block header [English]

InterPARES Definition

No definition in earlier IP projects. ITrust definition not yet developed.

Other Definitions

  • Bitcoin Developer Glossary 2017 (†791 s.v. "Block Header"): An 80-byte header belonging to a single block which is hashed repeatedly to create proof of work.
  • Pfeffer [2017] (†844 s.v. "blockHeader"): Relates a Block to its Block header data. The Block header data contains 15 pieces of information: 1. the parent hash, 2. the Uncle hash, 3. a beneficiary address, 4. a state root hash, 5. a transactions root hash, 6. a receipts root hash, 7. a log bloom filter, 8. the difficulty value, 9. the Block number, 10. the gas limit of the Block, 11. the gas used by all transactions in the Block, 12. a scalar timestamp in unix time() format, 13. a byte array containing extra data, 14. a mix hash and 15. the Block nonce. The property is functional because a Block can have only exactly one Block header.


  • Bitcoin Wiki Vocabulary [2017] (†796 s.v. "Merkle root"): Every transaction has a hash associated with it. In a block, all of the transaction hashes in the block are themselves hashed (sometimes several times -- the exact process is complex), and the result is the Merkle root. In other words, the Merkle root is the hash of all the hashes of all the transactions in the block. The Merkle root is included in the block header. With this scheme, it is possible to securely verify that a transaction has been accepted by the network (and get the number of confirmations) by downloading just the tiny block headers and Merkle tree -- downloading the entire block chain is unnecessary. This feature is currently not used in Bitcoin, but it will be in the future. (†2303)
  • Buterin [2017] (†818 s.v. "Merkle Trees"): The "hash" of a block is actually only the hash of the block header, a roughly 200-byte piece of data that contains the timestamp, nonce, previous block hash and the root hash of a data structure called the Merkle tree storing all transactions in the block. (†2119)
  • Buterin [2017] (†818 s.v. "Merkle Trees): A protocol known as "simplified payment verification" (SPV) allows for another class of nodes to exist, called "light nodes", which download the block headers, verify the proof of work on the block headers, and then download only the "branches" associated with transactions that are relevant to them. (†2120)
  • Buterin [2017] (†818 s.v. "Mining Centralization"): The Bitcoin mining algorithm works by having miners compute SHA256 on slightly modified versions of the block header millions of times over and over again, until eventually one node comes up with a version whose hash is less than the target (currently around 2^192). (†2121)
  • Wood 2014 (†803 p. 12): Since a block header includes the difficulty, the header alone is enough to validate the computation done. Any block contributes toward the total computation or total difficulty of a chain. (†2047)