Post-quantum encryption

Speak as if no one were listening.

Because no one is. Messages, calls, video and groups are encrypted end-to-end on your phone and decrypted only on your contact's phone. The server carries bytes it cannot read.

Android 0.9.82 — installed outside the store · iPhone — beta via TestFlight (iOS 26+)

A Anna verified · online Will you make it by 6 pm? 12:04 Yes. Bringing the papers. 12:05 ✓✓ Calling you in a sec 12:05 Picking up End-to-end encrypted Message…
Why Szept

Privacy that doesn't require trust.

We don't ask you to believe us. We build it so there is nothing to believe in — the server simply has no access to anything that matters.

01

Keys stay on the phone

The private key is generated on the device and never leaves it. There is no copy on the server, so there is nothing to steal from the server and nothing to hand over.

02

Ready for the quantum computer

Key agreement is a hybrid of X25519 and ML-KEM-768. Traffic recorded today cannot be decrypted even when classical cryptography is no longer enough.

03

No Google, no ads

Notifications on Android use our own channel, not Google services. There are no ads, no analytics and no profiling — and nothing to build them from.

Security

Privacy isn't a setting you switch on. It's the default.

Every message, call and file is encrypted with its own key, and keys change with every exchange (Double Ratchet). Compromising one key opens neither the past nor the future of a conversation. A change of your contact's identity shows up on screen — you decide whether to trust it.

  • End-to-end AES-256-GCM
  • Post-quantum hybrid X25519 + ML-KEM-768
  • Double Ratchet
  • Data encrypted on the device
  • Contact verification (SAS)
  • Key-change warning
  • Registration lock
  • No ads, no analytics
Features

A full messenger, not just an encryptor.

Everything you expect from an everyday app — except that only the participants can see the content.

Messages and groups

Delivery and read receipts, “typing…” indicator, quoted replies, reactions, edit and delete for everyone, mentions.

Voice and video calls

Voice and video 1:1 and multi-party conferences — end-to-end encrypted, through our own relay, with no intermediaries. The highest audio and video quality compared with other messengers.

Attachments up to 200 MB

Photos, files and voice messages, each encrypted with its own key. The server keeps only the ciphertext and deletes it after a while.

Disappearing messages

Set a lifetime for a conversation — messages are deleted on both sides. Plus search in history.

Tidy conversations

Pinning, muting, archiving, forwarding and names straight from your phone book.

Notifications without Google

On Android, our own push (UnifiedPush/ntfy) — ringing and messages in the background without Google services. On iPhone, the native call screen (CallKit).

For business and institutions

Your own server. Your own keys. Your own rules.

We will set up a dedicated Szept instance for your organisation — on-premise or in a private cloud, with an isolated user base, an admin panel and full control over keys. Integration with existing communication infrastructure is possible.

  • On-premise or private-cloud server
  • Integration with telecom infrastructure
  • SMS/OTP gateways, VoIP/SIP, radio systems (e.g. TETRA)
  • Admin panel and account management
  • Full control over keys and data
  • Your own branding and security policies
Ask about deployment

Start whispering.

Download, enter your number, type the SMS code. That's it.

Android version: 0.9.82