Everything about how Cipher keeps your messages private — and how to get started.
No. Messages are encrypted and decrypted only on your devices using the Signal Protocol. Our servers store and relay ciphertext — encrypted blobs we have no way to open. We never hold your private keys and never see plaintext.
The Signal Protocol: X3DH for the initial key agreement and the Double Ratchet for ongoing messages. This gives forward secrecy (a stolen key can't decrypt past messages) and post-compromise security (the session heals itself after a compromise). Keys rotate with every message.
Your username, a hashed password, your public prekey bundle (needed so others can start a session with you), and encrypted message blobs waiting for delivery. It never sees message contents, attachments, or your private keys.
No. Cipher is a fully standalone product with its own backend, identity system, database, and infrastructure. It does not share data with or depend on any other service.
No. There are no analytics, no ad pixels, and no third-party fonts or scripts. Even this page loads only from our own server.
No. You create an account with just a username and password. People find you by your handle — there's no phone number and no contact-list upload.
Email is optional. If you add one, it's used only for account verification and password recovery. Without it, keep your password safe — there's no other way back into your account.
Because your keys live on your device, a new device establishes fresh keys. You'll sign back in to your account; new conversations are secured immediately. Message history that existed only on the lost device stays on that device.
A lightweight push notification wakes the app just long enough to fetch the waiting encrypted message. There's no always-on background socket and no polling, so Cipher is easy on your battery.
No. The push is only a wake signal. The actual encrypted message is fetched and decrypted on-device after the app wakes.
Native Android is available now as a direct APK. A web client and a Google Play Store listing are on the way.
Yes. The APK is signed and served directly from our own domain over HTTPS. See the download page for the step-by-step and the file checksum you can verify.
Cipher is free during early access. There are no ads and no data sold — ever.