How Do Encrypted Messaging Apps Work?

Encrypted messaging apps like Signal, Telegram, and WhatsApp make sending and receiving messages more secure. But how do these apps work? Which features make them more secure, and should you start using one?

Let’s look at what’s behind encrypted messaging apps so you can decide for yourself — are they worth it?

What is end-to-end encryption?

In messaging apps, encryption is taking your messages, scrambling them up so they’re indecipherable gibberish, and sending them. If third parties somehow get a hold of your message, they can’t read it without a key.

End-to-end encryption means your messages are scrambled from the time you send them until the time your recipient opens them (from “end to end”). Why is end-to-end encryption better than just regular encryption? If your message is unscrambled at any point on its journey to your recipient, a hacker can read it if they intercept it. Therefore, a service provider that keeps your message encrypted from end to end provides you with more privacy.

Also, if an app has end-to-end encryption, even the servers that transmit the message cannot unscramble it. So, providers of messaging apps shouldn’t have the ability to read your encrypted messages. Finally, it’s worth noting that for encrypted messaging apps to work, both parties must be using the same app. If not, the message doesn’t stay encrypted.

Public key encryption vs. private key encryption

Encrypted messaging apps rely on the use of public and private keys. Public key encryption (also known as asymmetric encryption) uses two keys: a public key and a matching private key. The user sends a message, using their public key to encrypt it. The recipient of the message then uses the matching private key to decrypt and read the message. With this method, only one key can encrypt and only one key can decrypt.

Private key encryption (also known as symmetric encryption) also uses two keys. But both keys can be used to either encrypt or decrypt the message. Both of these keys are private keys.

Secure messaging apps have traditionally been based on asymmetric encryption, but today many of them use more advanced encryption methods. The popular encrypted messaging app Signal, for example, also incorporates permanent, temporary, and shared keys to add even more layers of security. WhatsApp uses the same encryption protocol as Signal.

Features of encrypted messaging apps

Encryption is essential, but it’s only one element of what makes secure messaging apps secure. Other common features include:

No data logs: Truly secure messaging apps won’t save any of your data. That includes the messages themselves as well as metadata. Metadata would be a geolocation or time stamp on your message. Some messaging apps even let you sign up without giving an email address or phone number — so the company has zero information about you. Not all apps have the same data logging policies, however, so check before you start using one.
Self-destructing messages: The best secure messaging apps have an auto-destruct feature — yes, just like in spy movies but far less dramatic. Some messages self-destruct after the recipient opens them, but other apps allow you to set a time frame. You can configure messages to auto-delete after one minute, or two, or ten, whether the recipient has read them or not. Some messaging apps will even let you configure different self-destruct settings for different conversations. Keep in mind, however, that many secure messaging apps do not prevent recipients from taking screenshots.
Open-source: Open-source apps publish their encryption protocols and code for anyone to see. Open-source projects also allow anyone to verify their code and suggest modifications. Apps and software that are open-source are often considered more reliable from a security standpoint because they’re transparent and vetted by security experts. Signal is open-source and since it’s such a popular app, it gets reviewed regularly.

Why you should use encrypted messaging apps

After learning about encryption methods, data logs, and self-destruct messages, you might be thinking that using a secure messaging app is too complicated to be worth it. In fact, most of the features that make these apps secure are “behind the scenes.” There’s nothing you need to do concerning encryption, other than enable the option in some apps. You use Signal or Telegram like you would a regular messaging app. On the whole, encrypted messaging apps are user-friendly. Some apps may have a sleeker user interface than others, but you won’t have to enter codes into the command line to send encrypted messages.

Encrypted messaging apps keep your private info private. You may think of yourself as someone “with nothing to hide,” but that’s not really true. You likely have things you’d prefer to keep private. You wouldn’t want a stranger to see your credit card number, health information, vacation plans, or account passwords. What if someone with malicious intent gets access to this information?

Protecting your privacy

It might not seem like you include sensitive information in your text messages, but you’d be surprised how much your conversations can give away about you. While secure messaging apps do have some flaws, they’re a huge step in the right direction for maintaining your privacy. Now that you know how they work, you can start using an encrypted messaging app for all your personal communications.