[OVAIC interop] Independent check: FURUI day record 2026-11-04, ledger entry 254, Bitcoin block 974714

[consortium at ovaic.org]

> Hello all,
> 
> Second independent check on this list: the FURUI day record for 2026-11-04 from The HORIZONs Co., Ltd., and its Bitcoin anchor. Same method as for 2026-11-03, our own code (Python, PyNaCl, the opentimestamps library), not the publisher's verifier.
> 
> Record: https://ledger.horizonshield.dev/furui-check-day/6f5e159978013f77515097a0efc3cc138303392b15b91105ee0aaa7c3a346f47
> Ledger entry: https://ledger.horizonshield.dev/ledger/254
> Proof: https://ledger.horizonshield.dev/ledger/254/ots
> Key: https://ledger.horizonshield.dev/.well-known/furui-check-keys.json
> 
> 1. Record bytes. SHA-256 of record_canonical = 6f5e159978013f77515097a0efc3cc138303392b15b91105ee0aaa7c3a346f47, equal to the name in the URL. The record states day 2026-11-04, n = 2, root 88e0315b092d0110147d222def0b28fba6fc1d5688ef37eaf76c1f13dd7ec4cc (RFC 6962, SHA-256).
> 2. Signature. Ed25519 by key runner-1 verifies over "furui-check-day-v0\n" followed by the canonical JSON of the record without its signatures field. Result: valid.
> 3. Batch. The raw bytes of ledger entry 254 (nenrin-agreement-batch-v1, 3 records) hash to c0e5a93d23ba74cdcd0859a1d2044a3c83f113e0d9768d60f9423234133da903, and the list contains the day record hash above.
> 4. Anchor. The OpenTimestamps proof commits to exactly that digest and ends in two Bitcoin block header attestations. The computed Merkle roots equal those served by a public explorer (Blockstream):
>    block 974714 (2026-11-05 21:41:15 UTC): 1a521a5eb5db7c2c88ee87730fd4cac18b8eb2a69848507f13fcbf351f22b7fa
>    block 974715 (2026-11-05 21:46:26 UTC): 975d44ea9f6c1c0dd3574b280d7edd34dd23807861f769ef11d5b28e80a13e87
>    The earlier one, 974714, is the bound.
> 
> Result: the record is unaltered, signed by the key the ledger serves, included in batch entry 254, and that batch existed no later than Bitcoin block 974714.
> 
> One observation for readers. The publisher notes that this batch was cut by hand ("anchored_by": "operator"). That field is in the ledger's metadata for the entry (?format=json), not in the batch bytes, so the Bitcoin anchor does not cover it. The time "anchored_at" (2026-11-05 21:10 UTC) is inside the bytes and is covered. Neither point changes the result above.
> 
> Limits as before: nothing behind the root is checked (only the runner holds the leaves), the anchor bounds time from above and settles nothing else, and the block headers come from one explorer; a check against your own Bitcoin node is stronger.
> 
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> 
> With warm regards,
> Alexander Neumann & OVAIC Team
> Open Verifiable AI Consortium, Zurich · https://ovaic.org
> Agora, the open laboratory for checking claims · https://agoranet.work
> consortium at ovaic.org
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