In the world of blockchain and decentralized networks, validator attestations and voting protocols play a critical role in ensuring the integrity and security of these systems. These mechanisms allow for the verification of transactions, reaching a consensus on the state of the network, and making crucial decisions that impact the future of the network.
A validator is a node in a blockchain network that is responsible for verifying transactions and adding them to the blockchain. These nodes play a crucial role in maintaining the security and reliability of the network by verifying the validity of transactions and ensuring that they conform to the network's consensus rules.Â
For example, validators in Ethereum’s proof of stake protocol, vote for a blockchain fork based on the total accumulated staked ETH that has voted for it. A blockchain fork involves a parent and a set of child blocks, with only one child block eventually being considered part of the canonical chain. Blockchain forks are common and occur when a synchrony assumption is violated.Â
A vote, or an attestation, cast by a Validator consists of the newly proposed beacon block, the source block, and the target block. The attestation is counted in two voting protocols:Â
Fork-choice, which determines the new tip of the canonical chain based on the heaviest chain rule (LMD GHOST), andÂ
Checkpoint candidate, which verifies if a block will become the next candidate for finalization.Â
Validator attestations refer to the process by which validators cast their votes on a particular block of transactions. This vote is known as an "attestation" and is used to determine the validity of the block and to reach a consensus on the state of the network. For example, in a PoS network, once a block of transactions is proposed, validators will cast their votes on the block based on their evaluation of the transactions in the block. If a sufficient number of validators agree that the transactions in the block are valid, the block will be considered to be "finalized" and added to the blockchain.Â
We also have two types of finality. We have the:
Weight-based finality andÂ
Absolute finality
These are two-tier systems for determining whether a block is final and irreversible.
This process is one of the most important aspects of validator attestations is that they are used to establish the order of transactions and prevent double-spending. When a validator attests to a block of transactions, it is effectively saying that it believes that these transactions are valid and that they should be included in the blockchain. This process of finalizing blocks is crucial to the security and reliability of the network, as it ensures that all transactions are properly recorded and that the state of the network is updated accurately.
Validator attestations are also used to reach consensus on the state of the network. When a large number of validators attest to the same block, it is taken as evidence that the network has reached consensus on the state of the network and that the block is considered to be the most up-to-date and accurate representation of the network's state.
In addition to validator attestations, voting protocols are another important aspect of blockchain and decentralized networks. Voting protocols are used to make important decisions about the future direction of the network and to implement changes to the network's consensus rules.Â
These protocols allow for decision-making in a decentralized and democratic manner, with each validator having an equal say in the outcome of the vote. For example, in a PoS network, a voting protocol might be used to decide whether or not to implement a hard fork, which is a major change to the network's consensus rules that can result in the creation of a new blockchain.Â
Now, assuming a Validator is online and actively participating in the Ethereum proof-of-stake protocol, they will consider the blockchain fork with the most accumulated staked ETH that has voted for it as the "canonical chain" or the true blockchain. The voting weight of a Validator is determined by their effective balance at the time of voting, including their initial deposit of 32 ETH, rewards earned over time, and penalties suffered.
Validators cast their votes using the fork-choice rule, which is used to resolve blockchain forks and follows the heaviest-chain rule, and the checkpoint candidate, which is used to verify if a supermajority of Validators agree on the same view of the canonical chain's tip.Â
The combination of these two voting protocols provides evidence that a supermajority of Validators are in agreement, both in the short-term and long-term view of the blockchain, and helps ensure that all blocks and attestations are widely propagated in a timely manner.Â
Validators are constrained to cast only one vote in an epoch and breaking this rule can result in a slashing event. This will eject the Validator from the protocol and result in a forfeiture of a portion of their staked ETH.
Hence, the fork-choice protocol helps resolve blockchain forks and converge on a single blockchain fork while the checkpoint candidate protocol verifies if a supermajority of Validators agrees on the same view of the canonical chain's tip.
Conclusion:
Validator attestations and voting protocols play a crucial role in the security and reliability of blockchain and decentralized networks. They ensure that transactions are properly validated, that the state of the network is accurately recorded, and that important decisions about the future direction of the network are made in a decentralized and democratic manner. These mechanisms are essential for maintaining the trust and stability of decentralized networks, and their continued development and improvement will be crucial for the growth and success of the blockchain industry.