How Zuno keeps your messages private
Your messages are none of Zuno's business. Nine layers of protection keep it that way.
The first five work on their own. The next three ask for a moment of your time, once. The last one keeps watch.
Always on
You don't need to do anything for these.
1 A private connection
Everything Zuno sends and receives travels over an encrypted connection, like the padlock you see in a web browser.
- Protects you from
- people on the same Wi-Fi or network watching your traffic.
2 Messages locked on your device
Every message is encrypted on your device before it's sent. Only the devices in the chat can unlock it. Not Zuno, and not the people who run your account's address. The lock changes regularly, and whenever someone leaves a room.
- Protects you from
- the people who run your account's address, or anyone who breaks in, reading what you say.
3 A key for every device
Each device has its own private mailbox that only it can open. The key to a chat is delivered to every device in it, one mailbox at a time.
- Protects you from
- anyone catching the key on its way.
4 Encrypted calls
Every call gets its own random key, and the audio and video are encrypted before they leave your device. There's no unencrypted fallback: until the key arrives, the call shows “encrypting” and waits.
- Protects you from
- the service that carries the call listening in.
5 Screen privacy
Zuno keeps your chats out of screen recordings and the recent apps preview. Screen privacy is on by default and can be turned off in Settings.
- Protects you from
- other apps recording your screen, and people glancing at your recent apps.
Steps you take once
6 A recovery code
Your keys live on your devices. That keeps your messages private. It also means that if you lose every device you own, your old messages stay locked forever.
A recovery code is the way back. Twelve words, saved somewhere safe. Enter them on a new device and your messages come back. An encrypted backup of your keys is kept with your account, and only this code can open it.
If you lose this code and all your signed-in devices, your message history is gone. Nobody can restore it for you.
Zuno never asks for your recovery code. If a message you're about to send looks like it, Zuno stops and asks first.
- Protects you from
- losing your messages along with your device.
- You do
- save the code somewhere safe.
7 Approving new devices
When you sign in somewhere new, your other devices can't tell it apart from a stranger signing in as you. You approve it by scanning a code between the two devices, or by entering your recovery code. Until then, the new device can't read anything sent before it signed in.
- Protects you from
- someone who learns your password.
- You do
- approve each new device once.
8 Confirming people
Zuno asks your account's address which devices belong to your friend. If the people who run it were dishonest, they could answer with a device of their own and read along. Encryption alone doesn't stop that, because the wrong source was asked.
Confirming someone checks their details through a channel nobody in between controls: in person, by scanning their code, or on a call, by comparing pictures. It only needs doing once per person, even if they change devices later.
- Protects you from
- someone pretending to be your friend, even the people who run your account's address.
- You do
- confirm the people who matter most to you.
A safety net
9 Alerts when something changes
Zuno almost never interrupts you. It does only when something changes that you can act on:
- a new sign-in on your account
- a person whose details changed after you confirmed them
- a new device for a contact who hasn't set up recovery
- Protects you from
- a change slipping by unnoticed.
What encryption can't do
Encryption protects what you say. It doesn't hide who you talk to or when, and it can't stop a screenshot or a compromised device.
Built on
Zuno's encryption comes from Matrix, an open standard for private messaging. Its design is public, so anyone can check how it works instead of taking Zuno's word for it.