Common questions, considered answers.

Does the file leave my machine?

No. The browser computes the file's SHA-256 and SHA-512 fingerprints locally and only those fingerprints are submitted. The SHA-256 is what the calendars commit to Bitcoin; the SHA-512 sibling is recorded in the receipt as cryptanalytic diversity and is not itself anchored. The file is never transmitted.

What does the receipt prove?

That a file with this fingerprint existed by the time of the recorded Bitcoin block. Nothing is claimed about authorship, ownership, originality, or content.

What if the file is renamed or modified later?

Any change to the file produces a different fingerprint and would not verify against the original receipt. The receipt attests to the exact bytes that were present at the time of anchoring; nothing more, nothing less.

Why Bitcoin?

Bitcoin has not reorganized beyond a handful of blocks in sixteen years. A block from an hour ago is, for any practical purpose, immutable. Orphograph commits to that chain via the OpenTimestamps protocol, which aggregates many fingerprints into a single transaction so the marginal cost per anchor is effectively zero.

How long does it take?

Calendar attestations are immediate; a receipt is issued within a few seconds in a pending status. The calendars aggregate fingerprints in batches, and commitment to a Bitcoin block typically confirms within a few hours, at which point the receipt progresses to pinned. The receipt remains valid throughout that interval; a second notice formalizes the on-chain commitment.

How is the receipt verified later?

Two tools, and it is worth knowing which does what. Our published one-hundred-line MIT verifier checks a receipt's structure offline: that each .ots proof is well-formed and commits to the receipt's hash. It makes no network call, so it does not itself consult Bitcoin. The OpenTimestamps client (ots verify) is what reads the chain and confirms the timestamp is in a block. Neither tool requires Orphograph; if this office were to close, every receipt remains independently checkable with both.

Can I anchor a Bitcoin transaction directly instead of using calendars?

A premium direct-transaction option is on the roadmap for cases where the standard one-block-window is unsuitable. For the common case, the OpenTimestamps aggregator path is more cost-efficient and equally final.

Will quantum computers break this proof?

No, on current cryptographic understanding. Shor's algorithm threatens signatures, not hash structures — and an OpenTimestamps proof is a chain of hash commitments with no signature in the proof path. Grover's algorithm leaves SHA-256 preimage resistance at roughly 2¹²⁸ quantum operations, far beyond feasibility; NIST treats SHA-2 as secure for hashing in a post-quantum setting. A future quantum computer could disrupt Bitcoin's future operation — signature migration, mining economics — but it cannot silently falsify past commitments; rewriting history would mean publicly out-working the accumulated chain. Receipts anchored through this website also carry a SHA-512 sibling fingerprint for cryptanalytic diversity on a scale of decades; the sibling is optional on the API, so a receipt created by another client may record SHA-256 alone. The sibling is recorded in the receipt, not committed to Bitcoin — the anchored commitment is the SHA-256. The math your receipt rests on is the part quantum computers are worst at.

What is recorded about me?

For free-tier visitors, only a truncated network address is retained for rate-limiting, and only briefly. For account-holders, the email used at sign-in and a non-reversible identifier derived from it. No file names, no content, no full network addresses, no behavioural profiles.

Is there an account requirement?

The free tier requires no account. Paid tiers use email-based sign-in for the receipt vault and unrestricted anchoring; no password is created or stored.

Does Orphograph attest that a file is human-made or not AI-generated?

No. The receipt records that a file existed at a given moment. Whether the file was created by a person, a model, or any other process is outside the scope of what is attested.

Can the receipt be used in court?

Orphograph issues no opinion on evidentiary admissibility. The receipt is a mathematical attestation that a fingerprint existed by a given block, verifiable against the public Bitcoin chain. How a given jurisdiction weighs that attestation is a matter for counsel.

What happens to the receipt if Orphograph closes?

Every receipt remains checkable without us: the published MIT verifier confirms the receipt's structure offline, and any OpenTimestamps client confirms the commitment against the Bitcoin chain itself. The receipt is the instrument; this office is the issuer, not the trust anchor.