mirror of https://github.com/serai-dex/serai.git synced 2024-11-17 09:27:36 +00:00

* Initial work on a Validator Sets pallet

* Update Validator Set docs per current discussions

* Update validator-sets primitives and storage handling

* Add validator set pallets to deny.toml

* Remove Curve from primitives

Since we aren't reusing keys across coins, there's no reason for it to be
on-chain (as previously planned).

* Update documentation on Validator Sets

* Use Twox64Concat instead of Identity

Ensures an even distribution of keys. While xxhash is breakable, these keys
aren't manipulatable by users.

* Add math ops on Amount and define a coin as 1e8

* Add validator-sets to the runtime and remove contracts

Also removes the randomness pallet which was only required by the contracts
runtime.

Does not remove the contracts folder yet so they can still be referred to while
validator-sets is under development. Does remove them from Cargo.toml.

* Add vote function to validator-sets

* Remove contracts folder

* Create an event for the Validator Sets pallet

* Remove old contracts crates from deny.toml

* Remove line from staking branch

* Remove staking from runtime

* Correct VS Config in runtime

* cargo update

* Resolve a few PR comments on terminology

* Create a serai-primitives crate

Move types such as Amount/Coin out of validator-sets. Will be expanded in the
future.

* Fixes for last commit

* Don't reserve set 0

* Further fixes

* Add files meant for last commit

* Remove Staking transfer

2023-01-04 22:52:41 -05:00

3.7 KiB

Raw Blame History

Validator Sets

Validator Sets are defined at the protocol level, with the following parameters:

bond (Amount): Amount of bond per key-share.
coins (Vec<Coin>): List of coins within this set.
participants (Vec<Coin>): List of participants within this set.

Validator Sets are referred to by ValidatorSetIndex yet have their data accessible via ValidatorSetInstance.

At launch, there will solely be Validator Set 0, managing Bitcoin, Ether, DAI, and Monero.

Participation in the BFT process

All Validator Sets participate in the BFT process described under Consensus. Specifically, a block containing In Instructions for a coin must be approved by the BFT majority of the Validator Set responsible for it, along with the BFT majority of the network by bond.

At this time, In Instructions for a coin are only expected to be included when a validator from the Validator Set managing the coin is the producer of the block in question.

Since there is currently only one Validator Set, the aforementioned BFT conditions collapse to simply the BFT majority by bond. Ensuring BFT majority per responsible Validator Set is accordingly unimplemented for now.

Multisig

Every Validator Set is expected to form a t-of-n multisig, where n is the amount of key shares in the Validator Set and t is n * 2 / 3 + 1, for each of its networks. This multisig is secure to hold coins up to 67% of the Validator Set's bonded value. If the coins exceed that threshold, there's more value in the multisig than in the supermajority of bond that must be put forth to control it. Accordingly, it'd be no longer financially secure, and it MUST reject newly added coins which would cross that threshold.

Multisig Creation

Multisigs are created by processors, communicating via their Coordinators. They're then confirmed on chain via the validator-sets pallet. This is done by having 100% of participants agree on the resulting group key. While this isn't fault tolerant, a malicious actor who forces a t-of-n multisig to be t-of-n-1 reduces the fault tolerance of the multisig which is a greater issue. If a node does prevent multisig creation, other validators should issue slashes for it/remove it from the Validator Set entirely.

Due to the fact multiple key generations may occur to account for faulty/malicious nodes, voting on multiple keys for a single coin is allowed, with the first key to be confirmed becoming the key for that coin.

Placing it on chain also solves the question of if the multisig was successfully created or not. Processors cannot simply ask each other if they succeeded without creating an instance of the Byzantine Generals Problem. Placing results within a Byzantine Fault Tolerant system resolves this.

Multisig Lifetime

The keys for a Validator Set remain valid until its participants change. If a Validator Set adds a new member, and then they leave, the set's historical keys are not reused.

Multisig Handoffs

Once new keys are confirmed for a given Validator Set, they become tracked and the recommended set of keys for incoming coins. The old keys are still eligible to receive coins for a provided grace period, requiring the current Validator Set to track both sets of keys. The old keys are also prioritized for handling outbound transfers, until the end of the grace period, at which point they're no longer eligible to receive coins and they forward all of their coins to the new set of keys. It is only then that validators in the previous instance of the set, yet not the current instance, may unbond their stake.

Vote (message)

coin (Coin): Coin whose key is being voted for.
key (Key): Key being voted on.

Once a key is voted on by every member, it's adopted as detailed above.

3.7 KiB Raw Blame History