def from_xpub(
xpub: str,
xpub_type: Optional[XpubType] = None,
path: Optional[str] = None,
) -> 'HDKey':
"""
Instantiate an HDKey from an xpub. Populates all possible fields
Args:
xpub (str): the xpub
path (str): the path if it's known. useful for calling derive_path
Returns:
(HDKey): the key object
May raise:
- XPUBError if there is a problem with decoding the xpub
"""
xpub_bytes = b58decode(xpub)
if len(xpub_bytes) < 78:
raise XPUBError(f'Given XPUB {xpub} is too small')
try:
pubkey = PublicKey(xpub_bytes[45:78])
except ValueError as e:
raise XPUBError(str(e)) from e
result = _parse_prefix(xpub_bytes[0:4])
if not result.is_public:
raise XPUBError('Given xpub is an extended private key')
if result.network != 'mainnet':
raise XPUBError('Given xpub is not for the bitcoin mainnet')
hint = result.hint
if xpub_type is not None and xpub_type.matches_prefix(
xpub[0:4]) is False:
# the given type does not match the prefix, re-encode with correct pref
new_xpub = bytearray()
new_xpub.extend(xpub_type.prefix_bytes())
new_xpub.extend(xpub_bytes[4:])
new_xpub_bytes = new_xpub
hint = xpub_type.prefix()
xpub = b58encode(bytes(new_xpub_bytes)).decode('ascii')
return HDKey(
path=path,
network=result.network,
depth=xpub_bytes[4],
parent_fingerprint=xpub_bytes[5:9],
index=int.from_bytes(xpub_bytes[9:13], byteorder='big'),
parent=None,
chain_code=xpub_bytes[13:45],
fingerprint=hash160(pubkey.format(COMPRESSED_PUBKEY))[:4],
xpriv=None,
xpub=xpub,
privkey=None,
pubkey=pubkey,
hint=hint,
)
def from_xpub(xpub: str, path: Optional[str] = None) -> 'HDKey':
"""
Instantiate an HDKey from an xpub. Populates all possible fields
Args:
xpub (str): the xpub
path (str): the path if it's known. useful for calling derive_path
Returns:
(HDKey): the key object
May raise:
- XPUBError if there is a problem with decoding the xpub
"""
xpub_bytes = b58decode(xpub)
if len(xpub_bytes) < 78:
raise XPUBError(f'Given XPUB {xpub} is too small')
try:
pubkey = PublicKey(xpub_bytes[45:78])
except ValueError as e:
raise XPUBError(str(e)) from e
result = _parse_prefix(xpub_bytes[0:4])
if not result.is_public:
raise XPUBError('Given xpub is an extended private key')
return HDKey(
path=path,
network=result.network,
depth=xpub_bytes[4],
parent_fingerprint=xpub_bytes[5:9],
index=int.from_bytes(xpub_bytes[9:13], byteorder='big'),
parent=None,
chain_code=xpub_bytes[13:45],
fingerprint=hash160(pubkey.format(COMPRESSED_PUBKEY))[:4],
xpriv=None,
xpub=xpub,
privkey=None,
pubkey=pubkey,
hint=result.hint,
)
def _child_from_xpub(self, index: int, child_xpub: str) -> 'HDKey':
"""
Returns a new HDKey object based on the current object and the new
child xpub. Don't call this directly, it's for child derivation.
Args:
index (int): the index of the child
child_xpub (str): the child's xpub
Returns
HDKey: the new child object
"""
path: Optional[str]
if self.path is not None:
path = '{}/{}'.format(self.path, str(index))
else:
path = None
xpub_bytes = b58decode(child_xpub)
pubkey = xpub_bytes[45:78]
result = _parse_prefix(xpub_bytes[0:4])
if not result.is_public:
raise XPUBError('Given xpub is an extended private key')
return HDKey(
path=path,
network=result.network,
depth=xpub_bytes[4],
parent_fingerprint=xpub_bytes[5:9],
index=int.from_bytes(xpub_bytes[9:13], byteorder='big'),
parent=self,
chain_code=xpub_bytes[13:45],
fingerprint=hash160(pubkey)[:4],
xpriv=None,
xpub=child_xpub,
privkey=None,
pubkey=PublicKey(pubkey),
hint=result.hint,
)
