ExistBefore

How the proof works

What ExistBefore does

ExistBefore creates cryptographic proof that a specific file or text existed at a specific time. It is public, free, and account-less, powered by the CertiSigma trust infrastructure.

  1. Hash on your device

    Your file or text stays in the browser. We compute SHA-256 locally. Nothing except the hash is transmitted.

  2. Register the fingerprint

    The 64-character hex hash goes through a server-side proxy that adds the API key. The CertiSigma API never sees your original content.

  3. Get your certificate

    You receive an immediate T0 signature, a PDF you can share, and a link to check T1 and T2 as they complete.

What crosses the network

The proxy injects the API key server-side; your browser never sees it.

Three layers of proof

Trust increases as asynchronous steps complete. The PDF and proof page show the current state.

T0 Digital signature Immediate

ECDSA P-256 over the attestation payload. Technical proof that CertiSigma registered this hash at this time.

T1 Qualified timestamp ~1 hour

Merkle batch + RFC 3161 TSA. Legal value under eIDAS (EU regulation).

T2 Bitcoin anchor 24–48 hours

OpenTimestamps → public blockchain. Long-term verifiability without relying on a single operator.

PDF and verification

The PDF is a human-readable container for the cryptographic data — not the root of trust itself. You can verify independently by recomputing the hash and checking the signature, or use the public API.

Read more: Digital timestamping, Proof of existence vs copyright, Technical overview.

Build this into your product

ExistBefore is powered by the CertiSigma API — the same endpoints are available for integration into legal tech, document management, and creative tools. API documentation →