Cryptographic Timestamping

Prove your document
existed and was
signed — quantum-safe

Sign any document with ML-DSA (NIST FIPS-204) and receive a verifiable cryptographic certificate. Anyone can independently verify the signature — no need to trust PQCServer. Your document never leaves your browser.

✏️ Sign a document ✔️ Verify a certificate
How it works
Four steps. Fully verifiable.
01
📄
Select document

Upload any file — PDF, DOCX, image, ZIP. Or type text directly. The document stays in your browser.

02
🔢
Hash computed

Your browser computes a SHA-256 fingerprint of the document. This hash uniquely identifies the document content.

03
✏️
ML-DSA signature

The hash is signed with your ML-DSA private key — locally, in your browser. Only the signature is sent to PQCServer.

04
📜
Certificate issued

PQCServer records the hash, signature and UTC timestamp. You receive a shareable link and a JSON certificate to download.

Zero-knowledge proof: PQCServer never receives your document — only its SHA-256 hash and the ML-DSA signature. The certificate is mathematically verifiable by anyone, independently of PQCServer, using only the public key and the original document.
Certificate format
What a certificate looks like
{ "version": "1", "id": "ts_x7k2p9ab3f", "service": "PQCServer Cryptographic Timestamp", "document_hash": "a3f2c1e8d4b7...", "hash_algorithm": "SHA-256", "signature": "BASE64_MLSDA_SIG...", "public_key_dsa": "BASE64_PUBKEY...", "algorithm": "ML-DSA (NIST FIPS-204)", "signer_name": "Alice Smith", "filename": "contract_2026.pdf", "timestamp_utc": "2026-03-17T14:32:01Z", "verify_url": "https://pqcserver.com/verify.html?id=ts_x7k2p9ab3f", "note": "Verifiable without trusting PQCServer" }
✓ What the certificate proves
  • • A document with this exact SHA-256 hash existed
  • • At the recorded UTC timestamp
  • • And was signed by the holder of the ML-DSA private key
  • • Corresponding to the public key in the certificate
✗ What it does not prove
  • • Legal identity of the signer (no eIDAS KYC)
  • • Signer had legal capacity at time of signing
  • • Equivalence to qualified electronic signature
Use cases
Where it already works today
⚖️
Private contracts

Two parties agree to use ML-DSA signatures in their contract. Both sign and exchange certificates. Cryptographically binding if both parties accept the standard.

💻
Software releases

Sign binary releases, firmware, or code packages. Users verify the signature matches the published public key — proving authenticity and integrity.

📰
Journalistic evidence

Journalists sign documents and whistleblower material at collection time. The timestamp proves the document existed before a certain date, regardless of when it is published.

🔬
Research & IP

Sign research papers, datasets, or invention disclosures to establish priority. The cryptographic timestamp proves who had what knowledge at what time.

🏢
Internal approvals

Companies can use ML-DSA for internal document workflows — sign invoices, purchase orders, or HR documents without needing a qualified certificate authority.

🗃️
Audit trails

Sign log files, configuration snapshots, or database exports at regular intervals. Creates a tamper-evident record that can be verified years later.

Legal status
Honest about what this is

PQCServer certificates are cryptographically strong but are not yet qualified electronic signatures under eIDAS. Here is a transparent breakdown:

The road ahead: The EU eIDAS 2.0 regulation is in force. ETSI is actively working on post-quantum algorithm profiles for AdES signatures. ML-DSA is expected to be formally included in qualified signature standards by 2026–2027 — at which point PQCServer certificates will be upgradeable to full qualified status. Documents signed today will already have the cryptographic foundation.
Start signing today

Generate your ML-DSA keypair, sign your first document, and get a verifiable cryptographic certificate — free, no account required.

✏️ Sign a document 🔑 Get ML-DSA keys first ✔️ Verify a certificate