Disputes Slashing/Hardening

[eskimor]

The Vision

Polkadot is a sharded blockchain. Some validators check some of the parachain blocks. When there's a disagreement about validity of parachain block, a dispute process starts. The checks will escalate to every validator. Once the dispute is resolved, we need to slash and disable validators accordingly to their misbehavior.

Board here.

Disputes

General goal of disputes improvements is to make them more spam resilient.

Slashing

Overall Strategy

Designing slashing systems is a very complex topic and pretty much impossible to get 100% right, especially if you consider real world issues, like machines not being equal, bugs, load variance, hardware faults, ... Therefore we need to be able to rely on governance for fixing any faulty slashes. By being able to rely on governance in extreme edge cases we can err on making the system more secure.

For this we need to ensure/overall strategy:

• Unjustified slashes won't have a significant impact on validators, if reverted by governance. In particular validators should not lose their nominators.
• Disabling of honest validators (due to unjustified slashes), will never be threatening the system's security. (Security over liveness.)
• Make handling of time more deterministic/robust (outside of scope for this ticket, will be a separate project: time disputes)
• Add all of this to the guide (describe the overall strategy for handling slashing)

Plan Details

• Current-session disputes slashing runtime/disputes: slashing polkadot#5535.
• Test the limits of the slashing logic in substrate [don't merge] zombienet slashing test polkadot#5978 (no longer necessary now that chilling has been removed)
• Ensure there are no disputes due to bugs on Kusama Make Kusama dispute free #783
• Enable slashing on Kusama kusama: enable dispute slashes polkadot#5974
• Enable slashing on Polkadot runtime/polkadot: enable disputes rewards and slashing polkadot#6960
• Past-session disputes slashing disputes: implement past session slashing polkadot#5947
• Validator disabling disputes: implement validator disabling #784
• Escalate punishment on repeated disputes disputes: punishment on repeated dispute initiations (stale) #785
• Enable past-session slashing and disabling on Kusama
• Enable past-session slashing and disabling on Polkadot