Finality - ZKsync Docs

Finality in blockchain systems refers to the point at which a transaction is considered irreversible and permanently part of the blockchain. This concept is crucial for ensuring transaction security and reliability.

Finality on Ethereum

On Ethereum, finality is typically achieved after 2 epochs, which translates to approximately 13 minutes under normal network conditions. This duration allows for sufficient block confirmations to prevent reversals and ensure that transactions are settled securely.

Finality on ZKsync Era

ZKsync Era, as a Layer 2 (L2) rollup, ties its finality and security mechanisms to those of the underlying Layer 1 (L1) Ethereum chain. The steps involved in reaching finality in ZKsync Era include:

Batch Formation: Transactions are collected and grouped into a batch. This step generally takes a few minutes.
Batch Commitment: The complete batch is committed to the Ethereum blockchain.
Proof Generation: A cryptographic proof that validates the entire batch is generated. This process typically takes about an hour.
Proof Submission: The generated proof is submitted to an Ethereum smart contract for verification.
Batch Finalization: The batch undergoes a final verification and is settled on Ethereum. This step includes a delay of approximately 21 hours as a security measure during the alpha phase of ZKsync Era.

Overall, the complete finality time for a transaction on ZKsync Era is around 24 hours, aligning with the finality of the corresponding Ethereum block.

Advancements in validity proof research are continuously being made, promising potential reductions in proof generation times and, consequently, faster finality periods in the future.

Instant confirmations

While the full finality process on ZKsync Era can take up to 24 hours, transactions are treated with instant confirmation for user convenience:

Immediate Transaction Display: Once submitted, transactions are quickly shown in the user interface and API as unconfirmed.
Immediate Asset Usability: Users can immediately utilize the transferred assets for further transactions, which may even be included in the same ZKsync Era batch.

This feature enables a seamless user experience, although more cautious users may opt to wait for the transaction to reach full finality or pass any intermediate steps before fully trusting the transaction's completion.

ZKsync fee structure

Understanding the structure of fees in ZKsync.

Data availability

An in-depth look at how ZKsync ensures data availability through state diffs and compresses data to optimize L1 submissions, plus tools for reconstructing L2 state from L1 public data.