What is Slashing mechanism in POS?
By Inkarias - 2019-12-07
Slashing mechanismHowever, in POS-type consensus system where main actors are delegators/bakers, it is also essential to establish a control system to prevent and punish behaviours that could be detrimental to the system and investors as a whole and ensure a complete balance in the system. Slashing has therefore been put in place to solve this major problem in order to provide a durable solution while guaranteeing the integrity and durability of the system. In short, Slashing is the fact that the chosen validator or baker is punished for a fault he has committed and is a protection mechanism by which the network disrupts abnormal or fraudulent behaviour to ensure its complete integrity. This mechanism isn’t implemented in all POS systems and only concerns the LPOS/BPOS/DPOS types.In short, a slashing is an event where the validator gives up a defined proportion of staked tokens, which are then burned or redistributed to other stakeholders proportionally.
When can that system be used?Slashing is implemented in few currencies we have been introducing earlier such as Cosmos, Algorand, IrisNet and more and is used for several possible cases:
- A liveness fault where the validator node does not participate in the network consensus for a long time and misses several blocks. We can quote IrisNet and Cosmos as examples for this case. We can quote a downtime as example: if the node is not signing transactions for a certain amount of time (native blockchain parameters are defined by the respective team at launch and depends on the setup), it will be considered inactive and may start losing out on block rewards. After a certain threshold is crossed, it might also be slashed, resulting in a permanent loss of stake and the potential suspension from the validator set. This can happen when a node’s cloud infrastructure goes down, or if the software becomes out of sync, for example.
- A security fault which disturbs the network consensus by validating/verifying twice or more the same blocks. This case is also called double-baking or double-endorsing in the case of Tezos, or double-signing in the case of Cosmos & IRISnet. This is mainly the source of problems for a majority of currencies. Double signing or the action of signing two blocks at the same block height, is more severely punished by the different protocol parameters. This can either happen when an opposite validator is trying to attack the network or because of an unstable and not reliable infrastructure, leading to one key signing the same block twice.
- A governance fault where the validator voted multiple times on the same consensus process, and these votes contradict each other, or he did not vote at all. Cosmos and IrisNet can also be quoted as examples. This is the same principle as double-signing, the validator will lose a part of its stakes or the entirety depending on the case.