End-to-end encryption built on the national cryptographic standards of Ukraine. No accounts. No phone numbers. Nothing the server can read.
SKLO is the Ukrainian word for “glass”: transparent to you, impenetrable to outsiders. The messenger is built entirely on Ukrainian cryptographic standards (DSTU) — the same ones approved for the protection of state information. The elliptic-curve arithmetic and the algorithm implementations were built by our engineers over decades — this is not a wrapper around someone else’s library, but an engine of our own.
Our server is a simple relay. It sees who is online and where a packet is headed, and — if you are offline — it may briefly hold the encrypted packet until you reconnect. It can read none of it.
The one thing it holds: when you are offline, the relay buffers the encrypted packet — undecryptable ciphertext plus the routing metadata it already sees — and delivers it when you reconnect, then deletes it. The buffer is capped per user and expires automatically. Even while held, the content stays unreadable to the server.
History, contacts and keys live only on your device, sealed under your master password with a memory-hard key derivation (Argon2id). Without it, no one can read them — not the phone, and not us.
Not independently audited — yet. The engine is cross-checked byte-for-byte against independent implementations and tested from an attacker's perspective, but it has not been through a third-party security audit or a constant-time review. We will keep saying so until that changes.
| Task | Standard |
|---|---|
| Hashing & key derivation | Kupyna / DSTU 7564 |
| Encryption | Kalyna / DSTU 7624 (AEAD) |
| Digital signatures | DSTU 4145 (M257_PB) |
| Key exchange | ECDH on the E512/1 curve (DSTU 9041) |
| Password sealing | Argon2id · RFC 9106 |
| Conversation secrecy | Double Ratchet — a new key for every message |
Send files up to 200 MB — chunked, streamed and encrypted end-to-end, with no size games and no cloud middlemen.
Your identity, contacts and history are exported into a single encrypted file. Restore on any device with your master password — recovery is purely between you and your password.
Slide and hold for three seconds — identity, contacts and history are erased beyond recovery. Releasing early cancels.
Five minutes of inactivity wipes private material from memory and returns you to the lock screen. Manual lock any time.
On iPhone, keys are wrapped in the Secure Enclave and unlocked with Face ID — hardware-backed protection on top of the master password.
Contact identities are exchanged as DSTU-signed bundles — a forwarder cannot swap a name onto someone else’s key without breaking the signature.
Not a chat client. It opens the encrypted .skar vault archive your iPhone exports — with your recovery file and master password, entirely in memory, writing nothing down and making no network request once the page has loaded. Browser delivery cannot be made safe against a compromised host, and that is exactly why the messenger itself lives on iOS.
Open sklo.me →A fully native Swift app with the same cryptographic core compiled for ARM64 — byte-exact parity with the web build, plus Face ID, Secure Enclave and hardware-backed key storage. Messages, files and groups live here.
Ask about early access →No sign-up, no phone number. The messenger is on iPhone — write to us for TestFlight access. Already holding a vault archive? Open it straight in your browser, with nothing to install.
