What end-to-end encryption is, and why you need it

What end-to-end encryption protects against

The main advantage of end-to-end encryption is its restriction of transmitted data from anyone but the recipient. It is as if when you mailed a letter you put it in a box that was physically impossible to open — immune to any sledgehammer, saw, lockpick, and so forth — except by the addressee. End-to-end encryption ensures the privacy of your communication.

Creating an invincible box isn’t really possible in the physical world, but in the world of information it is. Expert mathematicians are constantly developing new encryption systems and improving the strength of old ones.

Another advantage follows from end-to-end encrypted messages being undecryptable by anyone other than the recipient: No one can change the message. Modern encryption methods work in such a way that if someone changes the encrypted data, the message becomes garbled on decryption, making the problem instantly clear. There is no way to make predictable changes to an encrypted message — that is, it’s impossible to replace the text.

That ensures the integrity of your communication. If you receive a successfully decrypted message, you can be sure it’s the same message that was sent to you and that it wasn’t somehow tampered with in transit (in fact, a messaging app will do that for you automatically).

What end-to-end encryption doesn’t protect against

After learning about the benefits of end-to-end encryption, readers might get the impression that it’s the solution to every information-transfer problem. It isn’t, though; end-to-end encryption has limitations.

First, although the use of end-to-end encryption lets you hide the content of your message, that you sent a message to a certain person (or received one from them) will be apparent. The server can’t read the messages, but it is definitely aware that you exchanged messages on a certain day and at a certain time. In some cases, merely communicating with particular people may draw unwanted attention.

Second, if someone gains access to the device you use to communicate, they will be able to read all of your messages, as well as write and send messages on your behalf. Therefore, protecting end-to-end encryption requires the protection of devices and application access — even if only with a PIN code — so that if the device is lost or stolen, your correspondence, along with the ability to impersonate you, does not fall into the wrong hands.

For that reason, devices need to be protected with antivirus software. Malware on a smartphone can read the correspondence on it just as if a living person had physical possession of your phone. That is true regardless of what kind of encryption you use to send and receive messages.

Third and finally, even if you take perfect care of protecting all your devices, and you know for sure no one has access to the messages on them, you can’t be certain about your conversation partner’s device. End-to-end encryption is no help there.

Despite its limitations, end-to-end encryption is currently the most secure way to transfer confidential data, and that’s why more and more communication services are switching to it. That’s a good thing.