Whether your private conversations are personal, professional, or political, what you say or type into your phone may be of interest to snooping governments, both foreign and domestic. Criminals might be interested as well, especially when you send someone a password or credit card number. There are others you might worry about too: You might want to apply for a job without your current employer finding out. You might discuss something with a lawyer. You might talk to your friends about attending a protest, getting an abortion, or buying a gun. You might send private selfies to your partner that you don’t want anyone else to see. You might be dating someone new and not want your coworkers to find out. The list goes on.
Fortunately, privacy is a fundamental human right.
Unfortunately, most ways that people communicate with their phones — voice calls, SMS messages, email, Facebook, Skype, Hangouts, etc. — are not as private as you might think. Your phone company, internet provider, and the corporations that make the apps you use to communicate can spy on what you say. Your chats can be accessed by police, the FBI, and spy agencies like the NSA. They can also be seen by anyone who can pick up your phone and sift through it. Some of them can even be read by anyone in a position to simply glance at your phone’s lock screen and read the notifications displayed there.
But it’s possible to make sure that your private conversations are actually private. It starts with installing an app known as Signal, and getting your friends to install it too. Then you’ll want to tweak the settings to lock everything down.
The Signal app is easy to use, works on both Apple’s mobile operating system iOS and Google’s Android, and encrypts communications so that only you and the people you’re talking to can decipher them. It also has open source code, so experts can verify its security claims. You can download Signal from the Android Play Store and the iPhone App Store.
Although Signal is well-designed, there are extra steps you must take if you want to maximize the security of your most sensitive conversations. (I outlined some of these steps last year, but Signal has changed significantly since then.) There are also some useful features in Signal that you might not know about.
Get your friends to use Signal
Lock down your phone
Hide Signal messages on your lock screen
Don’t retain your messages forever
Send and receive private photos and videos
Have secure group discussions
Make secure voice and video calls
Send messages to numbers without adding them to your contacts
Verify that the encryption isn’t under attack using safety numbers
Using Signal on your computer
Get Your Friends to Use Signal
You can only send encrypted messages, and make encrypted calls, to other people who are on Signal. There’s not much point in having Signal if all of your most private texts are still going over unencrypted SMS, so get your friends to install the app, too.
If you’re an activist, get everyone at your next meeting to install the app. If you’re a journalist, tell your sources and editors. If you’re running for office, consider using Signal to communicate with your campaign staff.
Lock Down Your Phone
Signal uses strong end-to-end encryption, which, when properly verified, ensures that no one involved in facilitating your conversation can see what you’re saying — not the makers of Signal, not your cellphone or broadband provider, and not the NSA or another spy agency that collects internet traffic in bulk.
But Signal’s encryption can’t stop someone from picking up your phone and opening the app to read through your conversations. For that, you need to configure your phone to require a passcode, or some other form of authentication, to unlock. You should also make sure that the storage on your phone is encrypted and that you update your phone’s operating system and apps promptly, which makes it significantly harder for anyone to remotely hack into your phone.