Prove a document existed and was signed at a point in time — without ever revealing the document. Post-quantum ready, and verifiable by anyone against Bitcoin block headers alone.
The service never sees your file and never touches your keys.
You hash your document and sign the hash on your own device. Only the hash, signature, and public key are sent — never the content.
The service verifies the signature and writes a canonical proof to a BSV OP_RETURN, returning a self-contained certificate.
Anyone re-checks the signature offline and confirms the anchor against Bitcoin block headers — no provider, no database, no trust in us.
The document and your private key never leave your machine. We physically cannot leak what we never receive.
Classical ECDSA plus ML-DSA (FIPS 204) and SLH-DSA (FIPS 205) — 16 signature algorithms, so proofs survive the quantum transition.
Certificates carry an SPV proof. Verify the anchor against block headers alone — the chain is the trust anchor, not our server.
Many proofs anchor under a single transaction via an RFC 6962 Merkle root, driving per-proof cost toward zero at volume.
The integrity root is a fixed, length-prefixed binary encoding — never JSON — so any implementation in any language reproduces identical bytes.
The proof-of-existence time is the Bitcoin block time of the anchoring transaction, not a server clock.
Paste a NotaryHash certificate to check it now. Certificates with an SPV envelope are verified against Bitcoin block headers.
REST endpoints with OpenAPI docs at /docs. Verification is open to everyone; anchoring requires an API key. You sign locally — only the hash, signature, and public key are ever sent.
# Supported algorithms (classical + post-quantum)
curl https://notaryhash.com/v1/algorithms
# Verify a certificate — offline checks + SPV anchor against block headers
curl -X POST https://notaryhash.com/v1/verify \
-H 'Content-Type: application/json' \
-d '{ "certificate": { /* paste a certificate */ } }'
# Anchor a signed hash (needs X-API-Key; the document never leaves your machine)
curl -X POST https://notaryhash.com/v1/notarize \
-H 'Content-Type: application/json' -H 'X-API-Key: YOUR_KEY' \
-d '{ "algorithm": "ECDSA-secp256k1", "payloadHash": "<sha256-hex>",
"publicKey": "<hex>", "signature": "<hex>" }'
NotaryHash is part of SmartLedger's post-quantum blockchain, identity, and AI stack for enterprise and government.
Blockchain notarization for records and audit trails.
Air-gapped, post-quantum hashchain for governments and enterprises — append-only, tamper-evident, ML-DSA-signed, with node replication.
Post-quantum-ready attestation for public institutions.
Auditable agentic AI with provenance tracking.
Notarized media creation with IP protection.