Proto-Danksharding
Proto-Danksharding is the first phase of Ethereum's sharding roadmap, implemented via EIP-4844 and activated in the Dencun upgrade in March 2024, which introduces blob-carrying transactions and the KZG commitment infrastructure needed for full Danksharding, while initially limiting throughput to a small number of blobs per block without yet implementing data availability sampling.
The name Proto-Danksharding reflects its role as a precursor: it is not the complete Danksharding design but a stepping stone that delivers most of the immediate cost reduction benefits while deferring the more technically complex components — data availability sampling and distributed block building — to later upgrades.
Proto-Danksharding achieves its cost reduction by creating a separate cheap data lane (blobs) distinct from the permanent calldata lane, as described in the Blob Transaction entry. But it achieves this without the full DAS mechanism: in the current implementation, nodes still download all blobs, just temporarily rather than permanently. The consensus layer's beacon nodes are responsible for storing and propagating blobs for approximately two weeks.
The critical infrastructure that Proto-Danksharding deploys for the future is the KZG commitment scheme. KZG (Kate-Zaverucha-Goldberg) is a polynomial commitment that allows a prover to demonstrate that a piece of data matches a short cryptographic commitment without revealing the full data, using a trusted setup ceremony to establish the necessary public parameters. The KZG trusted setup ceremony for Ethereum involved over 140,000 contributors submitting randomness, making it the largest such ceremony in cryptographic history and ensuring that as long as any single contributor kept their randomness secret, the setup is secure.
KZG commitments are the cryptographic primitive that enables DAS in full Danksharding. Each blob is committed using a KZG polynomial commitment, and the DAS sampling process relies on the ability to prove that specific chunks of a blob are correct fragments of the committed polynomial. By deploying this commitment scheme now, Ethereum establishes the cryptographic foundation that full Danksharding's sampling and verification logic will build on.
For U.S. developers building rollups on Ethereum, Proto-Danksharding and EIP-4844 represent the most significant reduction in data posting costs in Ethereum's history. The 90%-plus fee reduction for L2 users accelerated adoption of Ethereum rollups as the dominant paradigm for scaling, and the subsequent growth of Base, Arbitrum, OP Mainnet, and zkSync following the Dencun upgrade can be directly attributed to the economics enabled by blob transactions.