Security architecture
Built so it can't be
turned against you.
We designed the system so that trusting us isn't required. This page says what we hold, what we can refuse, and what we can't do, including the parts most vendors leave out.
The guarantees
Sealed on your device
Keys are generated and used in your browser. What travels to us, and what rests on our servers, is sealed data we have no way to open.
Post-quantum in the critical path
Every message is sealed with ML-KEM-1024, the NIST-standardised post-quantum key encapsulation algorithm (FIPS 203), paired with AES-256-GCM for the message itself. Archives harvested today stay sealed against future computers.
Identity before unsealing
A recipient proves who they are (via bank credentials through the Finnish Trust Network, a one-time SMS code, or an agreed PIN) before any key is released to their browser.
Access is revocable
Expiry, view-once and withdrawal all take effect because we can withhold our half of the key. We still can't read the message.
Honest about the split
Why we hold half of the key.
Messages are end-to-end encrypted. The key needed to decrypt one is split in two, and we are specific about what we do with our half.
Your message key never reaches us in full
The message is sealed on your device with a key we never possess complete. Neither half opens anything alone.
Our half of the key is what makes withdrawal possible
We hold one half of the key and release it only after the recipient has verified who they are. That is why you can withdraw a message, set an expiry, or allow it to be opened only once. Our half cannot open anything on its own, so we cannot read your message.
Unsealing takes a moment on purpose
Every unlock runs an intentionally expensive calculation (Argon2) on the recipient's device, so nobody holding the sealed file can grind through guesses. The pause is a lock working, not a page hanging.
When an authority demands data
We can be compelled to hand over what we hold: sealed data and delivery metadata. We hold no means of opening your messages, so there is nothing readable to produce. We'd publish what we receive.
Where your data lives
Under Finnish law,
on servers in Finland.
Message content and encryption keys are stored on servers in Finland, operated under Finnish and EU law. Jurisdiction follows who owns the provider, not only where the racks sit.
Data centre
Our servers are in Hetzner Finland Oy's data centre in Tuusula, Finland. Hetzner only runs the data centre. It cannot read message content, because messages are sealed on the sender's device before they arrive.
Legal entity
Suoja Email Finland Ltd (Suoja Email Finland Oy), a Finnish limited company (business ID 3658119-3(opens in a new tab)), domiciled in Ulvila, Finland.
Report a vulnerability
Write to security@suoja.email. We will respond within two working days.
Control after sending
Withdraw
Pull access and the message stops opening for everyone, immediately.
Expiry
A lifetime in hours or days. When it lapses, it stops opening on its own.
View once
It unseals a single time, and then it's done.
Reviewing us for your organisation?
We're happy to walk a security or procurement team through the architecture in detail.