IIP-51: Switch Consensus Voting From Delegate Count To Voting Power

iip-51.md

@@ -0,0 +1,51 @@
+```
+IIP: 51
+Title: Switch Consensus Voting from Delegate Count to Voting Power
+Author: Seedlet <zhi@iotex.io>
+Discussions-to: TBD
+Status: Draft
+Type: Core
+Category: Core
+Created: 2025-07-24
+```
+
+## Simple Summary
+This proposal changes IoTeX's consensus logic from a simple majority of delegates to a majority based on total voting power". This shift ensures that governance outcomes reflect actual stake-weighted consensus and improves the representiveness and security of IoTeX.
+
+## Abstract
+Currently, consensus on the IoTeX blockchain is determined by the NUMBER of supporting delegates, regardless of their individual voting powers. This can allow low-stake delegate to control consensus and underrepreseting high-voting-power delegates. It leads to governance decisions that do not reflect the true economic stake of the community. This proposal replaces the delegate-count-based majority with a stake-weighted rule: consensus will require support from delegates representing more than two-thirds of the total voting power. This change enhances fairness, improves security, and incentivizes greater voter engagement.
+
+## Specification
+In each epoch, N delegates are randomly selected from the top T candidates by voting power. Under the current consensus algorithm, more than 2/3 * N delegates must sign off to finalize a block. In the current protocol, T is set to 36, and N is set to 24.
+
+With this proposal, consensus will instead require that the sum of voting power from the supporting delegates exceeds 2/3 of the total voting power of the selected N delegates. Block rewards and epoch rewards will remain unchanged.
+
+## Rationale
+The current delegate-count rule enables adversarial behavior such as bribing many low-power delegates to approve a block which potentially leads to attacks.
+
+By switching to stake-weighted consensus, the system better aligns incentives, improves resistance to collusion, and reflects the true will of voters.
+
+## Backwards Compatibility
+This is a consensus-level change. It is not backwards compatible and will require a hardfork upgrade.
+
+## Test Cases
+| Voting Power       | Delegate Count        | Consensus Reached |
+|--------------------|-----------------------|-------------------|
+| Sufficient (> 2/3) | Sufficient (> 2/3 N)   | ✅ Yes             |
+| Sufficient         | Insufficient          | ✅ Yes             |
+| Insufficient       | Sufficient            | ❌ No              |
+| Insufficient       | Insufficient          | ❌ No              |
+
+Simulation tests on testnet will cover cases with various voting power and delegate participation combinations.
+
+Only cases where the voting power exceeds two thirds of the total voting power among N selected delegates will result in successful consensus.
+
+Additionally, performance tests will be conducted to ensure that replacing delegate-count-based consensus with voting-power-weighted consensus does not degrade:
+- block finality time
+- overall consensus responsiveness
+
+## Implementation
+This change will require modifications to the consensus module and validator vote-counting logic. We also recommend updating frontend and explorer interfaces to display voting power per block, enabling more transparent validation of consensus decisions.
+
+## Copyright
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).