At present, Ethereum has become the most widely used public chain, with the latest market value reaching 271 billion US dollars (on December 6th), which is comparable to the value of a large Internet company. The ecological development is huge, and many projects have been grafted onto the Ethereum public chain for verification. , but I have to say that the speed is far from the high-speed and timely verification required today.
Currently, Ethereum blocks require 64 to 95 slots (~15 minutes) to achieve finality. This is reasonable and a compromise on the decentralization/finality time/cost curve: 15 minutes is not too long and is comparable to confirmation times on existing exchanges, and it allows users to Even though there are a large number of validators because the deposit size is 32 ETH (instead of the 1500 ETH required in the previous period). However, there are still good reasons to reduce the finality time to one slot.
First, let’s understand how Ethereum staking currently works and its basis:
Ethereum’s LMD GHOST + Casper FFG consensus is a compromise between the two mainstream consensus algorithms popular in proof-of-stake blockchains:
Chain-based consensus algorithms: A message (block) is generated every slot (a preset time interval, such as 12 seconds in Ethereum). Chain-based consensus algorithms maximize the number of participants and reduce the load on the chain, but are prone to forks and have no concept of finality.
Traditional BFT (Byzantine Fault Tolerance) consensus algorithm: In each slot, in addition to a validator generating a block, each validator generates two messages ("attestation", translator's note: that is, "witness"), and the block of a slot achieves irreversible "finality" before the start of the next slot. The traditional BFT consensus algorithm minimizes the time to achieve finality, but at the cost of high chain load and only supporting a small number of participants.
Unlike pure chain-based systems, the Ethereum consensus algorithm performs thousands of witness votes on the chain head in parallel in each slot. Every epoch (32 slots, or 6.4 minutes), all active validators have the opportunity to attest once. After two epochs, the Casper FFG finality tool finalizes the block, and from then on, rolling back the block requires at least one-third of the validators to destroy their staked deposits: the cost of the attack will exceed 4 million ETH. This is different from pure traditional BFT systems, which achieve finalization after one slot.
What are the key issues we need to solve to achieve single slot finality?
There are three key questions:
Developing a definitive consensus algorithm: We are not likely to accept Tendermint or other existing BFT algorithms, because we value the fact that the blockchain can still maintain liveness even when more than 1/3 of validators are offline (which traditional BFT cannot provide). We need to add a fork choice rule, inactivity leak, and recovery mechanism to achieve this liveness. Ideally, we can get the best safety: when the network is in sync, the fault tolerance is 1/2−ϵ; when the network is out of sync, the fault tolerance is 1/3−ϵ.
Determine the optimal aggregation strategy. For as high N as possible, we want to aggregate signatures from N validators and package them into a single block, with a node overhead we are willing to accept.
Determine the economic model for validators. Despite improvements in the aggregation and final validation steps, Ethereum with finality per slot may end up supporting a theoretical upper limit of the number of validators that is smaller than Ethereum currently supports. If this number ends up being lower than the number of validators that want to participate, how do we limit participation, and what sacrifices will we make?
What projects are working on achieving single slot finality?
Currently, the most authoritative and project with the greatest advantages is SSFINALITY, which has great highlights.
SSF, the full name of Single slot Finality, is a single-slot blockchain operating platform. It has a huge blockchain ecosystem and will end the hybrid chain state. It independently builds the SBFT language and uses the LMD Ghost fork algorithm to select the main chain. It uses Casper FFG to finalize the checkpoint. Casper the Friendly Finality Gadget's voting on the shard chain state (Crosslink) uses the deep participation of FORK, and short-term improvements in fork selection (such as view-merge) may also have an impact on the work of SSF fork selection; aggregate work 6426 committees 256 verifications and 16 designated aggregators, and each of them combines all the signatures they see to form an aggregate signature (96 bytes + 256 bit fields). At the same time, the fork choice patch is merged with the view in a timely manner, which perfectly completes the security issues after the speed increase and solves the improvement of Ethereum transmission from 15 minutes to 16 seconds!
The SSFINALITY project is valued at 2 billion US dollars. You can check the official media and find that the A round of financing has successively obtained investments of nearly 6 senior capitals totaling 17 million US dollars for the development of GAMEFI DEX and other ecosystems, including the old American hedge fund Tiger Fund, Binance investment project DODO CRYPTO, and Binance's early investment institution Black Hole Crypto, Black Hole Capital, Coinmaketcap's investment institution LXID FINANCE, Cosmos' investment institution North Venture and AXS's investment institution BT LABS, etc.
SSFINALITY's strength should not be underestimated and will surely attract market praise. You can pay close attention to the progress of the project. At the same time, the SSF currency exchange and smart price display functions have been launched before 9 am on December 6th. Please pay attention and participate.
