PS
ProofSeal

Why Bitcoin Anchoring Is Secure

The cryptographic and economic foundations behind ProofSeal

Trust Model (at a glance)
What you must (and must not) trust

You don’t need to trust us

  • • Hash is computed client‑side or verifiably provided
  • • Only the 32‑byte SHA‑256 hash is stored on‑chain (no data, no secrets)
  • • Anyone can independently verify with public tools or their own node

What you rely on

  • • SHA‑256 security (pre‑image & collision resistance)
  • • Bitcoin’s finality (confirmations) and immutability
  • • Correctly following the verification steps
Cryptographic Guarantees
Why a hash is a reliable fingerprint
  • Pre‑image resistance: Given the hash, finding any input that produces it is computationally infeasible.
  • Second pre‑image resistance: Given a document, finding a different document with the same hash is infeasible.
  • Collision resistance: Finding any two different documents with the same hash is infeasible.

We use SHA‑256, the same hash function securing Bitcoin itself.

Timestamp & Finality
Anchored in a global, append‑only ledger
  • Global ordering: Your hash is embedded in a Bitcoin transaction (OP_RETURN). The block height anchors it to a specific point in time.
  • Confirmations: Each block after yours increases the cost of rewriting history. We consider 3+ confirmations as “final” for most uses.
  • Public verifiability: Anyone can fetch the transaction and inspect the OP_RETURN to compare with your calculated hash.
Privacy by Design
Prove existence without revealing the content
  • Private mode: Your data never leaves your device; only the hash is anchored.
  • Public mode: Your text is displayed on your ProofSeal proof page for transparency; the on‑chain commitment is still just the hash.
  • Minimal on‑chain data: We commit only a 32‑byte hash — no headers, metadata, or IDs.
Threat Model & Limits
What this proof guarantees — and what it doesn’t
  • Proof of existence: Demonstrates your document existed no later than the timestamped block.
  • Immutability: A differing document will not reproduce the same hash (cryptographic hardness).
  • Chain reorgs: Extremely rare at high confirmations; we surface confirmations so you can choose your policy.
  • Content secrecy: Private mode protects plaintext; disclosure is always your choice.
  • Identity & authorship: Out of scope for hash‑anchoring; combine with signatures if required.
Independent Verification
Anyone can check your proof with public tools
  1. Recreate the SHA‑256 hash of your text/file (our certificate includes the exact steps).
  2. Open the transaction on a Bitcoin explorer and find the OP_RETURN output.
  3. Confirm the OP_RETURN payload (hex) equals your 64‑character hash.
Why Use ProofSeal
Security without complexity
  • Fast: One click, one transaction, permanent record.
  • Professional: Plain‑language certificate, legal‑friendly format.
  • Private‑by‑default: Client‑side hashing, minimal on‑chain footprint.
  • Independently verifiable: Works with public explorers and your own node.