{
  "height": 16,
  "block_hash": "550d7c29735d4760a6a2ca798a688c005f925bb4d94fedf379925c1471472595",
  "status": "confirmed",
  "bitcoin_block_height": 974874,
  "digest": {
    "alg": "sha256",
    "hex": "550d7c29735d4760a6a2ca798a688c005f925bb4d94fedf379925c1471472595",
    "preimage": "block:{\"at\":\"2026-11-06T23:28:33.666Z\",\"entry_count\":2,\"first_seq\":77,\"height\":16,\"key_id\":\"key_a521921c2ba20669\",\"last_seq\":78,\"merkle_root\":\"1d3afbe36c7516638c08eb81091603eaff78cec00ffd8f9723d28849906b9800\",\"prev_hash\":\"5a59150baff15e47a5804a9223b813a5a285bb144fb084f194cfb290a5ac2889\",\"v\":1}"
  },
  "calendars": [
    {
      "calendar": "https://a.pool.opentimestamps.org",
      "status": "confirmed",
      "submitted_at": "2026-11-06T23:33:03.603Z",
      "updated_at": "2026-11-07T02:38:43.467Z",
      "bitcoin_block_height": 974874,
      "attestations": [
        {
          "type": "pending",
          "uri": "https://alice.btc.calendar.opentimestamps.org",
          "commitment": "6aee63b0c6a47852c613ad6073db58fc2f51fbbca15af1cae749fee9207c5dcc95fb7dbde2e7ad628aee0a9d"
        },
        {
          "type": "bitcoin",
          "block_height": 974874,
          "merkle_root": "fa522f272a37cb03554d5be30f11a1564362627a0d248c198befb5a303c3a302"
        }
      ]
    },
    {
      "calendar": "https://b.pool.opentimestamps.org",
      "status": "confirmed",
      "submitted_at": "2026-11-06T23:33:03.603Z",
      "updated_at": "2026-11-07T03:38:43.477Z",
      "bitcoin_block_height": 974877,
      "attestations": [
        {
          "type": "pending",
          "uri": "https://bob.btc.calendar.opentimestamps.org",
          "commitment": "6aee63b17c3357bb8569cadff032963c49e264a9f684b728e47dcc1cbbf00ea0ded1f26fa272567cd0325031"
        },
        {
          "type": "bitcoin",
          "block_height": 974877,
          "merkle_root": "dee625f48434576e86df10e80f2912b1c31b96672232e47e103806c1faef5814"
        }
      ]
    },
    {
      "calendar": "https://finney.calendar.eternitywall.com",
      "status": "confirmed",
      "submitted_at": "2026-11-06T23:33:03.603Z",
      "updated_at": "2026-11-07T03:38:43.477Z",
      "bitcoin_block_height": 974877,
      "attestations": [
        {
          "type": "pending",
          "uri": "https://finney.calendar.eternitywall.com",
          "commitment": "6aee63b071ebf8ca3ff3f088f02d85b607b2fa50f752ee2a3d0779b3a50b0f147440e76378e58fcbb5394326"
        },
        {
          "type": "bitcoin",
          "block_height": 974877,
          "merkle_root": "dee625f48434576e86df10e80f2912b1c31b96672232e47e103806c1faef5814"
        }
      ]
    }
  ],
  "proof_url": "https://www.a2ally.com/v1/ledger/blocks/16/anchor.ots",
  "how_to_verify": "Download the .ots proof and run `ots verify -d <block_hash> <file>.ots` with the OpenTimestamps client, which checks the Bitcoin attestation against Bitcoin block headers. The digest is the block hash: sha256 of digest.preimage, the text \"block:\" followed by the canonical block header, which is the same header the issuer signs."
}