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 file or text is displayed on your ProofSeal proof page for transparency or disclosure; 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