How OpenTimestamps anchoring works
- Every ~5 minutes, the substrate's cron computes the current L12 HEAD hash for each chain.
- The hash is submitted to OpenTimestamps calendar servers (alice.btc.calendar.opentimestamps.org and peers). Calendars aggregate submissions into a Merkle tree.
- Within ~1 hour, the Merkle root is committed to Bitcoin as one transaction. Subsequent OTS upgrade calls add the Bitcoin path to the local .ots proof file.
- After 6 confirmations (~1 hour additional), the proof is "complete" — verifiable offline against any Bitcoin full node, no calendar trust required.
Backdating past the most recent anchor block becomes provably impossible — that's the property regulators care about.