1.Description

BEP-126: Introduce Fast Finality Mechanism was included in the Luban hard fork, which was activated on April 27, 2023, on the BSC mainnet.

Fast Finality relies heavily on the voting behavior of validators, which is governed by three key rules:

1. A validator must not publish two distinct votes for the same height. (Rule 1)
2. A validator must not vote within the span of its other votes . (Rule 2)
3. Validators always vote for their canonical chain’s latest block. (Rule 3)

To enforce these rules, Fast Finality includes a slashing mechanism designed to prevent validators from submitting votes that violate these voting rules. Initially, the slashing mechanism was disabled by default to allow for further verification of Fast Finality's reliability. However, it is now advisable to enable it because:

1. Reliability: Fast Finality has demonstrated strong performance over the past two years, even under high traffic volumes and shorter block intervals.
2. Widespread Adoption: An increasing number of ecosystem projects have integrated the Fast Finality feature, making its reliability crucial for the BSC ecosystem.

Meanwhile, this proposal will update 2 parameters for current slash and reward amounts:

• felonySlashAmount: We will reduce the penalty from 200 BNB to 100 BNB. The previous amount represents a significant loss, which could sometimes result from maintenance errors rather than actual harm to the network. This parameter is also used for double sign slash, so the double sign slash amount will also be lowered to 100 BNB.
• felonySlashRewardRatio: We will also lower the reward for submitters from approximately 20 BNB to approximately 10 BNB. With the reduced slash amount, it is appropriate to adjust the reward accordingly. A reward of around 10 BNB remains quite attractive. This parameter is also used for double sign submitter reward, so the double sign submitter reward will also be lowered to approximately 10 BNB.

2.About FastFinality Malicious Vote Slash

2.1.Slash Rule

• The validator who violates the first two vote rules will be slashed
• The evidence can be submitted by anyone, whenever someone sees the malicious behavior, he can submit the evidence to a designed system contract
• Once the evidence has been proved valid, the malicious validator will be put into jail and punished with a huge fine, like 200 BNBs. The submitter can get part of the rewards from our system reward contract.
• The malicious validator will only be punished once. Once the malicious validator has been put into jail, the later submitters that submit malicious evidence of the validators won’t get any reward.

2.2.Details About Slash & Reward

• Evidence Scope: Evidence will expire after a certain period, governed by the parameter felonySlashScope, which is currently set to 1 day.
• Slash Amount: The penalty amount is governed by the parameter felonySlashAmount, currently set at 200 BNB, will be updated to 100 BNB after this proposal. The slashed BNB will be transferred to SystemReward contract.
• Jail Duration: The malicious validator will be removed from the active validator set immediately and imprisoned, with a jail duration governed by the parameter felonyJailTime, currently set to 5 days on testnet and 30 days on mainnet.
• Submitter Reward: The submitter of the evidence will be rewarded by the SystemReward contract, with the reward ratio governed by the parameter felonySlashRewardRatio, currently set at 20%, will be updated to 10% after this proposal. This means the reward will be approximately 10 BNB after this proposal.

3.Parameter To Be Updated

There is only 3 parameters to be updated:

SlashContract: 0x0000000000000000000000000000000000001001

• enableMaliciousVoteSlash: from false to true
• felonySlashRewardRatio: from 0x0000000000000000000000000000000000000000000000000000000000000014(20) to 0x000000000000000000000000000000000000000000000000000000000000000a(10)

StakeHubContract: 0x0000000000000000000000000000000000002002

• felonySlashAmount: from 0x00000000000000000000000000000000000000000000000AD78EBC5AC6200000(200BNB) to 0x0000000000000000000000000000000000000000000000056BC75E2D63100000(100BNB)