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Blockchain Attestation and Ethereum Attestation Service, Explained

December 20, 2023 - 6 min read

Blockchain Attestation Services, Like Ethereum Attestation Service, Can Help Cryptographically Verify On-Chain And Off-Chain Transactions

For a blockchain to reach a consensus on a transaction, validators must attest that the chain’s recent and upcoming blocks are accurate. Therefore, blockchain attestation refers to a vote made by each validator to reach a consensus on whether to approve a transaction. While blockchain attestations were initially limited to on-chain transactions, new attestation services, like Ethereum Attestation Service, can help cryptographically verify both on-chain and off-chain transactions. 

The Benefits And Use Cases Of Blockchain Attestation 

In addition to helping blockchains reach consensus, blockchain attestation has several other significant benefits and essential use cases, including: 

Facilitating Efficient Network Communication: Instead of being transmitted by each validator, attestations are aggregated within subnets before being broadcast to the entire chain. This reduces a blockchain’s computational and bandwidth overhead, increasing transaction speed and reducing gas fees. 

Improving Data Integrity: Blockchain validator data attestations don’t just include a simple “yes or no” vote; they also include other important data necessary to verify a transaction cryptographically. This includes the block root, source, slot number, validator index, and target checkpoints. The more validators attest to a transaction, the more likely the data is accurate. In addition, a relatively high number of validator attestations helps to prevent data tampering and other malicious behavior. 

Encouraging Network Participation: Instead of passively approving transactions, the attestation process can provide validators additional rewards linked to their staked balances (for PoS networks). The more validators actively create, sign, and broadcast attestations, the greater the level of accuracy the data will likely have. In addition, highly active validators significantly increase blockchain reliability and security, as active validators are far more likely to discover and report potential network security issues. 

Ethereum Blockchain Attestations: How Do They Work? 

On Ethereum, each epoch lasts around 6.4 minutes, during which validators can attest to the accuracy of the data involved in individual transactions. Specifically, validators propose network attestations for specific slots within the epoch, focusing on the first block in the current epoch and the most recent justified block, which covers both the source and target checkpoints. 

Ethereum attestations combine several components, including: 

  • Aggregation_bits: These are bitlists of validators with attestation data, including committee number, slot number, beacon block source, root, and target. The position of the bitlist is linked (mapped to) the committee validator index in the validator-specific commit. The response value, denominated in zero or one, shows whether the validators signed the data.  
  • Data: Attestations from individual validators are aggregated via subnets before being broadcast more widely to the network. The aggregator is tasked with collecting attestations over the “gossip network.” This significantly reduces network overhead. 
  • Signatures: Blockchain attestation signatures are BLS signatures. These BLS signatures aggregate the signatures of multiple individual validators to reach a consensus. After aggregating the data, the validator changes the bit corresponding to their validator index from zero to one to indicate participation. The validator signs the attestation. After signing, the signature is broadcast to the broader network. 

How Validators Are Rewarded For Attestations 

Like mining blockchains on a proof-of-work blockchain or validating transactions on a proof-of-stake chain, individual validators are rewarded for attestation submissions. These rewards include base rewards and inclusion delays. 

Validator base rewards are determined by the number of validators attesting to a piece of data and their effective staked balances (denominated in ETH for the Ethereum Attestation Service, currently the most popular attestation service in the industry). 

However, there are certain time limits in regard to validator attestation. However, these limits are somewhat flexible. Specifically, validators must submit their attestation in one epoch. However, if the validator misses the attestation in a single epoch, they can submit it with an inclusion delay int the next. 

Sometimes, attestations will not be included in a block if the block prosper has gone missing. In these scenarios, the next block proposer picks up the aggregated attestation. Then, it includes it in the upcoming block. However, in this situation, the validator’s inclusion delay does increase by one. 

Ethereum Attestation Service, Explained 

According to the Ethereum Attestation Service website: “Ethereum Attestation Service (EAS) is a public good for creating, verifying, and revoking on/off-chain attestations.” EAS allows anyone to make on-chain and off-chain attestations via registered schemas, with EAS serving as a “global base layer for trust.” 

In addition, EAS transactions are secured and settled on the Ethereum mainnet, meaning that, to an extent, they inherit a fair amount of Ethereum’s core safety and security guarantees. 

Here are a few of the types of attestations that the Ethereum Attestation service currently specializes in: 

On-Chain Attestations: 

  • Verifiable blockchain credentials
  • Claims & Web3 badges (similar to POAPs) 
  • Cryptographic proofs 
  • Decentralized identifiers

Off-Chain Attestations: 

  • Specific public statements
  • Social accounts 
  • Passports and government IDs
  • Private and corporate IDs 

Additional potential schemas and attestation applications include: 

  • Skill verification and credential badges
  • Ownership of physical objects, like homes and cars
  • Online statements, articles, books, and other online publishing 
  • Ownership of investment assets, both on-chain and off-chain
  • Digital signatures for contracts and other legal documents 
  • Votes (including government voting, corporate voting, and DAO voting)
  • Digital and physical identities (which can be used for private KYC situations) 
  • Financial status and credit score (often utilized for loan applications) 

How Ethereum Attestation Service Functions 

Technically, Ethereum Attestation Service is extremely simple and currently consists of two smart contracts that can be used for almost all attestation use cases. The first smart contract registers an attestation schema, while the other makes attestations on specific schemas. 

Additionally, EAS Scan, which is essentially a blockchain scanner for Ethereum Attestation service (much like Etherscan), can be used to create and publicly view schemas and attestations made via EAS. 

The Potential Impact and Additional Uses of Ethereum Attestation Service

According to the EAS site, Ethereum Attestation Service has ambitious goals to improve global consumer safety and create “trustless economies,” making both existing and new applications composable and trustless. 

Potential applications include: 

  • Blockchain voting  
  • NFT ticketing 
  • On-chain loans and lending protocols 
  • Land registries, deeds, and titles 
  • Social networks (centralized and decentralized) 
  • Digital signing and notary services
  • Attestations for real-world outcomes (can be used for prediction markets)
  • Proof of providence for supply chain and product origin verification applications 

In Conclusion: Blockchain Attestation Services Will Likely Increase In Popularity and Add Cross-Chain Interoperability

As we’ve discussed in this article, Blockchain attestation is an incredibly useful function for blockchain technology, as it can be used to verify everything from government voting and blockchain IDs to land ownership, social networks, and even GameFi applications. 

Despite the increasing popularity of Ethereum Attestation Service, blockchain attestation services are quite new, meaning that they haven’t quite fully caught on and are not yet widely used by the broader crypto and blockchain community. In addition, they are not yet well-known by traditional Web2 companies looking for a way to securely verify data, though this use case could also become quite popular in the near future. 

Ethereum Attestation Service is the only popular blockchain attestation service on the market today. However, with its increasing popularity, we can expect more chains to begin using attestation services in the near future. For example, the popular Ethereum Layer-2 Optimism announced in May 2023 that it would use EAS to promote additional user trust. 

In the coming months and years, we expect more Layer-1 and Layer-2 attestation services to come to market. In addition, services like Ethereum Attestation Service could become interoperable cross-chain protocols, allowing users to attest to and verify data on a wide array of chains. 

References: 

  1. Wilke, A. (Jun. 2023) Understanding Attestations: Building Consensus in Blockchain Networks. t3rn. 
  2. Ethereum Attestation Service: Attest to anything and everything. Ethereum Attestation Service
  3. Hardjono, T., Smith, N. (Mar. 2021) Towards an attestation architecture for blockchain networks. Springer Link (initially published in World Wide Web). 

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