Strong End-to-End Encryption Comes to Discord Calls

We’re happy to see that Discord will soon start offering a form of end-to-end encryption dubbed “DAVE” for its voice and video chats. This puts some of Discord’s audio and video offerings in line with Zoom, and separates it from tools like Slack and Microsoft Teams, which do not offer end-to-end encryption for video, voice, or any other communications on those apps. This is a strong step forward, and Discord can do even more to protect its users’ communications.

End-to-end encryption is used by many chat apps for both text and video offerings, including WhatsApp, iMessage, Signal, and Facebook Messenger. But Discord operates differently than most of those, since alongside private and group text, video, and audio chats, it also encompasses large scale public channels on individual servers operated by Discord. Going forward, audio and video will be end-to-end encrypted, but text, including both group channels and private messages, will not.

When a call is end-to-end encrypted, you’ll see a green lock icon. While it's not required to use the service, Discord also offers a way to optionally verify that the strong encryption a call is using is not being tampered with or eavesdropped on. During a call, one person can pull up the “Voice Privacy Code,” and send it over to everyone else on the line—preferably in a different chat app, like Signal—to confirm no one is compromising participants’ use of end-to-end encryption. This is a way to ensure someone is not impersonating someone and/or listening in to a conversation.

By default, you have to do this every time you initiate a call if you wish to verify the communication has strong security. There is an option to enable persistent verification keys, which means your chat partners only have to verify you on each device you own (e.g. if you sometimes call from a phone and sometimes from a computer, they’ll want to verify for each).

Key management is a hard problem in both the design and implementation of cryptographic protocols. Making sure the same encryption keys are shared across multiple devices in a secure way, as well as reliably discovered in a secure way by conversation partners, is no trivial task. Other apps such as Signal require some manual user interaction to ensure the sharing of key-material across multiple devices is done in a secure way. Discord has chosen to avoid this process for the sake of usability, so that even if you do choose to enable persistent verification keys, the keys on separate devices you own will be different.

While this is an understandable trade-off, we hope Discord takes an extra step to allow users who have heightened security concerns the ability to share their persistent keys across devices. For the sake of usability, they could by default generate separate keys for each device while making sharing keys across them an extra step. This will avoid the associated risk of your conversation partners seeing you’re using the same device across multiple calls. We believe making the use of persistent keys easier and cross-device will make things safer for users as well: they will only have to verify the key for their conversation partners once, instead of for every call they make.

Discord has performed the protocol design and implementation of DAVE in a solidly transparent way, including publishing the protocol whitepaper, the open-source library, commissioning an audit from well-regarded outside researchers, and expanding their bug-bounty program to include rewarding any security researchers who report a vulnerability in the DAVE protocol. This is the sort of transparency we feel is required when rolling out encryption like this, and we applaud this approach.

But we’re disappointed that, citing the need for content moderation, Discord has decided not to extend end-to-end encryption offerings to include private messages or group chats. In a statement to TechCrunch, they reiterated