Bytes32

Fixed-size 32-byte value type

Exactly 32 bytes — used for hashes, AES keys, and similar values.

Overview

Bytes32 is a fixed-size byte type that validates its length at construction time. It's used throughout the SDK for values that must be exactly 32 bytes, such as block hashes, AES-GCM keys, and Keccak-256 hashes.

Definition

class Bytes32(HexBytes):
    """Exactly 32 bytes — used for hashes, AES keys, and similar values."""
    _size = 32

Inheritance

• Inherits from HexBytes (from the hexbytes package)

• HexBytes itself inherits from Python's bytes type

• Fully compatible with any API expecting bytes

Construction

Bytes32 can be constructed from:

• Hex strings (with or without "0x" prefix)

• Raw bytes objects

• Integer values

Parameters

Parameter	Type	Required	Description
val	bytes | str | int	Yes	The value to convert to 32 bytes

Raises

• ValueError - If the resulting length is not exactly 32 bytes

Examples

From Hex String

from seismic_web3 import Bytes32

# With 0x prefix
block_hash = Bytes32("0x1234567890abcdef" + "0" * 48)

# Without 0x prefix
key = Bytes32("1234567890abcdef" + "0" * 48)

From Raw Bytes

import os
from seismic_web3 import Bytes32

# Generate random 32 bytes
random_key = Bytes32(os.urandom(32))

From Integer

from seismic_web3 import Bytes32

# Convert integer to 32-byte big-endian representation
value = Bytes32(12345)

Length Validation

from seismic_web3 import Bytes32

# This will raise ValueError
try:
    invalid = Bytes32("0x1234")  # Too short
except ValueError as e:
    print(e)  # "Bytes32: expected 32 bytes, got 2"

Methods

to_0x_hex()

Returns the hex string representation with "0x" prefix.

key = Bytes32(os.urandom(32))
hex_str = key.to_0x_hex()  # "0xabcd...ef"

Properties

• Immutable - Cannot be modified after construction

• Hashable - Can be used as dictionary keys or in sets

• Compatible with bytes - Passes isinstance(x, bytes) checks

Notes

• All Bytes32 instances have len() == 32

• Type validation happens at construction time

• Compatible with all web3.py APIs expecting bytes

• Commonly used for block hashes in SeismicElements

See Also

• PrivateKey - 32-byte private key (subclass of Bytes32)

• CompressedPublicKey - 33-byte public key

• EncryptionNonce - 12-byte nonce

• SeismicElements - Uses Bytes32 for recent_block_hash