bip32: add a specific error for invalid inputs

This is not exhaustive, but should be enough to cover the usual type
errors.

Signed-off-by: Antoine Poinsot <darosior@protonmail.com>

Author: darosior

bip32/__init__.py

@@ -1,4 +1,4 @@
-from .bip32 import BIP32, PrivateDerivationError
+from .bip32 import BIP32, PrivateDerivationError, InvalidInputError
 from .utils import BIP32DerivationError, HARDENED_INDEX
 
 __version__ = "0.0.8"
@@ -7,5 +7,6 @@
     "BIP32",
     "BIP32DerivationError",
     "PrivateDerivationError",
+    "InvalidInputError",
     "HARDENED_INDEX",
 ]

bip32/bip32.py

@@ -17,6 +17,11 @@ class PrivateDerivationError(ValueError):
     pass
 
 
+class InvalidInputError(ValueError):
+    def __init__(self, message):
+        self.message = message
+
+
 class BIP32:
     def __init__(self, chaincode, privkey=None, pubkey=None, fingerprint=None,
                  depth=0, index=0, network="main"):
@@ -37,14 +42,21 @@ def __init__(self, chaincode, privkey=None, pubkey=None, fingerprint=None,
                       need this for serialization.
         :param network: Either "main" or "test".
         """
-        assert isinstance(chaincode, bytes)
-        assert privkey is not None or pubkey is not None
+        if network not in ["main", "test"]:
+            raise InvalidInputError("'network' must be one of 'main' or 'test'")
+        if not isinstance(chaincode, bytes):
+            raise InvalidInputError("'chaincode' must be bytes")
+        if privkey is None and pubkey is None:
+            raise InvalidInputError("Need at least a 'pubkey' or a 'privkey'")
         if privkey is not None:
-            assert isinstance(privkey, bytes)
+            if not isinstance(privkey, bytes):
+                raise InvalidInputError("'privkey' must be bytes")
         if pubkey is not None:
-            assert isinstance(pubkey, bytes)
+            if not isinstance(pubkey, bytes):
+                raise InvalidInputError("'pubkey' must be bytes")
         else:
             pubkey = _privkey_to_pubkey(privkey)
+
         self.master_chaincode = chaincode
         self.master_privkey = privkey
         self.master_pubkey = pubkey
@@ -213,6 +225,9 @@ def from_xpriv(cls, xpriv):
 
         :param xpriv: (str) The encoded serialized extended private key.
         """
+        if not isinstance(xpriv, str):
+            raise InvalidInputError("'xpriv' must be a string")
+
         extended_key = base58.b58decode_check(xpriv)
         (network, depth, fingerprint,
          index, chaincode, key) = _unserialize_extended_key(extended_key)
@@ -226,6 +241,9 @@ def from_xpub(cls, xpub):
 
         :param xpub: (str) The encoded serialized extended public key.
         """
+        if not isinstance(xpub, str):
+            raise InvalidInputError("'xpub' must be a string")
+
         extended_key = base58.b58decode_check(xpub)
         (network, depth, fingerprint,
          index, chaincode, key) = _unserialize_extended_key(extended_key)

tests/test_bip32.py

@@ -2,7 +2,9 @@
 import os
 import pytest
 
-from bip32 import BIP32, HARDENED_INDEX, PrivateDerivationError
+from bip32 import (
+    BIP32, HARDENED_INDEX, PrivateDerivationError, InvalidInputError
+)
 
 
 def test_vector_1():
@@ -174,3 +176,7 @@ def test_sanity_checks():
         bip32.get_privkey_from_path([9, 8])
         bip32.get_pubkey_from_path("m/0'/1")
         bip32.get_xpub_from_path("m/10000'/18")
+
+    # We can't create a BIP32 for an unknown network (to test InvalidInputError)
+    with pytest.raises(InvalidInputError, match="'network' must be one of"):
+        BIP32.from_seed(os.urandom(32), network="invalid_net")