The Block Model¶

A block has the following structure:

{
  "id": "<hash of block>",
  "block": {
    "timestamp": "<block-creation timestamp>",
    "transactions": ["<list of transactions>"],
    "node_pubkey": "<public key of the node creating the block>",
    "voters": ["<list of public keys of all nodes in the cluster>"]
  },
  "signature": "<signature of block>"
}

id: The hash of the serialized inner block (i.e. the timestamp, transactions, node_pubkey, and voters). It’s used as a unique index in the database backend (e.g. RethinkDB or MongoDB).
block:
- timestamp: The Unix time when the block was created. It’s provided by the node that created the block.
- transactions: A list of the transactions included in the block.
- node_pubkey: The public key of the node that created the block.
- voters: A list of the public keys of all cluster nodes at the time the block was created. It’s the list of nodes which can cast a vote on this block. This list can change from block to block, as nodes join and leave the cluster.
signature: Cryptographic signature of the block by the node that created the block (i.e. the node with public key node_pubkey). To generate the signature, the node signs the serialized inner block (the same thing that was hashed to determine the id) using the private key corresponding to node_pubkey.

Working with Blocks¶

There’s a Block class for creating and working with Block objects; look in /bigchaindb/models.py. (The link is to the latest version on the master branch on GitHub.)