Over the past decade, Signal has proven itself to be the messaging platform of choice for security concious users, and the one that we recommend. Run by a non-profit organisation, there are no instances of user data vewing leaked, stolen, stored or compromised, and the open source nature of the software means that anybody with enough time and expertise can audit the underlying code. Activists, journalists, officials and people across the world who value their privacy use Signal to communicate securely.
In this article we explain some of Signal’s security features and outline how best to use them so they keep you and your friends secure.
User names
In early 2024, Signal took a significant step forward with the launch of user names as unique identifiers. Whereas previously the phone number of each user was previously visible, users are now able to be part of personal and group chats without having to disclose their phone number. When set up properly with a pseudonymous profile name, this makes it impossible for individuals to be personally identified through their Signal account alone.
Each Signal account has two identifiers: the user name and the profile name.
Consisting of a name and then a number seperated by a period, the user name is your unique identifier, tied to your phone number but unlike a phone number the authorities cannot trace it to you, your device or your location just through this information alone.
Your profile name can be anything and not unique, it can include emojis, spaces and other characters which cannot be included in usernames, but bear in mind that this name is visible to everybody that contacts you and everybody on the group chats you’re a part of, so it’s best not to use your real name or initials, however convenient it might be.
How to keep your details secure on Signal
In the menu option Settings → Privacy → Phone number you should not allow people to see your number, and for extra security you should not allow people to find you by number either. This means that people must use your user name to contact you on Signal. You can find a QR code and URL link to your profile by going to Settings and then tapping on your profile information, this makes it easier for you to share your contact with others.
More information can be found here on the Signal support pages, where you will find more advice and FAQs. It’s worth a browse, especially if you are new to Signal.
Disappearing messages
You wouldn’t record and keep your sensitive phone calls, so why would you keep your messages forever? Make them disappear! Set the disappearing messages on each chat to the shortest acceptable period. Individual messages can always be deleted regardless of disappearing mesasages length. Bear in mind that disappearing messages only take effect after the timer is set, and anything before that will stay on the device until manually deleted.
So that you don’t forget to enable disappearing messages on each new chat you start, we recommend setting a default timer in Settings → Privacy → Default timer for new chats.
It is a good idea to simply delete all messages on the device from time to time. Be honest and ask yourself: do you really need lots of messages from months ago that you didn’t really want in the first place? Go to Settings → Data and Storage → Manage storage → Delete message history and be done with them.
Call instead?
They’re a bit passé, but calls leave no trace on the phone, other than a call history which can be permanently deleted. Another advantage of calls over text is that you can be sure you are speaking to the person you are in contact with.
‘Relay’ call for added security
This setting is potentially useful, but only if you are making a voice, video or screen sharing call to someone you don’t already know and trust. If turned on, it will route your calls through the Signal servers so as not to set up a direct connection to the recipient’s IP address, which could expose your identiity and location. The disadvantage of using this setting is that it can affect call quality and latency (time delay).
This setting doesn’t affect messages, which always go through the Signal servers, never peer-to-peer.
Molly
For those wanting the ultimate in Signal security, the Molly app is an offshoot of Signal for Android devices. Molly expands on the existing code and adds extra security features such as automatic lock and enhanced message database security. The interface and user experience is virtually the same as Signal, the biggest difference being some extra menu items. You can talk to everyone on Signal and even link it to the Signal desktop app for your computer, just like you can with the vanilla Signal. As long as your phone supports it, there’s no reason not to use it.
Of course, messaging is just one area of digital security and doesn’t mean that you shouldn’t practice good security in other areas, both on- and offline. Check out our other guides for more tips and advice.
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