#explain-card ## Overview The **[[Dencun upgrade|Dencun Upgrade]]** (also known as Cancun-Deneb) is a significant [[Ethereum]] network upgrade that went live on March 13, 2024. Its most notable feature is the introduction of **Proto-Danksharding** through **Ethereum Improvement Proposal 4844 (EIP-4844)**. This [[EIP]] aims to drastically reduce transaction fees for [[Layer 2]] [[Rollup|rollups]] and improve Ethereum's overall scalability by introducing a new way for rollups to post data to the Ethereum mainnet. - **Problem Solved:** High data posting costs for Layer 2 rollups on Ethereum [[Layer 1]]. Rollups previously used `CALLDATA` to submit transaction data, which is expensive as it's processed by all Ethereum [[Node|nodes]] and stored on-chain indefinitely. EIP-4844 provides a cheaper, more efficient alternative. - **Value Proposition:** Significantly lowers Layer 2 transaction costs, making [[DApp|dApps]] on rollups more affordable and enhancing Ethereum's competitiveness as a scalable blockchain. - **Status:** Live on Ethereum since March 13, 2024. ## Key Mechanisms of EIP-4844 (Proto-Danksharding) EIP-4844 introduces several key components: 1. \*\*Blob-Carrying Transactions (Blobs): - A new transaction type that allows Layer 2 rollups to post large amounts of data (up to ~128 KB per blob, with a target of 3 blobs and a max of 6 blobs per [[Block|block]] initially) to Ethereum in a dedicated, temporary storage space called "blobspace." - Blobs are separate from `CALLDATA` and are not accessed by the [[EVM]] (Ethereum Virtual Machine). - Data in blobs is only guaranteed to be available for a limited period (e.g., ~18 days, pruned by [[Consensus|consensus]] layer clients), which is sufficient for rollups to retrieve and verify it, but avoids long-term storage costs on Layer 1. 2. **New Fee Market for Blobs:** - Blobspace has its own fee market, separate from the regular [[Gas|gas]] market for `CALLDATA` and EVM execution. This means the cost of posting blobs is independent of Ethereum's mainnet [[Gas price|gas prices]]. - Fees for blobs are expected to be significantly lower than using `CALLDATA`. 3. \*\*KZG Commitments (Kate-Zaverucha-Goldberg Commitments): - Cryptographic commitments used to verify the availability of blob data without requiring nodes to download entire blobs. This is a step towards full Danksharding, where data availability sampling (DAS) will allow nodes to verify large amounts of data with minimal overhead. ## Impact and Benefits - **Reduced Layer 2 Fees:** The primary benefit is a substantial reduction in the cost for users transacting on Layer 2 rollups, as the data fees paid by rollups to Ethereum L1 decrease significantly. - **Improved Ethereum Scalability:** By making rollups cheaper and more efficient, Dencun helps Ethereum scale its transaction throughput capacity. - **Path to Full Danksharding:** Proto-Danksharding implements many of the transaction formats, cryptographic schemes (KZG commitments), and logic that will be used in full Danksharding, which promises even greater scalability. - **Enhanced Data Availability:** While temporary, blobs provide a dedicated and cost-effective channel for data availability for rollups. ## Other EIPs in Dencun Besides EIP-4844, the Dencun upgrade included other EIPs focused on various improvements, such as EVM enhancements and minor adjustments to gas costs for specific operations. Key ones include: - EIP-1153: Transient storage opcodes - EIP-4788: Beacon block root in the EVM - EIP-5656: MCOPY - Memory copying instruction - EIP-6780: SELFDESTRUCT only in same transaction ## Related Concepts - Ethereum - Gas - [[The Merge]] (as a precursor to further scaling upgrades)