Your questions.
Verifiable answers.

No. Fingerprints are computed locally, in your browser. The original file is never sent to DfinA Vault: we therefore cannot read it, keep it or disclose it.

No. DfinA Vault is designed to work without a mandatory account. You can keep, on your own device, a local history of your certificates. This history does not constitute remote storage of your files.

Every certification, whether per-unit or by subscription, always provides a SHA-256 fingerprint and a SHA3-512 fingerprint.

These two functions rely on different cryptographic designs and produce fingerprints of different lengths. This diversification does not mean that the protections mechanically "add up"; above all, it reduces reliance on a single algorithm and improves the robustness of the proof over time.

It makes it possible to demonstrate that a file presented later has exactly the same content as the one that was certified. The certificate links its fingerprints to a date and, when a seal is applied, to a declared origin.

Certification does not judge the content: it does not prove that a statement is true, that a document is legal, or that its holder is its rightful legal owner.

It is a technical piece of evidence, verifiable and reproducible, that can be presented in a case file. Its value depends on the context, the quality of the chain of custody and the assessment of the competent authority.

DfinA Vault does not replace a notarial deed, a judicial officer's report, or a qualified electronic signature.

Not on its own. It proves the integrity of the file and its presence in the proof system on a given date.

To claim continuity of origin, you can apply your DfinA Vault seal. An earlier timestamp, a publicly claimed seal and the ability to meet a signature challenge then form a stronger body of evidence.

Yes. Certification applies to the binary content, not to the file name. A strictly identical copy remains verifiable even if it has been renamed, moved or copied to another medium.

The slightest change to the content produces new fingerprints. An image edit, a change in a PDF, a new video compression or even a variation invisible to the eye can therefore make the file different from the certified original.

This is precisely what makes it possible to detect that a document is no longer identical, byte for byte.

Open the Verify page, then select the file you received or use the certificate's QR code. Fingerprints are recomputed locally and compared with those in the proof.

The verified file is not sent to DfinA Vault.

Yes. Batch verification lets you select several files and check in a single pass which ones match the available certificates. The result immediately distinguishes matches, modified files and files with no associated proof.

Yes, with the plans that include the advanced features. You select a set of files; DfinA Vault computes their two fingerprints locally and prepares the certificates without requiring a repeated manual operation for each document.

It gathers the useful documents into a single portable folder: certificates, proofs, summary and user guide. A single button thus lets you prepare a coherent archive to keep or to share.

The archive brings together the files and proof elements you have selected, in a coherent set that is ready to keep or to share.

DfinA Vault is a PWA. On Android or a computer, open the browser menu then choose Install app or Add to Home screen. On iPhone or iPad, use Safari's Share button, then Add to Home Screen.

Once installed, the app opens from its icon, like a regular application.

Yes. From the PWA or the mobile browser, the file picker can give direct access to the camera. You can therefore capture an item and certify it immediately, without a complex intermediate step.

The seal is a personal digital stamp, created from a secret phrase. Applied to your certificates, it lets you link a series of files to the same declared origin.

It answers the question "by which entity was this file sealed?", without requiring DfinA to know your civil identity. Discover how the seal works.

No. It contains no civil-status data. It proves the continuity of the same stamp and the holder's ability to reproduce it or to meet a signature challenge.

Its association with you is built by claiming it publicly on your website, your profiles or your communications.

There is no recovery procedure: DfinA does not know your phrase and cannot reset it. Seals already applied remain verifiable, but you will no longer be able to reproduce the same stamp.

Keep this phrase offline, in a safe and lasting location.

A visible image can always be copied. However, copying the image does not give cryptographic control of the seal.

The signature challenge makes it possible to distinguish the true holder of the seal phrase from someone who has merely reproduced its appearance.

No. Since the second version of the seal, this text is signed at the same time as the fingerprint. Any later change, even of a single character, makes verification fail.

The verifier shows it in green when it is covered by the signature, and in grey when it is not, which is the case for seals affixed before that version. Those remain perfectly valid.

One useful point: DfinA attests that this text has not changed since it was affixed, not that it is true. Whoever seals remains free in what they write there.

Essential immediately provides the DfinA Vault integrity proof, with both the SHA-256 and SHA3-512 fingerprints, as well as a date attested by DfinA and digitally signed: the precise timestamp, the certificate number and the fingerprint are sealed together and can no longer be altered afterwards.

Premium adds a second, independent temporal assurance: the SHA-256 fingerprint is embedded in an OpenTimestamps proof then anchored in the Bitcoin blockchain. Premium is therefore not necessary for every use; it strengthens cases where the independence and durability of the date are decisive.

No. You have no wallet to create and no digital asset to buy. DfinA Vault uses only the Bitcoin blockchain as a public timestamping infrastructure. You pay for the service in your usual currency, at a defined price.

Your certificate and your fingerprints remain usable. For a Premium proof, also keep the .ots proof file: it relies on an open standard and can be verified independently of DfinA Vault.

The most durable verification naturally assumes that you keep the original file, its certificate and the associated proof elements.

The certificate and the two fingerprints are generated immediately after the local processing of the file.

For Premium, anchoring in the Bitcoin blockchain follows. The OpenTimestamps proof can evolve and consolidate over the following hours; it then attests that the fingerprint existed at the latest at the moment of the confirmed anchoring.

Premium anchoring does not publish your file, its name or your identity. It records only a non-reversible cryptographic fingerprint, embedded in an aggregated proof.

Because DfinA Vault is designed without storing the original file, it does not hold that content to be erased. Any payment data is handled separately by the payment provider in accordance with its obligations.

Payment is processed by Paddle, which acts as Merchant of Record: it collects the payment, handles invoicing and applies the taxes corresponding to the transaction. DfinA Vault does not receive your full bank card number.

The conditions depend on the state of execution of the service and the rules applicable to your purchase. A certification that has already been generated corresponds to a digital service that has been performed.

See the refund policy for the exact conditions and the procedure.