Remove unncessary requirements for HDWallet derivation (#463)

* Remove unncessary requirements for HDWallet derivation

* Fix type check

Author: cffls

pycardano/crypto/bip32.py

@@ -82,12 +82,12 @@ class HDWallet:
 
     def __init__(
         self,
-        root_xprivate_key: bytes,
-        root_public_key: bytes,
-        root_chain_code: bytes,
-        xprivate_key: bytes,
-        public_key: bytes,
-        chain_code: bytes,
+        root_xprivate_key: Optional[bytes] = None,
+        root_public_key: Optional[bytes] = None,
+        root_chain_code: Optional[bytes] = None,
+        xprivate_key: Optional[bytes] = None,
+        public_key: Optional[bytes] = None,
+        chain_code: Optional[bytes] = None,
         path: str = "m",
         seed: Optional[bytes] = None,
         mnemonic: Optional[str] = None,
@@ -322,28 +322,36 @@ def derive(
         if not isinstance(index, int):
             raise ValueError("Bad index, Please import only integer number!")
 
-        if not self._root_xprivate_key and not self._root_public_key:
-            raise ValueError("Missing root keys. Can't do derivation.")
-
         if hardened:
             index += 2**31
 
         if private:
+            if self._xprivate_key is None:
+                raise ValueError("Missing private key. Can't do private derivation.")
+
             private_node = (
                 self._xprivate_key[:32],
                 self._xprivate_key[32:],
                 self._public_key,
                 self._chain_code,
                 self._path,
             )
-            return self._derive_private_child_key_by_index(private_node, index)
+
+            if any(x is None for x in private_node):
+                raise ValueError(f"None values in private node: {private_node}")
+
+            return self._derive_private_child_key_by_index(private_node, index)  # type: ignore
 
         public_node = (
             self._public_key,
             self._chain_code,
             self._path,
         )
-        return self._derive_public_child_key_by_index(public_node, index)
+
+        if any(x is None for x in public_node):
+            raise ValueError(f"None values in public node: {public_node}")
+
+        return self._derive_public_child_key_by_index(public_node, index)  # type: ignore
 
     def _derive_private_child_key_by_index(
         self, private_pnode: Tuple[bytes, bytes, bytes, bytes, str], index: int

test/pycardano/crypto/test_bip32.py

@@ -387,3 +387,51 @@ def test_is_entropy_wrong_input():
 def test_is_entropy_value_error():
     is_entropy = HDWallet.is_entropy("*(#_")
     assert is_entropy is False
+
+
+def test_non_harden_public_derivation():
+    public_key = bytes.fromhex(
+        "601c86a2310f438079fff07454f4df4ce416bd181d972cd4c4615f15a733ba15"
+    )
+    chain_code = bytes.fromhex(
+        "8a34b66a32c9d2d61d1d7a0e8fcf167efae3fb556af74808cd1ba8a22251c031"
+    )
+    hdwallet = HDWallet(chain_code=chain_code, public_key=public_key)
+    hdwallet = hdwallet.derive(0, private=False, hardened=False)
+    child1 = hdwallet.derive(0, private=False, hardened=False)
+    child2 = hdwallet.derive(1, private=False, hardened=False)
+    child3 = hdwallet.derive(2, private=False, hardened=False)
+
+    assert (
+        child1.public_key.hex()
+        == "b3f354cbdc2837f823c5e0585995d3bd2d6edf1dc9fc8a1a90d01840c519408d"
+    )
+    assert (
+        child2.public_key.hex()
+        == "363aa29a3c93085859310ccddb182abcca18db6f6897a4f936ae82ba0a15af90"
+    )
+    assert (
+        child3.public_key.hex()
+        == "db58a4102f555ccb64a0db45259799cbd42fac14f7f6fd1059557fef3961e2c0"
+    )
+
+
+def test_non_harden_public_derivation_without_pubkey():
+    chain_code = bytes.fromhex(
+        "8a34b66a32c9d2d61d1d7a0e8fcf167efae3fb556af74808cd1ba8a22251c031"
+    )
+    hdwallet = HDWallet(chain_code=chain_code)
+    with pytest.raises(ValueError):
+        hdwallet.derive(0, private=False, hardened=False)
+
+
+def test_non_harden_private_derivation_without_privkey():
+    public_key = bytes.fromhex(
+        "601c86a2310f438079fff07454f4df4ce416bd181d972cd4c4615f15a733ba15"
+    )
+    chain_code = bytes.fromhex(
+        "8a34b66a32c9d2d61d1d7a0e8fcf167efae3fb556af74808cd1ba8a22251c031"
+    )
+    hdwallet = HDWallet(chain_code=chain_code, public_key=public_key)
+    with pytest.raises(ValueError):
+        hdwallet.derive(0, private=True, hardened=False)