build_seismic_typed_data

Build eth_signTypedData_v4 payload for TxSeismic

Build a JSON-serializable EIP-712 typed-data payload for a Seismic transaction.

This function exists primarily for parity with the TypeScript client, where eth_signTypedData_v4 is used by browser wallets like MetaMask. In Python you'll typically sign transactions directly with sign_seismic_tx_eip712, but this function is available when you need the raw typed-data structure (e.g. sending it to a frontend for wallet signing).

Signature

def build_seismic_typed_data(tx: UnsignedSeismicTx) -> dict[str, Any]

Parameters

Parameter	Type	Required	Description
tx	UnsignedSeismicTx	Yes	The unsigned Seismic transaction

Returns

Type	Description
dict[str, Any]	Dict with keys types, primaryType, domain, message

Output structure

The returned dictionary follows the eth_signTypedData_v4 format:

{
  "types": {
    "EIP712Domain": [
      { "name": "name",              "type": "string"  },
      { "name": "version",           "type": "string"  },
      { "name": "chainId",           "type": "uint256" },
      { "name": "verifyingContract", "type": "address" }
    ],
    "TxSeismic": [
      { "name": "chainId",          "type": "uint64"   },
      { "name": "nonce",            "type": "uint64"   },
      { "name": "gasPrice",         "type": "uint128"  },
      { "name": "gasLimit",         "type": "uint64"   },
      { "name": "to",               "type": "address"  },
      { "name": "value",            "type": "uint256"  },
      { "name": "input",            "type": "bytes"    },
      { "name": "encryptionPubkey", "type": "bytes"    },
      { "name": "encryptionNonce",  "type": "uint96"   },
      { "name": "messageVersion",   "type": "uint8"    },
      { "name": "recentBlockHash",  "type": "bytes32"  },
      { "name": "expiresAtBlock",   "type": "uint64"   },
      { "name": "signedRead",       "type": "bool"     }
    ]
  },
  "primaryType": "TxSeismic",
  "domain": {
    "name": "Seismic Transaction",
    "version": "2",
    "chainId": 1946,
    "verifyingContract": "0x0000000000000000000000000000000000000000"
  },
  "message": {
    "chainId": 1946,
    "nonce": 42,
    "gasPrice": 20000000000,
    "gasLimit": 100000,
    "to": "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266",
    "value": 1000000000000000000,
    "input": "0xabcd...",
    "encryptionPubkey": "0x02...",
    "encryptionNonce": 12345,
    "messageVersion": 2,
    "recentBlockHash": "0x1234...",
    "expiresAtBlock": 12345678,
    "signedRead": false
  }
}

Field encoding

message values

• Numeric fields — integers (not hex strings)

• Address fields — checksummed 0x-prefixed hex strings

• Bytes fields (input, encryptionPubkey, recentBlockHash) — 0x-prefixed hex strings

• encryptionNonce — the 12-byte nonce converted to an integer via int.from_bytes(…, "big")

• to — becomes the zero address when tx.to is None

domain

• name — "Seismic Transaction"

• version — "2" (matches message_version)

• chainId — numeric chain identifier

• verifyingContract — zero address (signing happens off-chain)

primaryType

Always "TxSeismic".

Example

from seismic_web3 import build_seismic_typed_data
import json

typed_data = build_seismic_typed_data(unsigned_tx)
print(json.dumps(typed_data, indent=2))

Notes

• The hash computed from this data matches eip712_signing_hash(tx)

• The returned dict is JSON-serializable (no Python-specific types)

Warnings

• If tx.to is None, it's encoded as the zero address

• All bytes fields must be 0x-prefixed hex strings

• Ensure numeric values fit in their declared EIP-712 types (e.g. uint64)

See Also

• sign_seismic_tx_eip712 — signs using this data internally

• eip712_signing_hash — computes hash from typed data

• domain_separator — domain component

• struct_hash — message component

• UnsignedSeismicTx — input transaction type