consult the free CR Security Planner.