Verify an Anchor Proof

What this site is

This site is a reference implementation of the Anchoring Specification (IEC). It performs independent verification of anchoring proofs.

It does not create anchors.
It does not issue certificates.
It does not provide commercial services.

Verification Model

Verification is defined by the Anchoring Specification as:

V(B, P, L) → { valid | invalid | unverifiable }

Where:
B = the exact byte sequence of the artifact
P = the proof bundle (certificate and optional ledger proof)
L = publicly verifiable ledger infrastructure

This verifier implements that function.

What this verifier establishes

If verification returns valid, exactly one property is established:

These exact bytes existed on or before time T.

Where T is derived from publicly verifiable ledger consensus. No additional claims are implied.

What this verifier does not establish

Verification does not establish: authorship · ownership · originality · legal validity · identity · intent · truthfulness.

It establishes existence-at-or-before-T only.

Output Semantics

The verifier returns exactly one of:

valid — hash integrity confirmed and ledger proof verified
invalid — hash mismatch or ledger proof invalid
unverifiable — verification cannot be completed (e.g. missing artifact, missing ledger proof, network unavailable)

No other interpretation is permitted.

Independence

This verifier makes zero API calls to Umarise, anchoring.app, or itexisted.app. It requires no account. It requires no login. It stores no data. It depends on no backend infrastructure.

Verification remains possible without the issuer of the proof. After a proof is created, no ongoing relationship with the issuing service is required for verification.

The source code is public and may be forked or self-hosted by any party.

Specification

This verifier implements the Anchoring Specification (IEC v1.0). The specification defines the verification function, the permitted outputs, the semantic scope of anchoring, the exclusion of non-chronological claims, and ledger qualification requirements.

The specification is normative. This implementation is not.

CLI Verification

Verification may also be performed using compatible CLI tools. Any tool capable of computing SHA-256 and verifying OpenTimestamps proofs against the Bitcoin blockchain can independently validate an anchoring proof.

Example: ots verify certificate.ots (OpenTimestamps CLI)

Verification Scope

This reference verifier performs: hash match, ZIP/certificate parsing, OTS header validation, and .ots download. It does not perform full Bitcoin verification in v1 — use ots verify or opentimestamps.org for ledger confirmation.

For registry lookups and proof status via Umarise infrastructure, visit umarise.com/verify. That verifier provides value-added context but depends on issuer infrastructure.