PliusC3 is a secure messenger built for people who mean it. Messages, calls, files and your personal vault, sealed with post-quantum, device-side cryptography that even our servers can't read.
A full private-comms toolkit in one app: messaging, calls, file transfer, and an encrypted personal vault.
1-to-1 chats encrypted on your device before they ever touch the network. The server only ever sees opaque ciphertext.
WebRTC voice/video over a direct peer connection with DTLS-SRTP media encryption. Call audio flows device-to-device.
Send documents, photos and media end-to-end encrypted over the same channel, direct P2P when both peers are online.
A private space for sensitive files, notes and your calendar, all locked behind the same on-device encryption.
Events, reminders and birthdays with exact on-time alarms and deep-links, stored locally, never synced to the cloud.
Add contacts by scanning a QR code, exchanging identity keys in person so you know exactly who you're talking to.
Every layer assumes the network, and even the server, is hostile. Here's what's standing between your data and everyone else.
Messages use the modern Signal Protocol (libsignal) with a post-quantum PQXDH handshake — classical X3DH combined with Kyber / ML-KEM-1024 — then the Double Ratchet, giving forward secrecy against tomorrow's quantum computers. The server only relays ciphertext it cannot read.
Your identity keys live in the Android Keystore (StrongBox where available), generated and used inside secure hardware, never exported.
Chat history is stored in a SQLCipher database, keyed by a 256-bit secret sealed under a Keystore master key.
Messages can self-destruct on read, are deleted on delivery, and any undelivered copy is purged from the server within hours.
A duress passcode instantly destroys all local data: identity, sessions, the database and its key, leaving nothing to recover.
Every connection is pinned to trusted root CAs, blocking man-in-the-middle interception even if a CA is compromised.
You authenticate by signing a server challenge with your private key. No passwords to phish, and a stolen ID can't impersonate you.
User, device and prekey records are keyed by HMAC-SHA256 hashes, so the database doesn't hold your raw identity in the clear.
Every message is sealed with its own one-time key, derived from a forward-ratcheting chain. No two messages share encryption, so compromising one message’s key leaves every other message sealed.
Share a moment that burns the instant it's viewed. Screenshots are blocked, it stays strictly between the two of you, and vanishes once seen.
No mystery crypto. Standard, audited primitives, applied client-side, end to end.
PliusC3 uses a post-quantum PQXDH prekey bundle — an identity key, a signed prekey, one-time prekeys and a Kyber/ML-KEM-1024 KEM prekey — so a session can be established even when a contact is offline, and stays safe against a future quantum computer harvesting today's traffic to decrypt later. The Double Ratchet then gives every message its own key. Call media rides a separate DTLS-SRTP encrypted P2P channel. Public keys are the only key material the server ever stores.
Take PliusC3's privacy to your whole organization. Self-hosted messaging, a managed VPN and private email, all running on infrastructure you control.
Deploy PliusC3 on your own servers. End-to-end encrypted chat, calls and file transfer for your entire team, with no outside party in the loop.
A WireGuard-based VPN for your organization: secure remote access and encrypted tunnels between offices, sites and devices.
Custom-domain mailboxes on infrastructure you control, with strong encryption and aggressive, minimal data-retention policies.
Dedicated infrastructure, admin controls, onboarding and direct support, tailored to institutions with strict privacy and compliance needs.
Your servers or ours. Run PliusC3 on our hardened, privacy-first servers, or deploy it entirely on a private server your organization owns and trusts.
Install PliusC3 and start communicating on your terms: encrypted, peer-to-peer, and yours alone.
PliusC3 gives you strong content confidentiality. Like any messenger it needs some routing data to deliver your messages, but we don't keep it. The server auto-wipes everything every few hours: any logs we must hold for delivery get purged clean, metadata included. We believe in being honest about what encryption does and doesn't protect.
PliusC3 isn't publicly available yet. To get access or an invite, reach out and we'll get you set up.
Contact sayhello@pliusc3.net