---
tags: epf, ethereum
---

# EPF Dev Update #5

## Quick updates for this week:

- We've finally got our [EIP-4844 Project Proposal](https://github.com/eth-protocol-fellows/cohort-three/blob/master/projects/4844-consensus-client.md). **@0xGabi** and I been having regular catch ups with the Lighthouse team, and we're now both happy with the proposal and have started working on it! :writing_hand:
- Drafted out the Builder API work for EIP-4844 in [this document](https://hackmd.io/@jimmygchen/B1dLR74Io), and we're now working on the spec changes, and will hopefully have some draft PRs for review soon! The sequence diagram below provides a quick summary of the changes required.
- Continue my investigation on getting Lighthouse to work on the [eip4844-interop](https://github.com/Inphi/eip4844-interop) repo. Sean from Lighthouse team has made some further progress on this [branch](https://github.com/realbigsean/eip4844-interop/tree/interop-lighthouse), and I'll be helping with testing. Excited about getting Lighthouse ready for devnet v3!
- Next task on `eip4844-interop` is probably getting a Lighthouse boot node to work, instead of using Prysm as boot node, so we can test out the full functionalities of Lighthouse.

## Builder API changes for Blobs (EIP-4844)

sequenceDiagram
    participant validator
    participant consensus
    participant mev_boost
    Title: Block Proposal with Builder API (EIP-4844)
    validator->>consensus: GET v2/validator/blinded_blocks/{slot}
    consensus->>mev_boost: GET v1/builder/header/{slot}/{parent_hash}/{pubkey}
    mev_boost-->>consensus: GET v1/builder/header/{slot}/{parent_hash}/{pubkey} response
    Note left of mev_boost: add `blob_kzg_commitments` to response (`SignedBuilderBid`)
    consensus-->>validator: GET v2/validator/blinded_blocks/{slot} response
    Note left of consensus: add `blob_kzg_commitments` to response
    Note over validator: include `blob_kzg_commitments` in block and sign the header
    validator->>consensus: POST beacon/blinded_blocks
    consensus->>mev_boost: POST /eth/v1/builder/blinded_blocks
    mev_boost-->>consensus: POST /eth/v1/builder/blinded_blocks response
    Note left of mev_boost: revealed payload will have to include `blobs_sidecar` and kzg proof
    Note over consensus: construct block and broadcast block

One month has passed, and I've absolutely enjoyed the fellowship program so far! Meeting and collaborating with people on the same journey and working closely with devs working on Ethereum has been an amazing experience :slightly_smiling_face: