{
  "height": 50,
  "block_hash": "8ba66840c7d113393b43837d34e9ef49786ec753a7f93f95c85fbbe19438409e",
  "status": "confirmed",
  "bitcoin_block_height": 974874,
  "digest": {
    "alg": "sha256",
    "hex": "8ba66840c7d113393b43837d34e9ef49786ec753a7f93f95c85fbbe19438409e",
    "preimage": "block:{\"at\":\"2026-11-07T01:12:00.021Z\",\"entry_count\":1,\"first_seq\":133,\"height\":50,\"key_id\":\"key_a521921c2ba20669\",\"last_seq\":133,\"merkle_root\":\"f16e80e11ca0b4749781e9a42936f9a282c8c314161cc2b1b933c9f76e65beb0\",\"prev_hash\":\"437975afe33df92552aef17ba0f1fa06089d0b9a13a556e79a2324d71b6577e8\",\"v\":1}"
  },
  "calendars": [
    {
      "calendar": "https://a.pool.opentimestamps.org",
      "status": "confirmed",
      "submitted_at": "2026-11-07T01:18:43.458Z",
      "updated_at": "2026-11-07T03:18:43.476Z",
      "bitcoin_block_height": 974874,
      "attestations": [
        {
          "type": "pending",
          "uri": "https://alice.btc.calendar.opentimestamps.org",
          "commitment": "6aee7c7407701f040c8278a55e19a5863e7a101f65d104d04f5bf7aa18869c7830fefac79267df026b47f545"
        },
        {
          "type": "bitcoin",
          "block_height": 974874,
          "merkle_root": "fa522f272a37cb03554d5be30f11a1564362627a0d248c198befb5a303c3a302"
        }
      ]
    },
    {
      "calendar": "https://b.pool.opentimestamps.org",
      "status": "confirmed",
      "submitted_at": "2026-11-07T01:18:43.458Z",
      "updated_at": "2026-11-07T03:18:43.476Z",
      "bitcoin_block_height": 974877,
      "attestations": [
        {
          "type": "pending",
          "uri": "https://bob.btc.calendar.opentimestamps.org",
          "commitment": "6aee7c7515e6b8c2c8d1ca292ff27791e6265fd1460360833e28a88a62e35196daea7c8f50bf1fc62489151a"
        },
        {
          "type": "bitcoin",
          "block_height": 974877,
          "merkle_root": "dee625f48434576e86df10e80f2912b1c31b96672232e47e103806c1faef5814"
        }
      ]
    },
    {
      "calendar": "https://finney.calendar.eternitywall.com",
      "status": "confirmed",
      "submitted_at": "2026-11-07T01:18:43.458Z",
      "updated_at": "2026-11-07T03:18:43.476Z",
      "bitcoin_block_height": 974877,
      "attestations": [
        {
          "type": "pending",
          "uri": "https://finney.calendar.eternitywall.com",
          "commitment": "6aee7c74e873a5b76cb73d3c023d0eafd5b98d6fe330cc42a96be13a7deefa4b0801376ff46489dee21cc3ea"
        },
        {
          "type": "bitcoin",
          "block_height": 974877,
          "merkle_root": "dee625f48434576e86df10e80f2912b1c31b96672232e47e103806c1faef5814"
        }
      ]
    }
  ],
  "proof_url": "https://www.a2ally.com/v1/ledger/blocks/50/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."
}