obscurHow it is built
Written for people who need to check before trusting. Everything here can be verified from outside — and the last section says how.
What crosses the network, and what doesn't
Detection, substitution with placeholders and restoration all happen on the device. Document text is never sent anywhere: there is no feature to upload it, and no endpoint in the service that would accept it.
Only three things leave the computer, none carrying document content: the licence check, the update check and — once only, when you enter your code — the workstation activation, which sends twelve digits derived from a local key, the operating system and the app version. Not the computer's name, which often contains a person's name. Unplug the network and the app keeps working — the most direct way to verify this.
Where the keys live
The mapping between placeholders and real values is encrypted with AES-256-GCM. The key lives in the system keychain (Windows Credential Manager, macOS Keychain, Secret Service on Linux) and never leaves the device. We hold no copy: if it is lost, encrypted documents on that computer cannot be recovered — not even by us.
When the keychain is unavailable — a service with no user session — the key falls back to a permission-restricted file, and the interface says so rather than hiding it: it is weaker protection, and whoever relies on it should know.
The licence verifies itself, without asking anyone
The licence certificate is signed with Ed25519. The public key ships inside the app; the private key stays under our exclusive control and is never handed to a partner — not even one reselling under their own brand.
In practice: the app verifies the licence on its own, without connecting. No server has to answer for you to work, and there is no list of who is working right now.
Three detection layers, with different guarantees
Checksum rules — tax code, VAT number, IBAN, card numbers: nothing is guessed, a check digit is verified.
Sector dictionaries and personal vocabulary — terms known for a profession, plus the ones you add.
Statistical name recognition — also runs locally, and offers no guarantee of form.
When two layers claim the same text, the one with a real verification wins. That is not an aesthetic preference: a VAT number with a valid check digit must not be overridden by a statistical guess.
The check before anything leaves
Before letting you copy or export, the app re-reads the protected text and looks for what might have slipped through — including data disguised with invisible characters or with letters that merely resemble the expected ones.
If that check cannot complete, the app does not let you copy, and says so. That is deliberate: a confirmation issued while the check was interrupted would be a confirmation we could not stand behind.
What ends up in our logs
Request identifier, method, path, status and duration. Never request bodies, not even truncated; never headers, which carry session cookies; never query parameters, which can carry email addresses. An automated test sends a sentinel string and fails if it reappears in the logs.
Passwords are stored with Argon2id. For session tokens and confirmation codes the database holds only the fingerprint, never the value.
What we deliberately do not do
There is no telemetry: we do not know how many documents you process, when, or of what kind. The website uses no analytics and sets no cookies.
There is no way for us to read your documents remotely, unlock a local key, or recover an encrypted archive. These are real limits, not wording: if you ask us to recover documents from a lost computer, the answer is that we cannot.
How to verify it yourself
- Unplug the network and use the app on a document: it keeps detecting, protecting and restoring.
- Watch the traffic with any tool you like while processing a document: you will see the licence and update checks, and no content being sent.
- Compare the SHA-256 fingerprint of the file you downloaded with the one published on the download page: if they match, the file is the one we built.
- Check the installer signature: on Windows from the file properties, on macOS the package is notarised by Apple.
If any of these checks does not add up, write to us: it is exactly the kind of report we want to receive.