def derivation(self, chain_code: bytes,
child_index: int) -> Tuple["Secp256k1Deriv", bytes]:
if child_index < 0 or child_index >= 2**31:
raise Exception("invalid child index")
I = utils.hmac512(chain_code,
self.get_public_bytes() + utils.tb(child_index, 4))
return (self.__class__(self.derive(Secp256k1Priv(I[0:32]))), I[32:])
def hardened_derivation(self, chain_code: bytes,
child_index: int) -> Tuple["ED25519Priv", bytes]:
if child_index < 0 or child_index >= 2**31:
raise Exception("invalid hardened child index")
I = utils.hmac512(
chain_code, b"\x00" + self.get_private_bytes() +
utils.tb(child_index + 0x80000000, 4))
return (ED25519Priv(I[0:32]), I[32:])
def _to_bytes(self) -> bytes:
ret = utils.tb(self.version.value, 4)
ret += utils.tb(self.depth, 1)
ret += self.parent_fp
cn = self.child_number
if self.hardened:
cn += 0x80000000
ret += utils.tb(cn, 4)
ret += self.chain_code
if self.version == Version.PUBLIC:
if isinstance(self.key, ED25519Pub):
# non standard, invented by this project :(
ret += b"\xff" + self.key.get_public_bytes()
else:
ret += self.key.get_public_bytes()
elif self.version == Version.PRIVATE:
if isinstance(self.key, ED25519Priv):
# non standard, invented by this project :(
ret += b"\xff" + self.key.get_private_bytes()
else:
ret += b"\x00" + self.key.get_private_bytes()
else:
raise Exception("Incorrect version while dumping an XKey")
return ret