Privacy at Radex is not a setting. It's how the system is built.
Radex messages use libsignal, the same open-source library that protects Signal: PQXDH to start each conversation (X25519 plus Kyber-1024, so recorded traffic stays safe even against future quantum computers), then the Double Ratchet, which gives every message its own key.
Your phone generates its own identity key and pre-keys when you create your account. Only public keys are uploaded, so others can start a conversation with you. Each one-time pre-key is used for a single conversation, then deleted.
Message keys are thrown away after use. Even if a phone were compromised later, earlier messages could not be decrypted from it.
Voice and video calls are encrypted end to end twice: WebRTC's DTLS-SRTP, set up through your encrypted chat, and a second AES-GCM layer on every audio and video frame with a fresh key per call. Relay servers only ever forward ciphertext.
Radex's servers hold encrypted envelopes until your phone picks them up, then delete them. They never have the keys to open them. Messages are padded so their length reveals less.
Each conversation has a safety number (60 digits). If it's the same on both phones, no one is in the middle. If someone's key changes, the chat tells you.
Messages, sessions and keys stored on your phone are encrypted with a key held in the Android Keystore.
libsignal is published under the AGPL-3.0 license. Radex is built on it and its source code will be published under the same license, so anyone can check these claims.
Hiding who talks to whom from our own servers (sealed sender), and using one account on several devices.