curl --request GET \
  --url https://tonapi.io/v2/liteserver/get_shard_block_proof/{block_id}

{
  "masterchain_id": {
    "workchain": 4294967295,
    "shard": "800000000000000",
    "seqno": 30699640,
    "root_hash": "131D0C65055F04E9C19D687B51BC70F952FD9CA6F02C2801D3B89964A779DF85",
    "file_hash": "A6A0BD6608672B11B79538A50B2204E748305C12AA0DED9C16CF0006CE3AF8DB"
  },
  "links": [
    {
      "id": {
        "workchain": 4294967295,
        "shard": "800000000000000",
        "seqno": 30699640,
        "root_hash": "131D0C65055F04E9C19D687B51BC70F952FD9CA6F02C2801D3B89964A779DF85",
        "file_hash": "A6A0BD6608672B11B79538A50B2204E748305C12AA0DED9C16CF0006CE3AF8DB"
      },
      "proof": "131D0C65055F04E9C19D687B51BC70F952FD9CA6F02C2801D3B89964A779DF85"
    }
  ]
}