15 concepts in the post-merger era of Ethereum will give you a deeper understanding of Ethereum 2.0

At about 14:42 Beijing time on September 15, Ethereum officially completed the merger. Ethereum triggered the merger mechanism at block height 15537393 and produced the first PoS block with a height of 15537394. The Ethereum consensus officially switched from PoW to PoS mechanism.

Ethereum has entered the post-merger era. How much do you know about Ethereum 2.0? This article uses 15 concepts to give you a deep understanding of it.

1. Beacon chain

The beacon chain introduces proof of stake to Ethereum 1.0 and runs in parallel with Ethereum 1.0. The beacon chain is also known as the coordination layer.

The beacon chain has the following functions:

• Assigning responsibilities to validators

• Confirmation checkpoint

• Implementing a protocol-level random number generator (RNG)

• Facilitating the operation of the beacon chain

• Voting to decide the fork chain head

2. Slots

32 Slots = 1 Epoch

1 slot lasts 12 seconds, during which a randomly selected validator proposes a block. There may or may not be a block in each slot. All validators are divided into committees, with one or more separate committees responsible for validating each slot. One validator in the committee will be selected as the aggregator, while the other 127 validators will perform validation. After each Epoch, the validators from each committee are mixed and merged into a new committee. Each committee has at least 128 validators.

3. Epoch

1 Epoch = 32 Slot

1 epoch represents 32 slots and takes about 6.4 minutes.

Epoch plays an important role when it comes to validator queues and finality.

4. Deposit Contract

The deposit contract is the gateway from the smart contract on Ethereum 1.0 to Ethereum 2.0.

The smart contract accepts any transaction with a minimum of 1 ETH and valid input data.

The Ethereum 2.0 beacon node listens to the deposit contract and uses the input data to trust each validator node.

5. Input Data

The input data, also called deposit data, is a user-generated sequence of 842 characters in length.

It represents the validator public key and the withdrawal public key, signed by the validator private key. The input data needs to be added to the transaction and deposit contracts in order to be recognized by the beacon chain.

6. Validator

Validators need to deposit 32 ETH in the validator deposit contract on the Ethereum 1.0 chain. Validator operators must run a validator node. The responsibilities of the validator are to propose blocks and sign proofs. Validators must guarantee at least half of the online time to receive positive returns.

Eligible for activation & estimated activation

Please refer to the explanation of relevant terms about waiting for activation of validators below. The security deposit has been identified by the "Meeting the activation conditions" timestamp of the ETH2 chain. If there is a queue of validators waiting for activation, the estimated activation timestamp needs to be calculated.

7. Unique Index

Each validator receives its own unique index.

8. Current Balance & Effective Balance

The current balance represents the amount of ETH currently held by the validator. The effective balance represents the value calculated from the current balance and is used to determine the size of the reward or penalty received by the validator. The effective balance can never exceed 32 ETH.

To increase the effective balance, the validator requires "effective balance + 1.25 ETH". In other words, if the effective balance is 20 ETH, the current balance needs to be 21.25 ETH to get an effective balance of 21 Ethereum. As shown in the above example, the effective balance will be adjusted when it falls below the threshold of 0.25.

Here is an example of how the effective balance changes:

• If the current balance is 32.00 ETH — the effective balance is 32.00 ETH.

• If the current balance drops from 22.00 ETH to 21.76 ETH — the effective balance will be 22.00 ETH.

• If the current balance increases to 22.25 ETH and the effective balance is 21 ETH, the effective balance increases to 22 ETH.

9. Slasher

Slashers are their own entity, but require a beacon node to receive proofs.

To detect malicious behavior by validators, the slasher iterates through all received proofs until a slashing attack is discovered.

The discovered slashing is broadcast to the network and the next block proposer adds the proof to the block. The block proposer is rewarded for slashing the malicious validator.

However, slashers will not be rewarded.

Punishable offences

Attestation Violation

• Double voting: A validator signs two conflicting attestations in the same epoch.

• Wrap-around voting: A validator signs a proof around another proof.

Proposer Violation

• Double block proposal: A block proposer signs two conflicting blocks for the same slot.

10. Attestation

A vote by an Attester who verifies the validity of a block.

11. Block Proposer

The validator selected by the beacon chain proposes the next block. Each slot can only have one valid block.

12. Block Status

• Proposed block: The block is proposed by the validator through verification.

• Proposed block (Scheduled): The validator is submitting data.

• Missed/Skipped: The proposer did not successfully propose a block within the specified time, so the block was missed.

• Orphaned: To understand this term, let’s look at the following diagram, where numbers 1-9 represent slots.

1. The validator of slot 1 proposes block “a”.

2. The validator of slot 2 proposes block “b”.

3. Slot 4 was missed because the validator did not propose any blocks (e.g. offline).

4. A fork occurs in slot 5/6: Validator (5) proposes a block, but Validator (6) does not receive relevant information (for example, the block does not reach the validator fast enough). So Validator (6) proposes a block based on the latest information seen from Validator (3).

5. The fork selection rule plays a key role here - it determines which chain among the available chains is the canonical chain.

13. Validator Lifecycle

(1) Deposited margin

32 ETH has been deposited into the ETH1 deposit contract, and this state will remain for about 7 hours. This provides security in the event that the ETH1 chain is attacked.

(2) Waiting for activation

Waiting for activation on ETH2.

Before validators can be added to the validator queue, they need to be voted in by other active validators. Voting happens every 4 hours.

• Until there are 327680 active validators in the network, 4 validators can be activated per epoch. For every 65536 (=4 * 16384) additional active validators, the validator activation rate increases by 1 point.

• After that, 5 validators can be activated in each epoch, which requires 327,680 active validators, or 1,125 validators per day.

• To activate 6 validators per epoch, 393,216 active validators are required, or 1,350 validators per day.

• To activate 7 validators per epoch, 458,752 active validators are required, or 1,575 validators per day.

• To activate 8 validators per epoch, 524,288 active validators are required, or 1,800 validators per day.

• To activate 9 validators per epoch, 589,824 active validators are required, or 2,025 validators per day.

• To activate 10 validators per epoch, 655,360 active validators are required, or 2,200 validators per day.

• The number of activations increases with the number of activated validators, and is limited to the set of activated validators divided by 64,000.

(3) Active Validator

The block currently being confirmed and proposed (=block proposer)

The validator will remain active until:

• Their balance is less than 16 ETH (kicked out of the network)

• Voluntary withdrawal

• Confiscated

(4) Slashing Validator

The validator is a malicious validator and will be fined and kicked out of the system.

Penalty is a negative reward (such as offline).

Slashing is a significant penalty (≥ 1/32 of staked balance) and a forced exit… .—— Justin Drake

(5) Exiting Validator

• Kicked out of the network: The validator's balance is lower than the threshold and is kicked out of the network.

• Exit the network: Voluntary exit, the withdrawal key holder can withdraw the current balance of the corresponding validator balance.

14. Finalization

In Ethereum 2.0, at least two-thirds of validators must be honest, so if there are two competing epochs and one-third of the validators decide to act maliciously, they will be punished. The honest ones will be rewarded.

To determine if an epoch is finalized, validators must agree on the two latest epochs in a row (= "proven"), and then all previous epochs can be considered finalized.

The Epoch that was finally confirmed and the Epoch that is being processed at 19:26 Beijing time on September 5

15. Finality issues

If the voting rate of an epoch is less than 66.6% (= participation rate), the epoch cannot be established. As mentioned in the concept of "finality", three consecutive proven epochs are required to achieve finality. As long as the chain cannot reach this state, there is a finality problem.

During the period of finality issues, the validator queue will be paused and new validators cannot join the network, however, inactive validators with a balance less than 16 ETH will be kicked out of the network. This makes the network more stable and has higher participation rates.