Most people see zero knowledge rollups as the end game for blockchain scaling because they can guarantee super-high transaction speeds. However, light speed transactions come with the dreaded risk of centralization.
The Polygon (MATIC/USD) Hermez team created Proof-of-Efficiency (PoE), an innovative consensus mechanism, Polygon wrote on their blog. It aims to offer the following key properties:
- Efficiency as key to network performance
- Permissionless access to production of transactions batches on the rollup
- Avoiding control by any single party
- Total validation effort proportional to the value in the network
- Protection from malicious attacks
Rollups remain dependent on L1 for data storage and security. Dual-layer topology is at the core of how PoE functions. The protocol for creating transaction batches is comprised of a two-step model splitting activities between two different parties:
Sequencers and aggregators
Anyone can be either party because these roles are both permissionless. Sequencers gather transactions from users. They then choose and pre-process new batches of L2 data and transmit transactions for recording to Layer 1.
Aggregators take part in the PoE consensus protocol. By being the first aggregator to create the validity proof of a new state of the L2, you earn the right to do it.
According to this theoretical setup, the system sends all transaction fees to the corresponding sequencer of each batch. Part of the fees go to the aggregator, who created the validity proof for the batch.
With this model, centralized control is avoided and many potential attacks are prevented. However, there’s still an issue. Any sequencer can propose a batch, but what if no aggregators take part?
To solve this potential problem, Polygon Hermez would use a Boot Aggregator to guarantee full operation of the network during the bootstrapping phase.
PoE is supported through the team’s experience with the existing Proof-of-Donation. In the next few months, Polygon Hermez plans to launch PoE in a testnet environment.
ZK Thesis: at the core of Polygon’s vision
ZK rollups are at the core of Polygon’s vision. Accordingly, the ecosystem has invested the sum of $1 billion in its ZK-related efforts. They were a centerpiece of Polygon’s strategic vision in the Zero Knowledge Thesis published last year.