eip-4844

https://eips.ethereum.org/EIPS/eip-4844

https://www.eip4844.com/

Parameters

• BLOB_TX_TYPE: 0x03
• BYTES_PER_FIELD_ELEMENT: 32 2^5
• FIELD_ELEMENTS_PER_BLOB: 4096 2^12

there 2^17 bytes per blob, 131071 bytes

• BLS_MODULUS: 52435875175126190479447740508185965837690552500527637822603658699938581184513

order of BLS12-381's \mathbb{G_1} and \mathbb{G_2}

• VERSIONED_HASH_VERSION_KZG: 0x01
• POINT_EVALUATION_PRECOMPILE_ADDRESS: 0x0A

BLS12-381 的验证 pair 的预编译合约地址

• POINT_EVALUATION_PRECOMPILE_GAS: 50000
• MAX_BLOB_GAS_PER_BLOCK: 786432
• TARGET_BLOB_GAS_PER_BLOCK: 393216 = 786432/2
• MIN_BLOB_GASPRICE: 1
• BLOB_GASPRICE_UPDATE_FRACTION: 分母，计算预估 gas 的
• GAS_PER_BLOB: 2^17
• HASH_OPCODE_BYTE: 0x49，blobhash 调用的操纵码
• HASH_OPCODE_GAS: 3
• MIN_EPOCHS_FOR_BLOB_SIDECARS_REQUESTS: 4096

Types aliases

• Blob: [u8; 2^17]
• VersionedHash: Bytes32
• KZGCommitment: Bytes48
• KZGProof: Bytes48

Cryptographic Helpers

def kzg_to_versioned_hash(commitment: KZGCommitment) -> VersionedHash:
    return VERSIONED_HASH_VERSION_KZG + sha256(commitment)[1:]

Blob transaction

[chain_id, nonce, max_priority_fee_per_gas, max_fee_per_gas, gas_limit, to, value, data, access_list, max_fee_per_blob_gas, blob_versioned_hashes, y_parity, r, s]

to can't be nil

• max_fee_per_blob_gas: u256
• blob_versioned_hashes: vec[kzg_to_versioned_hash]

signature

keccak256(BLOB_TX_TYPE || rlp([chain_id, nonce, max_priority_fee_per_gas, max_fee_per_gas, gas_limit, to, value, data, access_list, max_fee_per_blob_gas, blob_versioned_hashes])).

Block Header

• blob_gas_used
• excess_blob_gas

Gas accounting

def calc_data_fee(header: Header, tx: Transaction) -> int:
    return get_total_blob_gas(tx) * get_blob_gasprice(header)

def get_total_blob_gas(tx: Transaction) -> int:
    return GAS_PER_BLOB * len(tx.blob_versioned_hashes)

# MIN_BLOB_GASPRICE * e ** (excess_blob_gas / BLOB_GASPRICE_UPDATE_FRACTION)
def get_blob_gasprice(header: Header) -> int:
    return fake_exponential(
        MIN_BLOB_GASPRICE,
        header.excess_blob_gas,
        BLOB_GASPRICE_UPDATE_FRACTION
    )

Opcode to get versioned hashes

• BLOBHASH 的 opcode 是: HASH_OPCODE_BYTE

输入index，返回 tx.blob_versioned_hashes[index]，超出返回 全0

Point evaluation precompile

def point_evaluation_precompile(input: Bytes) -> Bytes:
    """
    Verify p(z) = y given commitment that corresponds to the polynomial p(x) and a KZG proof.
    Also verify that the provided commitment matches the provided versioned_hash.
    """
    # The data is encoded as follows: versioned_hash | z | y | commitment | proof | with z and y being padded 32 byte big endian values
    assert len(input) == 192
    versioned_hash = input[:32]
    z = input[32:64]
    y = input[64:96]
    commitment = input[96:144]
    proof = input[144:192]

    # Verify commitment matches versioned_hash
    assert kzg_to_versioned_hash(commitment) == versioned_hash

    # Verify KZG proof with z and y in big endian format
    assert verify_kzg_proof(commitment, z, y, proof)

    # Return FIELD_ELEMENTS_PER_BLOB and BLS_MODULUS as padded 32 byte big endian values
    return Bytes(U256(FIELD_ELEMENTS_PER_BLOB).to_be_bytes32() + U256(BLS_MODULUS).to_be_bytes32())