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Block Header#

The block header in Ergo serves as a concise summary of a block's critical information. It plays a vital role in maintaining the integrity and security of the blockchain.

Functions#

  • Chain Synchronization: Headers enable efficient synchronization between nodes on the network. By exchanging and validating headers, nodes can quickly agree on the current state of the blockchain without downloading every full block.
  • Proof-of-Work Validation: The header contains information necessary to verify the miner's Proof-of-Work (PoW) solution, ensuring that the block meets the network's difficulty requirements.
  • Block Integrity: Headers include hashes that link to other sections of the block (transactions, proofs, extension), guaranteeing the integrity of the entire block. Any tampering with the block's content would result in a mismatch of these hashes.

Components#

The Header class in Header.scala defines the structure of the block header. Here's an overview of the key fields:

  • version: Indicates the protocol version used to create the block. This allows for future upgrades and changes to the blockchain while maintaining backward compatibility.
  • parentId: The ID of the previous block in the blockchain. This links blocks together, forming a chain.
  • ADProofsRoot: A cryptographic digest of the proofs that validate changes to the UTXO set (the record of unspent transaction outputs).
  • stateRoot: A digest representing the root of the Merkle tree that captures the state of the UTXO set after this block is applied.
  • transactionsRoot: A digest of the Merkle root of all transactions included in the block.
  • timestamp: The time when the block was created, as reported by the miner.
  • nBits: Represents the difficulty target for the block, determining how hard it was to mine.
  • height: The block's height in the blockchain (genesis block has height 1).
  • extensionRoot: A digest of the Merkle root of the extension section, which can contain arbitrary data.
  • powSolution: The solution to the Proof-of-Work puzzle, demonstrating that the miner expended the necessary computational effort.
  • votes: Votes cast by miners to signal preferences for changes to consensus parameters.
  • unparsedBytes: A field to accommodate future protocol upgrades, allowing for the inclusion of data not yet parsed by current versions.
  • sizeOpt: An optional field storing the size of the header to optimize performance.

Key Concepts#

  • Merkle Tree: A data structure used extensively in blockchains to efficiently verify data integrity. It allows for quick verification that a particular piece of data is included in a larger set.
  • UTXO (Unspent Transaction Output) Set: The record of all unspent transaction outputs on the blockchain, representing the current distribution of the cryptocurrency.
  • Proof-of-Work (PoW): A consensus mechanism that requires miners to solve a computationally intensive puzzle to add blocks to the blockchain. This ensures the security and immutability of the chain.