Dencun Upgrade Goes Live! Read on Proto Danksharding and more.

Kerala Blockchain Academy
6 min readMar 14, 2024

By Sumi Maria Abraham, Research and Development Engineer,

Dencun, the biggest upgrade since the Merge, has just gone live on the Ethereum network. After Dencun launched, the price of ETH slumped 3.2% from $4,076 to $3,949.

The Dencun hard fork was successfully activated at Ethereum block 19426589 , proposed on slot 8626178, epoch 269568 , at 13:55 UTC , and finalized at 14:10 UTC. Now the new upgrade is intended to improve the Ethereum blockchain, including lowering fees, non-persistent storage options and improving transaction speed.

What is Dencun ?

Dencun is a name that denotes a set of upgrades to the consensus and execution layers. The consensus layer updates are called Deneb, and the execution layer updates are called Cancun . This is the first major upgrade planned for 2024.

The Dencun network upgrade was successfully activated on the Goerli testnet on January 17, Sepolia on January 30 and Holesky on February 7.

What are the updates included in Dencun ?

The inclusion of a new type of transaction allowing blob spaces has introduced some changes in the basic block structure, as shown below.

Let’s take a look at the changes introduced by the Dencun Upgrade. Dencun upgrade introduces the below changes:

>> EIP-1153Transient storage opcodes: transient storage is a new mechanism introducing private storage associated with a smart contract. The transient storage can be used similarly to the storage except for the fact that transient storage is automatically cleared at the end of a transaction. It is helpful to temporarily hold data during a transaction, which decreases gas expenses. This will benefit L2 solutions like rollups and contract deployment operations where temporary data management is required.

>> EIP-4788Beacon block root in the EVM: Adding an additional field in the header of block: parent_beacon_block_root. This field is 32 bytes, and it stores the hash of the parent beacon block for the given execution block. This allows Beacon Chain’s roots to be accessible to the Ethereum Virtual Machine (EVM), thereby allowing smart contracts direct access to the consensus state. This bridges the communication gap between the execution and consensus layers by allowing access to the Ethereum consensus layer with minimised trust.

>> EIP-4844Shard Blob Transactions: Introduces a new type of “blob-carrying transactions” that contain a large amount of data that EVM cannot directly access. The blob transaction processing uses a cryptographic commitment technique called KZG scheme which is an alternative to Merkle proofs. The KZG fits a polynomial equation to a given data. The commitment evaluates the polynomial at some secret data points. A prover would fit the same polynomial over the data and evaluate it at the same values, checking that the result is the same. The commitment will be accessible to EVM and persist, whereas the transaction data in the blobs will be periodically pruned. The blobs will be stored in the consensus client.

Read more on Proto-Danksharding (EIP-4844) here.

The blob storage will be measured in terms of blob gas, which is cheaper than gas. The blob gas has a different set of rules for fee calculation. The block header has two new fields:

  • blob_gas_used denotes the total amount of blob gas consumed by the transactions within the block.
  • excess_blob_gas is a running total of blob gas consumed in excess of the target prior to the block. This is needed to compute the blob gas base fee.

For blob-carrying transactions, the TransactionType is BLOB_TX_TYPE. It has new fields max_fee_per_blob_gas for calculating blob gas fees and blob_versioned_hashes, representing a list of hash outputs from kzg_to_versioned_hash.

>> EIP-5656- MCOPY — A new Memory copying instruction. Currently copying data from one location to another in memory is done by MSTORE and MLOAD opcodes. MCOPY combines both functionalities, and it can efficiently handle copying between non-overlapping areas of memory and overlapping areas, as well as move memory backwards. It helps reduce the number of instructions for memory copy operations, thereby saving gas.

>>EIP-6780: SELFDESTRUCT updations. SELFDESTRUCT was an opcode used to clear unwanted data from the Ethereum state. On invoking the selfdestruct function, the contract balance will be transferred to a target address, associated storage and code will be erased, and nonce will be reset to 0. However, it was moved to a deprecated status later, owing to some attacks that misused the selfdestruct functionalities. There are still contracts which use selfdestruct. As per this upgrade, if the contract does not reference SELFDESTRUCT in the same transaction as creation, only the funds are sent to the target, while the code, storage, and nonce are not altered.

>> EIP-7044 -Perpetually Valid Signed Voluntary Exits: If a validator wishes to exit, it is done by sending a “voluntary exit message” (VEM) signed with the validator’s signing key to the consensus client. In the case of delegated staking, the signing keys (used while performing validator tasks) will be with a validator operator (the entity which manages the validators) and the withdrawal keys (required to claim the staked deposit) will be with the Staker who is funding a specific validator. The validator operator normally provides pre-signed voluntary exits for the validators they operate, and these will be sent to the stakers corresponding to each validator. These signed voluntary exits were valid up-to only two upgrades. EIP-7044 makes voluntary exits valid even after the forever. This helps simplify the staking operations and opens design options for handling validator exits via smart contracts.

>> EIP-7045- Increase Max Attestation Inclusion Slot: The attestations (votes) of validators are used to decide the fork-choice rule LMD GHOST used in Ethereum. Attestations for a specific slot must be included in a block within a specific time period, after which it is considered invalid. This time period is extended by this upgrade so that more validator attestations will be considered before deciding on a fork choice. The more the attestations, the more will be the efficiency of LMD-GHOST.

>> EIP-7514 -Add Max Epoch Churn Limit: The churn limit restricts the number of validators that can enter or exit the Ethereum network during an epoch. This is adjusted in such a way that the proof of stake consensus works in a stable manner. The churn limit was a variable which is adjusted based on the number of active validators. This EIP sets Ethereum’s churn limit as 8, thereby decreasing the growth of the validator set.

>> EIP-7516- BLOBBASEFEE opcode: Add a BLOBBASEFEE (0x4a) instruction that returns the value of the blob base-fee of the current block it is executing in.

Overall the updates are aimed at helping L2, reducing the transaction fee, make Ethereum more affordable, support validator operations in a user-friendly way.

To conclude..

The Dencun Upgrade signifies a massive jump in Ethereum’s attempts to become a scalable and cost-effective public blockchain. The blob-carrying transactions introduced by proto-dank sharding confirm the role of Ethereum as a settlement layer for L2 protocols. This along with the other updates collectively is expected to cause an increase in the userbase of Ethereum.

References

[1] https://blog.ethereum.org/2024/02/27/dencun-mainnet-announcement

[2] https://consensys.io/blog/

[3] https://www.coindesk.com/

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