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THE REFERENCE IMPLEMENTATION OF C2PA

Sign, resolve, and verify C2PA at protocol scale.

Sign C2PA manifests, resolve them across re-encodes and crops, and verify cryptographic integrity. One HTTP API.

C2PA 2.1ISO 22144JUMBFCOSEEd25519ML-DSA-65SHA-256MerkleIPFS CIDv1

Sign, Resolve, and Verify

MANAGED SIGNING & STORAGE

Sign C2PA manifests at any volume.

Hashproof issues signed C2PA manifests with managed keys, Merkle-anchored proofs, and pHash indexing. Every signed asset is stored with its content-address CID and a verifiable inclusion proof.

  • COSE / Ed25519 + ML-DSA-65 hybrid
  • Merkle-anchored to Base L2
  • IPFS CIDv1 storage
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SOFT-BINDING LOOKUP

Find the manifest after re-encodes and crops.

pHash-based resolution keeps provenance anchored through platform transformations. Hamming-distance thresholds are configurable; the API returns ranked candidates with similarity scores.

  • 2D-DCT perceptual hashing
  • 10-bit Hamming threshold default
  • Multi-candidate response shape
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CRYPTOGRAPHIC PROOF

Confirm authenticity in one call.

Upload a binary to the verify endpoint. Hashproof returns C2PA chain validation, signature check, trust-list matching, and manifest lineage, plus a structured trust-status field ready to render.

  • Signature + chain check
  • Trust-list match
  • Lineage DAG response
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Federation and compliance

TRUST FEDERATION

Verify across federated registrars.

Connect to peer registrars over mutual TLS and verify against the union of their trust lists. Cascading verification fetches upstream lineage, so provenance stays intact across registrar boundaries.

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COMPLIANCE REPORTING

Generate EU AI Act disclosures.

Turn a signed corpus into EU AI Act Article 50 disclosures. Every claim links back to a manifest, signature, and Merkle inclusion proof, exported as auditor-ready PDF and JSON.

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PublisherHashproofSign · ResolveVerifyConsumer
verify.ts
import { HashproofClient } from '@hashproof/sdk';

const hp = new HashproofClient({ apiKey: 'hpsk_...' });

const result = await hp.verify(photo);
console.log(result.trustStatus);
// → "trusted"
terminal
npm install @hashproof/sdk
# or
pnpm add @hashproof/sdk

EU AI Act Article 50 requires synthetic-media disclosure starting August 2026.

The C2PA specification reached 2.1 in 2025. Hashproof implements every section, served as one HTTP API.

Wire it in before your next privacy review.

The reference implementation of C2PA. Served as one HTTP API.