Verifiers, also known as nodes in a blockchain network, check the validity of a block through a series of rigorous checks and processes. Here’s a detailed explanation of how this verification process typically works:
Transaction Validity: Each transaction within the block must be individually valid. This involves verifying that all transactions are correctly signed, that the inputs to each transaction are unspent, and that the transactions adhere to the network's rules[18].
Proof of Work (PoW) Verification: For blockchains that use PoW, verifiers check whether the block header’s hash meets the network-determined difficulty target. This means the block’s hash must be below a certain value, which proves that a significant amount of computational work has been done[4][15]. The hash is calculated using the block’s header information, which includes a reference to the hash of the previous block, thus linking the blocks securely.
Block Header Integrity: The block header contains several pieces of critical data that verifiers check:
The hash of the previous block to ensure continuity of the blockchain.
The timestamp to confirm that the block was created within the allowed time frame.
The nonce value that was used to achieve the successful hash under the PoW protocol[13].
Block Size and Structure: Verifiers check that the block size is within the limits set by the blockchain protocol and that the structure of the block adheres to the required format, including the correct ordering of transactions and the presence of a valid Merkle root[13].
Consensus Rules: Depending on the specific blockchain, there may be additional consensus rules that need to be checked. These can include rules related to the blockchain’s specific features, such as smart contracts, or rules about the creation of new tokens within the block[18].
Link to the Blockchain: Finally, the block must correctly...
