What is the Dencun Upgrade?

Is EIP-4844, or Proto-Danksharding, the first step toward true Ethereum scalability?


  • What is Proto-Danksharding?

  • How do Blobs Work?

  • What is KZG?

  • The Future of Danksharding

  • Summary

Ethereum's roadmap initially included the development of shard-chains, designed to split the blockchain into multiple segments for scalability. However, the inception of Danksharding has changed this focus.

Danksharding introduces a more straightforward approach to scaling Ethereum by utilizing distributed data sampling through “blobs”, removing the complexities of shard-chains. While the full implementation of Danksharding is still years away, Proto-Danksharding is the crucial first step toward this. Both Danksharding and its proto version are aimed toward drastically reducing transaction costs on Layer 2s and elevating Ethereum’s capacity to handle over 100,000 transactions per second (TPS).

What is Proto-Danksharding?

The Dencun upgrade, EIP-4844, or Proto-Danksharding, introduces a more cost-effective method for rollups to integrate data into blocks. Traditionally, rollups utilized "calldata" to post transactions, a process that's relatively expensive because this data is stored on-chain indefinitely, despite rollups only needing it temporarily. Proto-Danksharding's approach involves using "blobs," temporary data attachments to blocks that aren't accessible by the EVM and are set to be automatically purged after roughly 18 days (4096 epochs). In doing so, rollups are able to send data in a more affordable way, translating to lower transaction costs for users.

Source: HackMD
Source: HackMD

How do Blobs Work?

We've touched on blobs above, but in order to go deeper into what they are and how they function, we need to first explain rollups.

Rollups are a scaling solution for Ethereum, bundling multiple transactions off-chain and then committing these to the mainnet. They operate through two core components, data and execution checks. The data component captures the entire sequence of transactions that the rollup processes to change a state on Ethereum. The execution check, on the other hand, involves re-running these transactions by a trusted entity, known as a "prover," to validate the accuracy of the state change.

The transaction data needs to be available long enough for anyone to review and verify it. This ensures any incorrect actions can be spotted and challenged. But once this data has been checked, it's not needed anymore, so storing it indefinitely on-chain is wasteful, becoming redundant and resource-intensive.

Rollups post their commitments to their transaction data on-chain and also share the actual data in blobs. These blobs let provers verify the transactions or flag any issues. Nodes store these blobs temporarily, making sure the data gets around the network and everyone who needs to check it can do so. If we kept this data forever, nodes would bloat quickly and become hard to manage. To prevent this, the data gets deleted from nodes every 18 days. This way, nodes confirm the data was available long enough for a thorough check but don't get overwhelmed. If there's a need to keep the data longer, it can be stored off-chain by rollup operators, users, or anyone else interested.

Source: HackMD
Source: HackMD

What is KZG?

KZG, named after its creators Kate, Zaverucha, and Goldberg, is a cryptographic technique that condenses a large data set (or blob) into a small, verifiable commitment. This is particularly relevant for rollups on Ethereum, where it's crucial to confirm that the data provided by a rollup is accurate and that the rollup isn't acting maliciously.

Here's how it works:

A prover, which could be an entity or a process, re-executes the transactions contained in the data blob to validate the commitment, similar to how transactions are verified on Ethereum using merkle proofs. However, KZG uses a different approach - it applies a polynomial equation to the data, creating a commitment that represents the polynomial evaluated at certain secret points.

When verification is needed, a prover reconstructs the same polynomial from the blob's data and evaluates it at those secret points, ensuring the outcomes match. This method is particularly effective as it aligns with zero-knowledge techniques, which are used in some rollups to increase privacy and efficiency in data verification.

Source: Inevitable Ethereum
Source: Inevitable Ethereum

The Future of Danksharding

Danksharding represents the next big step in Ethereum's scaling roadmap, building on the groundwork laid by Proto-Danksharding. It's set to significantly increase the space on Ethereum, enabling rollups to send more of their transaction data. This capacity boost means Ethereum could support hundreds of rollups, pushing the network towards millions of TPS.

In practical terms, Danksharding will expand the number of blobs attached to each block from 1 in the Proto-Danksharding phase to 64 in full Danksharding. This expansion requires updates in how consensus clients function, enabling them to manage these larger blobs. These adaptations are part of Ethereum's broader roadmap, with many serving multiple objectives beyond Danksharding alone.

For instance, the implementation of proposer-builder separation is crucial for Danksharding. This upgrade separates the roles of block building and proposing among various validators. Furthermore, data availability sampling will also enable the creation of lightweight clients that require minimal historical data storage.


Proto-Danksharding is Ethereum's first solid step toward achieving true scalability. It's paving the way for Danksharding by enabling rollups to incorporate data into blocks more affordably.

Instead of using "calldata" for transactions, Proto-Danksharding introduces data blobs that attach to blocks, offering a temporary storage solution that's not EVM-accessible and is purged after 18 days. This approach reduces costs for rollups, and ultimately lowers transaction fees for users.

Make sure to keep an eye out for the other upgrades coming along the way to full Danksharding.

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