Ethereum is taking a significant leap toward enhancing transaction speeds with the introduction of "millisecond" preconfirmations via a new Remote Procedure Call (RPC). This development promises to drastically reduce confirmation times, offering users a near-instant feedback mechanism for their transactions.

What are Preconfirmations?

Preconfirmations (preconfs) represent a major step forward, allowing a commitment to include a transaction in a block even before the block is fully formed. In essence, a preconfirmation is a signed guarantee from a block proposer that a specific transaction will be included at a predetermined time. Users pay a tip to these preconfers for the service. By acquiring preconf promises from upcoming block proposers, users can gain assurance of speedy execution, potentially achieving latencies as low as 100ms.

How it Works

The preconfirmation process involves several key players in the Ethereum ecosystem:

• Builders: Prepare blocks with the most profitable transactions.
• Proposers: Validators who decide which block gets published. These "preconfers" issue signed promises guaranteeing transaction inclusion and are compensated with tips.
• Relays: Connect builders and proposers.

To secure a preconfirmation, users will need to send a request to a preconfer. The "preconf-share" middleware acts as a matchmaker, connecting user requests with block proposers. Operators, running AVS software on top of EigenLayer, can then decide whether to promise a preconfirmation based on hints and tips provided. These promises are ranked by preconf-share according to user preferences.

This process is facilitated through RPC endpoints, which streamline the interaction for users by simplifying the passing of arguments and extra parameters. The new RPC acts as a JSON-RPC wrapper on top of Preconf-Share, making it easier for wallets like Metamask to integrate with the preconfirmation system.

Benefits of Millisecond Preconfirmations

The implementation of millisecond preconfirmations offers numerous advantages:

• Faster Confirmations: Reduces confirmation times from seconds to milliseconds, providing near-instant feedback.
• Reduced Failed Transactions: Especially beneficial in fast-moving markets where state changes rapidly.
• Greater Censorship Resistance: Ensures transaction inclusion even if some builders reject it.
• Cost Predictability: Allows users to anticipate gas costs and avoid surprises during network congestion.

Technical Details and Implementation

The introduction of preconfirmations leverages EigenLayer as a crucial infrastructure component, securing preconfer guarantees through a slashing mechanism. Operators running the AVS software must be block proposers capable of including preconfirmation transactions. Failure to fulfill preconfirmation promises results in on-chain slashing, verified using Relic Protocol.

To mitigate potential drawbacks and maintain systemic integrity, the Multi-Round MEV-Boost (MR-MEV-Boost) mechanism is introduced. This mechanism divides each block slot into smaller intervals, enabling partial blocks to be pre-confirmed in rounds, reducing latency while preserving composability across Layer 1 (L1) and Layer 2 (L2) transactions.

Challenges and Considerations

While preconfirmations offer substantial improvements, there are challenges to consider:

• Preconfirmation Tip Estimation: Estimating fair tips is complex, depending on the preconfer's current state and requiring complex modifications to wallets.
• Liveness Fallback: Users may need to acquire promises from multiple preconfers to ensure resilience against promise liveness faults.
• Replay Protection: To prevent replay attacks, transaction validity should be tied to the preconf condition, potentially requiring a new L2 transaction type.

Looking Ahead

The introduction of millisecond preconfirmations marks a significant advancement in Ethereum's ongoing evolution. By addressing latency and composability challenges, preconfirmations pave the way for a more efficient, user-friendly, and robust blockchain ecosystem. As the technology matures, further research and development will focus on optimizing slashing conditions, enhancing L1-L2 transaction pipelines, and potentially enshrining preconfirmation protocols into the Ethereum consensus layer.