# A Bitcoin Anchor


Bitcoin timestamp for a hash, for under a cent.

## At a glance

- **Attests:** Nothing directly on the record. Two independent bindings do the work: the purchase certificate signs the buyer's digest via its attests field, and the OpenTimestamps proof commits the same digest into a Bitcoin transaction — the store's dated word and Bitcoin's clock, separately checkable.
- **Input:** digest (query parameters; input schema and checkout: https://scvd.store/menu/bitcoin_anchor?view=compact)
- **Output:** A signed certificate binding the buyer's sha256 digest in its attests field, plus a stable proof URL serving the OpenTimestamps proof bytes — pending on purchase, upgrading automatically to a Bitcoin-confirmed proof verifiable with the standard ots tool against block headers alone. Instant; one digest, one submission, nothing recurs. Every artifact carries a cert_id and verifies free at https://scvd.store/api/verify/{cert_id}.
- **Cryptography:** ed25519 signature by this store's key, published at https://scvd.store/.well-known/scvd-signing-key and carried inside every 402
- **Verify:** GET https://scvd.store/api/verify/{cert_id} — free, no account, no rate limit, checkable offline with the published key
- **Price and fulfilment:** $1 USDC fixed, one-off; nothing here charges again by itself, ever — there is no mechanism that could; delivered instantly
- **Does not attest:** What the digest is a digest OF. The label is the buyer's own claim, stored verbatim and never checked; the proof establishes the digest existed by a Bitcoin block, nothing about the bytes behind it.

## About this item

Give us a sha256 digest — of your key log, your dataset snapshot, anything you canonicalize yourself — and we submit it to OpenTimestamps, which commits it into a Bitcoin transaction. You get a signed certificate binding your digest, and a stable proof URL that serves the OTS proof bytes: pending within the hour, typically Bitcoin-confirmed within a few, upgradeable forever after. What that proves, exactly: the digest existed by that Bitcoin block, on evidence that is not ours and not yours. We never see what the digest is of, we do not interpret the label you attach, and one purchase anchors one digest once — no monitoring, no re-anchoring, no schedule.

- **id:** `bitcoin_anchor`
- **price:** $1 fixed, one-off; nothing here charges again by itself, ever — there is no mechanism that could
- **fulfillment:** delivered instantly
- **buy:** `GET https://scvd.store/api/buy/bitcoin_anchor?digest=<digest>` (USDC over x402 v2 on Base, Polygon, Arbitrum, World, Solana, Arc (Circle Gateway), or USDC over MPP (evm/charge) on Base for every shelf item, every publication page and the commission desk)
- **required inputs:** `digest` — fill the `<digest>` slot above before paying. The bare door `GET https://scvd.store/api/buy/bitcoin_anchor` quotes free and refuses the paid request without it; no money moves.
- **sample:** https://scvd.store/samples/bitcoin-anchor.json
- **does not prove:** What the digest is a digest OF. The label is the buyer's own claim, stored verbatim and never checked; the proof establishes the digest existed by a Bitcoin block, nothing about the bytes behind it.

House rules: give the digest in the digest query parameter: 64 hex characters, a sha256 you computed over bytes you keep; optional label query parameter, up to 120 characters, stored verbatim as your claim about what the digest covers — never checked, never interpreted; one digest, one submission, one proof url; nothing recurs; the proof upgrades to bitcoin-confirmed on our next passes automatically; the certificate is yours from the moment of purchase either way.

> A dollar to nail your digest to a clock nobody owns. We never see what's behind it, and once it's in, it's past us.