LegacyFields

Standard EVM transaction fields

Standard EVM transaction fields used in TxSeismicMetadata for AAD (Additional Authenticated Data) construction.

Definition

@dataclass(frozen=True)
class LegacyFields:
    chain_id: int
    nonce: int
    to: ChecksumAddress | None
    value: int

Fields

Field	Type	Description
chain_id	int	Numeric chain identifier (e.g., 5124 for testnet)
nonce	int	Sender's transaction count
to	ChecksumAddress | None	Recipient address, or None for contract creation
value	int	Amount of wei to transfer

Example

from seismic_web3 import LegacyFields

legacy = LegacyFields(
    chain_id=5124,
    nonce=42,
    to="0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266",
    value=1 * 10**18,  # 1 ETH in wei
)

Notes

• Called "legacy" because these fields are unchanged from standard Ethereum transactions — present in every tx type since pre-EIP-2718

• Does not include gas, gasPrice, or data. These are the standard EVM fields that go into the AAD — gas/gasPrice are excluded because they aren't part of the authenticated context, and data is the plaintext being encrypted (so it can't also be AAD input)

• The AAD also includes SeismicElements (encryption params, block hash, expiry). The node validates these fields before the transaction enters the mempool

See Also

• TxSeismicMetadata — uses LegacyFields

• SeismicElements — Seismic-specific fields (contrast)

• UnsignedSeismicTx — full transaction structure