zkSync Era

Validity proofs ensure state correctness

Each update to the system state must be accompanied by a ZK Proof that ensures that the new state was derived by correctly applying a series of valid user transactions to the previous state. Once the proof is processed on the Ethereum blockchain the L2 block is instantly finalized.

1. Validity proofs - zkSync FAQ

Zero knowledge SNARK cryptography is used

Despite their production use ZK-SNARKs are still new and experimental cryptography. Cryptography has made a lot of advancements in the recent years but all cryptographic solutions rely on time to prove their security. In addition ZK-SNARKs require a trusted setup to operate.

• Funds can be stolen if the cryptography is broken or implemented incorrectly.

1. Cryptography used - zkSync FAQ

All data required for proofs is published on chain

All the data that is used to construct the system state is published on chain in the form of cheap calldata. This ensures that it will always be available when needed.

The system has a centralized operator

The operator is the only entity that can propose blocks. A live and trustworthy operator is vital to the health of the system.

• MEV can be extracted if the operator exploits their centralized position and frontruns user transactions.

Users can force any transaction via L1

If a user is censored by L2 Sequencer, they can try to force transaction via L1 queue. Right now there is no mechanism that forces L2 Sequencer to include transactions from L1 queue in an L1 block.

1. L1 - L2 interoperability - Developer's documentation'

Regular exit

The user initiates the withdrawal by submitting a transaction on L2. When the block containing that transaction is proven the funds become available for withdrawal on L1. Finally the user submits an L1 transaction to claim the funds. This transaction requires a merkle proof.

1. Withdrawing funds - zkSync documentation

Forced exit

If the user experiences censorship from the operator with regular exit they can submit their withdrawal requests directly on L1. The system is then obliged to service this request. Once the force operation is submitted if the request is serviced the operation follows the flow of a regular exit. Note that this mechanism is not implemented yet.

• Funds can be frozen if a user withdrawal request is censored (CRITICAL).

1. L1 - L2 interoperability - Developer's documentation