compute_deposit_data_root

Compute SSZ-style deposit data root for validator deposits

Compute the 32-byte deposit data root hash (SHA-256 SSZ hash tree root) for validator deposits. This value must be passed as the deposit_data_root parameter when calling deposit().

Signature

def compute_deposit_data_root(
    *,
    node_pubkey: bytes,
    consensus_pubkey: bytes,
    withdrawal_credentials: bytes,
    node_signature: bytes,
    consensus_signature: bytes,
    amount_gwei: int,
) -> bytes

All parameters are keyword-only.

Parameters

Parameter	Type	Bytes	Description
node_pubkey	bytes	32	ED25519 public key for node identity
consensus_pubkey	bytes	48	BLS12-381 public key for consensus
withdrawal_credentials	bytes	32	Use make_withdrawal_credentials
node_signature	bytes	64	ED25519 signature over deposit data
consensus_signature	bytes	96	BLS12-381 signature over deposit data
amount_gwei	int	—	Deposit amount in gwei (e.g. 32 * 1000000000)

Returns

bytes — 32-byte deposit data root hash.

Raises ValueError if any byte-length parameter has the wrong size.

How It Works

The function computes the SSZ hash tree root, mirroring the on-chain verification in DepositContract.sol:

pubkey_root         = SHA256(node_pubkey + SHA256(consensus_pubkey + pad_16))
signature_root      = SHA256(SHA256(node_sig) + SHA256(SHA256(con_sig[:64]) + SHA256(con_sig[64:] + pad_32)))
deposit_data_root   = SHA256(SHA256(pubkey_root + withdrawal_credentials) + SHA256(amount_le8 + pad_24 + signature_root))

Where amount_le8 is the gwei value encoded as 8-byte little-endian, and pad_N extends data to chunk boundaries.

Example

from seismic_web3 import compute_deposit_data_root, make_withdrawal_credentials

withdrawal_credentials = make_withdrawal_credentials(
    "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266"
)

root = compute_deposit_data_root(
    node_pubkey=bytes(32),
    consensus_pubkey=bytes(48),
    withdrawal_credentials=withdrawal_credentials,
    node_signature=bytes(64),
    consensus_signature=bytes(96),
    amount_gwei=32 * 1000000000,
)

print(root.hex())  # 32-byte hex string

See Also

• make_withdrawal_credentials — Build the withdrawal_credentials input

• Deposit Contract — ABI, address, and deposit requirements

• deposit — Namespace method for making deposits