Add another encrypted messaging app to the pile. Today the popular Japanese messaging app LINE announced that it will be able to use end-to-end encryption to protect the content of messages from snooping.
Called “Letter Sealing,” the new feature was announced on the company’s engineering blog.
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The move shows a larger trend of popular messaging apps taking the privacy of their users’ communications more seriously. WhatsApp brought on an implementation of end-to-end encryption back in 2014, and iMessage also supports encrypted messages (even if the service does have some problems). This, and a myriad of apps dedicated to talking privately have emerged—such as Signal and Telegram—largely spurred on by the Edward Snowden revelations.
You may not have heard of LINE, but it has more than 560 million registered users, primarily from Japan, Taiwan, and Thailand, according to Fast Company; 180 million of those are monthly users. It’s not exactly up there with WhatsApp, which has 900 million, but it still has a hefty fanbase.
Letter Sealing uses the Diffie-Hellman (DH) method of exchanging keys—one of the first protocols for sharing keys—and “encryption is performed by the sender instead of the server,” the blog notes.
“Each user holds on to their private keys and only exchanges the public keys with other users. When two public keys are exchanged, obfuscated data is created between the two users. This prevents any third party from intercepting the messages,” the post continues.
As well as the message encryption itself, “Letter Sealing” also makes use of Message Authentication Codes (MAC). This ensures that the message hasn’t been tampered mid-transit by the LINE server.
Motherboard downloaded the app onto two devices, and confirmed that an option exists to display your encryption key fingerprint. This means you can verify that you have been issued the correct key for the person you are talking with, and not surreptitiously been supplied a malicious one by an attacker.
Of course, it would be very unwise to immediately use LINE’s encrypted messaging for anything that was particularly sensitive. Instead, users who have to truly rely on encryption should wait until experts have had a chance to really dig into LINE, or use one of the already established methods for communicating securely.
Indeed, recently one app that wasn’t offering encrypted communications, but was specifically geared to protecting journalists in the field, was discovered to be collecting a wealth of information about its users, and possibly putting them at risk.
“The real concern with encryption software are the more subtle bugs that live deeper in the code,” Matthew Green, assistant professor at Johns Hopkins University told Motherboard in a Twitter direct message.
But if you just fancy having a private chat with your mates, and want to feel reasonably confident that the conversation is really for your eyes only, LINE is now another option to do that. Although users might be getting overwhelmed with the amount of choice when it comes to encrypted messaging, the only real solution to that will be when encryption is the default, rather than the exception. LINE’s new feature is one more step towards that.
