Secure Messaging App Showdown: WhatsApp vs. Signal

So, you’re interested in secure, encrypted chat apps. You have a few different choices, but as with any chat app, what all your friends are using is important. To that end, Signal and WhatsApp are easily the most popular. Here’s how they compare.

The Contenders

Secure messaging apps are growing in popularity as we all come to realize how much data companies collect about us every day. Unlike phone calls, it’s much easier to imagine some giant corporate entity or government getting ahold of one of your chat transcripts and using it for nefarious means. While many apps out there that do this, including Apple’s iMessage, WhatsApp and Signal lead the way in both popularity, platform availability, and features. Aside from messaging, both apps also include voice and video calling, though we’ll be concentrating on the text messaging capabilities of both here. Let’s break down how both work:

  • Signal: While WhatsApp has the most users between these two, you’ve probably heard about Signal more often in the news whenever people are talking about encryption. Pretty much any article you read about security, from Snowden to Russia, includes a mention of Signal. That’s because every message that’s sent over Signal supports end-to-end encryption (we’ll get into exactly what this means below). This security measure means that if someone intercepted your messages, or found them on a server somewhere, they would see gibberish, not the actual text of a conversation. Signal is also open-source, peer-reviewed, and routinely audited, which means it’s pretty much always up to date from a security standpoint.
  • WhatsApp: WhatsApp has more than 1 billion users, which is an insane number, all things considered. What’s also crazy is the fact that WhatsApp partnered with the company behind Signal, Open Whisper Systems, to integrate the same end-to-end encrypted chat protocol as Signal. Unlike Signal, which bills itself as a security app, WhatsApp bills itself as a messaging application first, which means it has all sorts of silly chat stuff like stickers and GIFs. While the Signal protocol that WhatsApp uses for encryption is open-source, the rest of the app isn’t, so we don’t know everything that happens behind the scenes.

Broad strokes don’t mean much when it comes to actually comparing how these two apps work though, so let’s dig in, starting with the most important part, encryption.

Both Support End-to-End Encryption, But Signal Doesn’t Save Anything It Doesn’t Have To

End-to-end encryption is a term we hear a lot these days, but how it works and why it’s important for security isn’t always clear. Long ago, we sent messages in plain text, meaning that anyone could see the contents of a message if they caught it while it travelled from sender to receiver. Nowadays, many messaging apps using end-to-end encryption. When done correctly, end-to-end encryption prevents a third party from viewing a conversation. It does so by securing a message with a lock, then giving the key to the sender and receiver.

This also means that even the provider, in this case, WhatsApp and Signal, cannot see the contents of a message. So, if a third party, like a government, attempts to access those messages, they can’t see the content of that message; they’ll see a garbled bunch of characters. Both WhatsApp and Signal use the same exact protocols for encryption. That means you can assume your messages are safe and secure regardless of which service you use. How they store personal information and message metadata differs though.

Metadata is the important…