def from_bytes(b):
""" Generates either a HDPrivateKey or HDPublicKey from the underlying
bytes.
The serialization must conform to the description in:
https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#serialization-format
Args:
b (bytes): A byte stream conforming to the above.
Returns:
HDPrivateKey or HDPublicKey: Either an HD private or
public key object, depending on what was serialized.
"""
if len(b) < 78:
raise ValueError("b must be at least 78 bytes long.")
version = int.from_bytes(b[:4], 'big')
depth = b[4]
parent_fingerprint = b[5:9]
index = int.from_bytes(b[9:13], 'big')
chain_code = b[13:45]
key_bytes = b[45:78]
rv = None
if version == HDPrivateKey.MAINNET_VERSION or version == HDPrivateKey.TESTNET_VERSION:
if key_bytes[0] != 0:
raise ValueError("First byte of private key must be 0x00!")
private_key = int.from_bytes(key_bytes[1:], 'big')
rv = HDPrivateKey(key=private_key,
chain_code=chain_code,
index=index,
depth=depth,
parent_fingerprint=parent_fingerprint)
elif version == HDPublicKey.MAINNET_VERSION or version == HDPublicKey.TESTNET_VERSION:
if key_bytes[0] != 0x02 and key_bytes[0] != 0x03:
raise ValueError("First byte of public key must be 0x02 or 0x03!")
public_key = PublicKey.from_bytes(key_bytes)
rv = HDPublicKey(x=public_key.point.x,
y=public_key.point.y,
chain_code=chain_code,
index=index,
depth=depth,
parent_fingerprint=parent_fingerprint)
else:
raise ValueError("incorrect encoding.")
return (rv, b[78:])
