Sentrix
SENTRIX · End-to-end encrypted communication

Communication without compromise.

Messaging, voice, video and files closed end to end, for organisations that cannot put their communications on a consumer platform. Deployed on your own infrastructure, with message keys that never leave the device.

Closed end to endMessagingVoiceVideoFiles
One-to-one
Signal
The official Signal Protocol library, not a re-implementation
Groups
MLS
RFC 9420 via OpenMLS, built to scale past sender keys
Runs on
Your kit
Docker or Kubernetes, on infrastructure you control
Message keys
On device
Generated there, and never sent anywhere
Cryptography

The protocols are named, because that is the only claim worth making.

Sentrix does not roll its own cryptography. One-to-one messaging uses the official Signal Protocol library; group messaging uses MLS, the IETF standard. Both are named here so they can be checked rather than believed.

One-to-one
Signal Protocol via the official libsignal library — X3DH key agreement, Double Ratchet, X25519, and AES-256-CBC with HMAC-SHA256.
Groups
MLS (RFC 9420) through OpenMLS, which scales to large groups far better than sender-key schemes.
Media
AES-256-CTR with encrypt-then-MAC, the per-file key carried inside the already-encrypted message. The server stores a blob it cannot open.
At rest
An encrypted local database on the device, with the identity key wrapped by the platform keystore.
In transit
TLS with certificate pinning baked into each build, request attestation and timestamp anti-replay.
Key custody
The server holds public key material and pre-key bundles only. Message keys are generated on the device and never leave it, and encrypted backups are opaque to the operator.

Stated precisely: the operator cannot read message content. Administrators do retain the operational controls below, and an organisation's broadcast-announcement key is held server-side — deliberately, so administrators can address their own organisation.

What it does

A messenger people will actually use.

Secure tools fail when they are worse to use than the consumer app they replace. Sentrix ships the features people expect, rather than asking them to give things up in the name of security.

One-to-one and group messaging
With editing, replies, starring, deletion and full history search.
Voice and video calls
WebRTC, with the signalling itself carried inside the encrypted channel.
Multi-party calls
Through a selective forwarding unit, for groups rather than pairs.
Files and voice messages
Photos, documents and audio, encrypted client-side.
Self-destruct timers
Per conversation, with a maximum an administrator can enforce.
Safety numbers
Verify a contact in person by QR, so a swapped key is visible.
Delivery and read receipts
Including typing indicators, queued correctly when a recipient is offline.
Urdu and right-to-left
A first-class layout, not an afterthought.

Sentrix ships as a hardened Android client, distributed through your MDM rather than a public app store. There is no iOS client today.

Control

Everything an administrator needs, and a record of every use.

The distinction that matters: administrators control devices, membership and policy — they never gain the ability to read a conversation.

Screenshot blocking
Enforced by the client, with capture attempts recorded.
Root and tamper detection
Compromised devices can be blocked from connecting at all.
Accessibility and clipboard guards
Close the routes screen-scrapers actually use.
Panic PIN
A duress code that silently wipes, and a wipe after repeated failed attempts.
Remote device control
Suspend a user, reset a PIN, revoke a session or wipe a device.
Kill outdated builds
Refuse connections from client versions you have retired.
Policy engine
Around fifty settings across authentication, cryptography, messaging, media, compliance and network — layered from system to organisation to group to user.
Audit
Retention-bounded logs of administrative action, with configurable capture and clipboard auditing.
Deployment

On infrastructure you control.

Model
Self-hosted. Docker Compose and Swarm, or Kubernetes manifests for a cluster you already run.
Footprint
An application server, a database and a cache behind a reverse proxy, plus a relay for calls.
Distribution
A signed Android package delivered through your own MDM or download portal.
Tenancy
Organisation-scoped identity, policy and audit, with role-based administration.

Sentrix has been through internal security review and hardening. It has not had a third-party audit or penetration test, and we would rather tell you that than let you assume otherwise.

Common questions

The things people ask before a briefing.

What encryption does it use?

The official Signal Protocol library for one-to-one conversations — X3DH, Double Ratchet, X25519, AES-256 with HMAC-SHA256 — and MLS (RFC 9420) via OpenMLS for groups. Neither is a re-implementation.

Is there an iOS app?

Not today. Sentrix ships as a hardened Android client, distributed through your own MDM rather than a public app store.

Can the operator read messages?

No. Message keys are generated on the device and never leave it, and the server stores only public key material and opaque encrypted blobs. Administrators do retain operational controls — suspend, PIN reset, session revoke and remote wipe — and an organisation's broadcast-announcement key is held server-side so administrators can address their own organisation.

Where does it run?

On your infrastructure. Docker Compose or Swarm, or Kubernetes, with PostgreSQL, Redis and a TURN relay for calls.

Has it been independently audited?

It has been through internal security review and hardening, but it has not had a third-party audit or penetration test. We would rather tell you that than let you assume otherwise.

See it on your own network.

Sentrix is deployed into your infrastructure, so an evaluation is a real deployment on your terms. We will walk through the architecture, the key custody model and what your administrators can and cannot do.