- 1:1 and group video calling: The classic Duo end-to-end encrypted experience that involves ringing a number or group directly.
- Meetings: The ability to create or join a cloud-encrypted Google Meet meeting with a link when you're ready. Meet meetings happen in the Duo app.
- Only people in a call or meeting know what's said or shown.
- Google can't view, hear or save audio or video from your call or meeting.
- For 1:1 and group video calling: End-to-end encryption is used to mask data with a code that only you and the other callers can access.
- For Meet meetings in the Duo app: Cloud encryption is used to encrypt your meeting data in transit and stored information in Google's data centres instead of end-to-end encryption.
- Is a standard security method that protects communications data
- Is on by default and can't be turned off
- Only lets people in a call know what's said or shown
- Doesn't allow Google to view, hear or save the audio and video from your call
- Masks the call data with a code that requires a key to decode
Cloud encryption for meetings:
- By default, meeting data in the Duo app is encrypted in transit between the client and Google data centres for any video meetings taking place in Google Duo or Google Meet.
- By default, meeting recordings enabled by a meeting participant are stored in Google Drive and encrypted.
- Meeting encryption adheres to:
- Internet Engineering Task Force security standards for Datagram Transport Layer Security (DTLS)
- Secure Real-time Transport Protocol (SRTP)
Shared secret keys stay on the callers’ devices
Your device decrypts your call’s audio and video with a shared secret key. This key is created on your device and your contact’s device and is deleted after the call ends. It’s not shared with any server.
What’s needed for a shared key
To calculate the shared key, each device needs:
- A private key, which is saved only on your device
- A public key, which is saved on Duo’s servers
The first time you set up Duo, your device creates several private/public key pairs. This way, you’re ready for several end-to-end encrypted calls.
How shared secret keys are created
- The devices exchange their public keys, but don’t reveal their private keys.
- Next, each device uses its private key and the public key from the other device to calculate the shared secret key. They use a mathematical process called cryptography.
Google servers can’t decode your call
When you call someone else on Duo, your call’s audio and video typically go directly from your device to their device. This connection is called peer-to-peer. The call doesn’t go through a Google server.
However, sometimes a peer-to-peer connection isn't available; for example, if a network setting is blocking it. In this case, a Google relay server passes a call’s audio and video between your device and the device you called. The server can’t decode your call because it doesn’t have the shared secret key.
Group calls stay private on the server
Group calls are also end-to-end encrypted. To make sure that group calls are high quality, they go via a Google server.
That server routes everyone’s call audio and video to others in the group. To route calls, the server uses info about your call. For example, which device the video is from. The server doesn't have access to the end-to-end keys and can't decrypt the media.
Group calls use multiple keys
To be part of a call that goes via a server, each group member’s device automatically uses:
- A sender key to encrypt the call’s audio and video. When someone starts a group call, each device exchanges this key with the other devices.
- A client-to-server key to encrypt information about the call. Each device exchanges this key with the server.
What the keys do
The keys work to:
- Encrypt your call’s audio and video so that only other people in the group can hear and see it.
- Decode the audio, video and information from other people in the group call.
Keys can change during group calls
Everyone’s devices exchange new sender keys if either:
- Someone leaves a group
- A person who wasn’t part of the group is added to the group during the call
If a person in the group doesn’t immediately join the group call, their device can still use everyone’s sender keys. This way, that person can join the call at any time while it’s live.
When the group call ends, the keys are deleted.