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03 · SHA-256 · Proof of existence

File Certification

Tamper-proof evidence that a file existed, and who owned it, on a given date.

Open app · certificar.centroblockchain.com

We record your file's digital fingerprint (hash) on Ethereum. Anyone can later verify that the document hasn't changed by a single bit since that moment.

What’s included

  • Immutable on-chain timestamp
  • Permanent proof of authorship
  • Publicly verifiable by third parties
  • Works with any file type

Field-by-field guide

  1. 01

    File

    Select the document you want to certify.

    Tip: Any format works: PDF, image, audio, video…

  2. 02

    Title

    A descriptive name for the certificate.

    Tip: E.g. “Lease agreement – Unit 4B – 2026”.

  3. 03

    Description

    Context for the file: author, date, license.

    Tip: The more precise, the more useful as evidence.

  4. 04

    Network

    Sepolia to test; Ethereum for the definitive certificate.

    Tip: Only certification on Ethereum counts as a real record.

You'll receive a unique hash proving the file existed on that date. Keep the original file untouched: it's what allows the match to be checked.

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