00 Anonymous messaging protocol
No name. No number. Just your message.
SML is an anonymous, post-quantum messaging protocol and client family. You hand over no personal information when you sign up — because the system has no use for it.
01 Identity
11 digits
This is the only thing the server knows you by.
example sml_id421 8419 6620
No phone number, no email, no name. Your account is nothing more than an 11-digit sml_id, and there is no personal data record standing behind it on the server.
02 Data
0 personal data
- It does not scan your contacts.
- It does not upload your address book to the server.
- It does not match you with anyone automatically.
03 Reach
Not everyone
can reach
you.
By default only your contacts can write to you. When someone you don't know sends a message it is not a notification but a request, and it waits to one side. No conversation begins until you accept it.
04 Session setup
Record it today.
You still cannot
open it tomorrow.
PQ-X3DH Kyber + X25519
Session keys are established through a hybrid key exchange: a classical elliptic curve and lattice-based encapsulation working side by side. This is designed against the attack model that records traffic today and waits to open it later with a quantum computer.
05 Message keys
A new key
for every message.
Double Ratchet turns the key chain one notch forward with every message sent. Even if a single key is compromised, past messages stay closed — and the chain rebuilds itself within a few messages.
Protocol at a glance
- Key exchange
- PQ-X3DH · Kyber + X25519 hybrid
- Message keys
- Double Ratchet
- Groups
- MLS · RFC 9420
- Identity
- 11-digit sml_id
- Verification
- Safety number + QR
- Calls
- 1:1 voice and video
06 Client
The complexity sits underneath.
On top, only conversation.
Cryptography stays out of the interface. Chat list, messages, voice notes, media — everything familiar is exactly where you expect it.
Interface preview — final visuals will land closer to release.
07 Difference
The usual model.
And SML.
-
Sign up with a phone number11-digit sml_id -
Address book scanning, automatic matchingNone -
Personal data record on the serverNo PII on the server -
Classical key exchange onlyPost-quantum hybrid -
Anyone can reach you unaskedStrangers arrive as requests
08 Verification
Not a promise,
a number.
Every conversation carries a safety number that must be identical on both sides. Compare it, or scan the QR code. If it matches, nobody has stepped into the line between you.
example safety number
09 Clients
Every platform,
one core.
- iOS
- Android
- Web
- Windows
- Linux
They all run the same protocol core. Encryption behaviour and security guarantees do not change from one platform to another.
10 Frequently asked
Short answers.
What do I need in order to sign up?
Nothing. No phone number, no email address and no name is requested. At sign-up you receive an 11-digit sml_id; that is the whole of your identity.
Who can find me?
By default only your contacts. There is no address book scanning and no automatic matching. Messages from someone you do not know pile up as requests rather than conversations.
What does “post-quantum” actually mean?
Sessions are established with PQ-X3DH: Kyber and X25519 together, as a hybrid. The goal is protection against an attacker who records encrypted traffic today and hopes to open it later with a quantum computer.
How often do keys change?
With every message. Double Ratchet renews the key for each message sent, which provides both forward secrecy and post-compromise recovery.
How are groups encrypted?
Groups are built on MLS (RFC 9420) — a standard group encryption protocol in which the key tree is updated as group membership changes.
Are there voice and video calls?
The first release has 1:1 voice and video calls. Group calls will follow in a later release.
How do I know the other side is really that person?
Every conversation has a safety number. It must be the same on both sides; when you are face to face you can also verify it by scanning the QR code.
When will I be able to use it?
SML is being worked on and will not be released before it is finished. Download links for the iOS, Android, web, Windows and Linux clients will appear on this page once they are ready.
You do not have to say
who you are
in order to talk.
SML