---
tags: eip-4844, ethereum
---

# EIP-4844 Spec Notes

- [EIP-4844 Spec](https://eips.ethereum.org/EIPS/eip-4844)
- [Consensus Spec](https://github.com/ethereum/consensus-specs/tree/dev/specs/eip4844)

## EIP-4844: Shared Blob Transactions

### TL;DR

- scale tx size to 2 MB per slot
- separate fee market to lower fees
- temporary scaling relief
- rollups to use blobs instead of calldata due to much lower costs
- bring forward the format that will be used for sharded data but not yet actually sharding it.

### New Transaction Format

- EIP-4844 introduces a new transaction format that would be used in sharding, but not actually sharding those transactions.
- Blob cannot be accessed by EVM execution, only commitment can be accessed
- Format is intended to be forward-compatible with full sharding
- Number of transactions targeted at ~1 MB per block, and limited at ~2 MB instead of ~16MB pr block with sharding

### New Transaction type

- [EIP-2718](https://eips.ethereum.org/EIPS/eip-2718)
- format: single byte `BLOB_TX_TYPE` followed by an SSZ encoding of the `SignedBlobTransaction` container comprising the transaction contents.
- EL verifies the `TransactionNetworkPayload` wrapper (containing `blobs` and `kzgs`) validity against the inner `TransactionPayload` after signature verification.

### Header extension

- new `excess_blobs` field: This is the running total of excess blobs included on chain since this EIP was activated. If the total number of blobs is below the average, excess_blobs is capped at zero.

### CL

- blobs are now referenced in the beacon block body.
- contents of the blobs are propagated separately as a **sidecar**.
- CL peresists the blob for data availability.

### New opcode and precompile

- new opcode `DATAHASH`
- point evaulation precompile: evaluates a proof that a particular blob resolves to a particular value at a point

### Gas price

- Simplified: always return `GAS_PER_BLOB`
- Full: simple independent EIP-1559 style targeting rule to compute the gas cost of the transaction. `excess_blobs` header field data is used to compute the cost.
- Like EIP-1559, it’s a self-correcting formula: as the excess goes higher, the blob_gas increases exponentially, reducing usage and eventually forcing the excess back down

### How rollups work

- rollup submits data into blobs instead of tx calldata

### Dependencies

#### [EIP-2718](https://eips.ethereum.org/EIPS/eip-2718)

> Defines a new transaction type that is an envelope for future transaction types.

#### [EIP-2930](https://eips.ethereum.org/EIPS/eip-2930): Optional access lists

> Adds a transaction type which contains an access list, a list of addresses and storage keys that the transaction plans to access. Accesses outside the list are possible, but become more expensive.

## Consensus Spec

### Beacon Chain

### Fork Logic

- fork epoch

### Networking

- new global topic `beacon_block_and_blobs_sidecar`: propagate new signed and coupled beacon blocks and blob sidecars to all nodes on the network.
- validations MUST pass before forwarding the blob sidecar on the network
- KZG commitments of the blobs are all correctly encoded
- KZG commitments corroespond to the versioned hashes
- sidecar is for the current slot
- blobs are well formated and `BLSFieldElement` in valid range
- KZG proof is correctly encoded compressed BLS G1 Point

### Polynomial Commitments

### Honest Validator