AltLayer MACH

AltLayer's MACH is a fast finality layer designed to enhance Ethereum rollups by providing quicker transaction confirmations and ensuring the integrity of rollup state transitions. It is built to handle both Zero-Knowledge (ZK) and Optimistic rollups, supporting various proof systems and runtimes. MACH aims to ensure crypto-economic security and optimize performance across rollup systems.

MACH operates with three state validity modes:

Pessimistic Mode: In this mode, every transaction is considered invalid by default and must be re-executed by the MACH network to confirm its validity. Although secure, this mode is inefficient as it essentially requires the MACH network to function as full nodes for the rollup, which demands significant computational resources.

Optimistic Mode: Here, the rollup operator asserts the validity of a state commitment. Challenges can be raised by any node in the MACH network, which then triggers a bisection protocol to resolve disputes. This approach allows the network to operate in a more resource-efficient manner, only intervening when disputes arise. Alternatively, ZK proofs can be generated on-demand during challenges for even stronger security.

Validity Proof Mode: MACH acts as a decentralized verifier for validity proofs. Rollup operators commit transactions and state updates alongside a validity proof, which the MACH network verifies. This mode also accommodates optimistic rollups by allowing external provers to generate validity proofs, which MACH can then verify. For ZK rollups, MACH enables fast finality by verifying proofs in real-time, allowing operators to aggregate them later for submission to Ethereum. This approach ensures that transactions are finalized faster without increasing the overall proving workload.

MACH is thus designed to provide flexible, efficient, and secure finality for rollups, with the ability to verify proofs more frequently and ensure quicker consensus, all while maintaining the integrity and security of the rollup process.