Frequently Asked Questions

BlockProve is a digital evidence certification app. Take a photo, film, record or deposit a file: BlockProve establishes its existence, integrity and date, verifiable by anyone, through a cryptographic fingerprint (SHA-256), a post-quantum signature (ML-DSA-87), an eIDAS qualified time-stamp and permanent anchoring on the Arweave blockchain. Your files are encrypted on your device before anything is sent: BlockProve never has access to them. A PDF report and a PCAP container let you present your proofs and have them verified by a third party.

Each file is associated with a cryptographic fingerprint (SHA-256 hash) computed locally on your device. This fingerprint, along with a timestamp and post-quantum signature, is engraved on the Arweave blockchain. Any modification to the original file would produce a different hash, making falsification mathematically detectable.

No, never. BlockProve is built on zero-access, end-to-end encryption: AES-256-GCM encryption runs entirely on your device before any upload. Our servers only receive unreadable data blocks. Even BlockProve's own team is technically unable to access the content of your files.

Yes. BlockProve is available on Windows, macOS, iOS (iPhone and iPad) and Android. Certified capture of photos, videos and audio recordings is available on mobile; file deposits and proof verification on every platform. Deposits go through our servers, which only receive data encrypted on your device. Once anchored on the Arweave blockchain, your proofs remain verifiable by anyone without BlockProve: the PCAP container and its open-source verifier are enough, even if BlockProve ceased to exist.

Under French law, evidence of a fact may be produced by any means (Article 1358 of the Civil Code): digital evidence such as a BlockProve proof is admissible in court, and the judge assesses its probative value. Example: in a judgment of 20 March 2025, the Marseille Judicial Court (AZ Factory v. Valeria Moda) relied on the time-stamping of designs on a public blockchain, corroborated by a bailiff's report, to recognise the fashion house's copyright and sanction the counterfeiting. This first-instance decision illustrates the admissibility of this type of evidence, without being a guarantee for every dispute. BlockProve proofs add an electronic qualified time-stamp within the meaning of the European eIDAS regulation, which enjoys throughout the European Union a presumption of the accuracy of the date and time it indicates (Article 41).

A sufficiently powerful quantum computer will be able to break classical cryptographic signatures (RSA, ECDSA). BlockProve signs every proof with ML-DSA-87, derived from CRYSTALS-Dilithium: the post-quantum signature algorithm standardised by NIST (FIPS 204), in its highest security variant. Your signatures thus remain secure and verifiable, even against tomorrow's quantum computers.

In the app, open "Help & support" then "Report a problem": the app version, platform and language are attached automatically, which speeds up the diagnosis. You can also use the contact form on the website or write to contact@blockprove.me. Our team replies within 24 to 48 business hours.

Each proof shows the assurance level verified by our servers when it is anchored. N1, standard proof: SHA-256 fingerprint of your files, post-quantum signature and anchoring on the Arweave blockchain; it establishes that a content existed, unaltered, at a given date. N2, hardware-attested capture: the photo, video or recording is sealed at capture time by a non-extractable hardware key of the device (Secure Enclave on iPhone, StrongBox or TEE on Android), and our server checks with Apple or Google that this key belongs to a genuine device and to the BlockProve app; the capture conditions are thus attested. N3, verified identity and qualified time-stamp: level N2 plus a verified identity and an eIDAS qualified time-stamp; this level is in preparation. When a capture remains at level N1 (device without hardware attestation, simulated GPS location, etc.), the PDF report states the reason.

PCAP (Proof of Capture) is the open format in which BlockProve exports your proofs: a single container, the .pcapc file, that gathers the fingerprint of your files, the post-quantum signature, the reference of the Arweave anchoring, the RFC 3161 time-stamp token and, for an attested capture, the device's hardware seal. The container itself is signed (COSE, ML-DSA-87). Its specification and a verifier are published as open source: a lawyer, a court expert or a judge can verify a proof without relying on BlockProve or its servers, even if BlockProve were to disappear. By default, the container reveals neither your files nor the capture location: these data are only included if you choose to disclose them.

In addition to blockchain anchoring, BlockProve has each proof time-stamped by a qualified trust service provider within the meaning of the European eIDAS regulation (No 910/2014), following the RFC 3161 standard. A qualified electronic time-stamp enjoys, throughout the European Union, a presumption of the accuracy of the date and time it indicates and of the integrity of the data to which they are bound (Article 41). The token covers the fingerprint of your proof; it is included in the PDF report and in the PCAP container. If the provider is temporarily unavailable, the proof is still anchored and the qualified time-stamp is added automatically as soon as possible. The report always states whether the time-stamp is qualified.

A workspace lets a team (law firm, company, family) share proofs without ever exposing them to BlockProve. Each workspace has its own encryption key, generated on its creator's device; it is given to each member encrypted with that member's personal key, derived from their recovery phrase, so our servers never see it in clear. To invite someone, you send them a time-limited invitation code, of which only the fingerprint is stored. Roles (owner, administrator, member, viewer) determine who can deposit, invite or administer. When a member is removed, the workspace key is renewed: they cannot read proofs deposited afterwards. Every action is recorded in an encrypted, unalterable audit log, displayed in each member's language.

It means that BlockProve cannot know the content of your proofs. Your files, titles, descriptions, folders and workspaces are encrypted (AES-256-GCM) on your device before anything is sent, with keys derived from your recovery phrase, which never leaves your device. Our servers only keep encrypted data and fingerprints: they cannot decrypt them, including at the request of a third party. This is a zero-access architecture; it does not rely on zero-knowledge proofs in the cryptographic sense, which the PCAP protocol plans to integrate for selective disclosure. The trade-off: if you lose your recovery phrase, no one can recover your encrypted data.

When depositing, you choose what is written on the Arweave blockchain. Full archive: your encrypted archive (files and metadata) is itself anchored on Arweave together with the proof. Strengths: permanent, decentralised storage, independent of BlockProve; you will always be able to retrieve and decrypt your files with your recovery phrase. Limits: this storage is final and can never be erased, even though it stays encrypted; it costs 1 BPV credit per 30 MB started. Proof only: only the proof (SHA-256 fingerprint, post-quantum signature, time-stamp) is anchored on Arweave; your encrypted archive is kept in our backup vault. Strengths: 1 BPV credit whatever the size, and nothing but the proof is written permanently. Limits: the archive's availability depends on BlockProve; keep a copy of your original files. In both cases, the anchored proof remains verifiable permanently: it establishes that an identical file existed at the stated date.

Your 12-word recovery phrase is the only key to your data: it is created on your device and BlockProve does not know it. Keep it on paper, in a safe place. When reinstalling or on a new device, import that same phrase: the app checks that it is your account's phrase, then restores your backed-up proofs and workspaces. If you have lost it, no one, not even BlockProve, can decrypt your backups; you can create a new identity for your future deposits, and your already anchored proofs remain publicly verifiable.