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Not even we can read it.

Every chat on Pebl is end-to-end encrypted, and there is no way to turn it off. The keys that open your messages are only on your phones.

This is all the server sees.

When a message reaches our server, all we have is who sent it to whom, and when. We cannot see what you wrote: the message is locked on your phone, and only Deniz’s phone can unlock it.

You wrote
Are you at the office at 10 tomorrow?

Common questions

What if my phone is stolen?

The locks keep changing: the keys on a stolen phone do not open old messages, and soon cannot open new ones either. From another device, go to Settings › Sessions and remove the stolen one at once.

How do I know I’m really talking to them?

On their page, tap Safety number. When you are together, scan each other’s code; if it matches, nobody is in between. If it ever changes, you see it in the chat.

What do quantum computers have to do with it?

Someone could record encrypted messages today and try to open them years later with a very powerful computer. Pebl uses two different locks together against that: even if one breaks, the other holds.

What happens to my messages on a new phone?

On your old phone, use Settings › Sessions › Link a device to scan the code on the new one. The locks move over, encrypted. Without the old phone, your account starts again with new locks, and your contacts see that.

Beyond the message

The lock is not only on what you write, but on everything around it.

Photos and files

Where a photo was taken is stripped before it is sent. Every file is locked with its own key before it is uploaded.

Calls

Voice and video calls always go through our server, so the other person never sees your IP address. Sound and video travel encrypted; the server only passes them on. In a one-to-one call, the handshake that sets it up is signed with your chat’s key: if the server tried to step in, the call would not connect. Calls are never recorded.

Notifications

A notification carries no message; it only wakes your phone. Your phone fetches the message and opens it itself.

Link previews

The sender’s phone makes the preview: your phone visits the link’s site, not our server. The preview travels locked inside the message; we never know which links you share.

Pebl Web

Chats are end-to-end encrypted in the browser too. View-once photos never open in the browser, only in Pebl on your phone. Pebl Web runs in one tab per browser.

Backups

Pebl’s chats and keys never go into Google backups or phone-to-phone copies. You move to a new phone by linking it from your old one.

Maps

Maps come through our server; the map service never sees your phone.

Crash reports

If the app crashes, only the error, the app version and the phone model reach us. No messages, names or account. Turn them off in Settings › Privacy › Error reports.

Sessions

You see every phone and browser signed in to your account. Remove one you don’t recognise with one tap; it is cut off at once.

How far along are we?

We finish one step before starting the next. We are also planning an independent security audit.

Messages are locked on the phone; the server carries only the locked formDone
Photos, voice messages and files are locked tooDone
Someone removed from a group cannot read new messagesDone
Safety numbers, and linking a new phone from the old oneDone
Call setup is signed with the chat’s keyDone
Optional screenshot blocking (Settings › Privacy)Done
The message archive on the phone is locked tooPlanned
Your profile name and photo are private tooPlanned

For the curious

You can use Pebl safely without knowing any of this.

Technical details
ProtocolMLS (RFC 9420), with OpenMLS. One-to-one chats and groups work the same way.
Key exchangeX-Wing: ML-KEM-768 and X25519 together (post-quantum hybrid).
EncryptionChaCha20-Poly1305. Media: XChaCha20-Poly1305 with a random 256-bit key per file.
IdentityAn Ed25519 identity key per account; every device is signed with it.
Safety number60 digits, derived from both sides’ keys; a QR code compares both ways at once.
CodeWe do not write our own cryptography: we use only audited parts of OpenMLS and libcrux.
Found a vulnerability? Thank you. Send the details to guvenlik@pebl.im, and please keep it private until it is fixed.Report
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