wizard: normalize bip32 derivation path

so that what gets put in storage is "canonical"
(from now on... we could storage upgrade existing wallets
but it's not critical)

electrum/base_wizard.py

@@ -32,7 +32,7 @@ from typing import List, TYPE_CHECKING, Tuple, NamedTuple, Any
 from . import bitcoin
 from . import keystore
 from . import mnemonic
-from .bip32 import is_bip32_derivation, xpub_type
+from .bip32 import is_bip32_derivation, xpub_type, normalize_bip32_derivation
 from .keystore import bip44_derivation, purpose48_derivation
 from .wallet import (Imported_Wallet, Standard_Wallet, Multisig_Wallet,
                      wallet_types, Wallet, Abstract_Wallet)
@@ -340,6 +340,7 @@ class BaseWizard(object):
             return
         if purpose == HWD_SETUP_NEW_WALLET:
             def f(derivation, script_type):
+                derivation = normalize_bip32_derivation(derivation)
                 self.run('on_hw_derivation', name, device_info, derivation, script_type)
             self.derivation_and_script_type_dialog(f)
         elif purpose == HWD_SETUP_DECRYPT_WALLET:
@@ -452,6 +453,7 @@ class BaseWizard(object):
 
     def on_restore_bip39(self, seed, passphrase):
         def f(derivation, script_type):
+            derivation = normalize_bip32_derivation(derivation)
             self.run('on_bip43', seed, passphrase, derivation, script_type)
         self.derivation_and_script_type_dialog(f)
 

electrum/bip32.py

@@ -292,6 +292,8 @@ def convert_bip32_path_to_list_of_uint32(n: str) -> List[int]:
             x = x[:-1]
             prime = BIP32_PRIME
         if x.startswith('-'):
+            if prime:
+                raise ValueError(f"bip32 path child index is signalling hardened level in multiple ways")
             prime = BIP32_PRIME
         child_index = abs(int(x)) | prime
         if child_index > UINT32_MAX:
@@ -300,12 +302,36 @@ def convert_bip32_path_to_list_of_uint32(n: str) -> List[int]:
     return path
 
 
+def convert_bip32_intpath_to_strpath(path: List[int]) -> str:
+    s = "m/"
+    for child_index in path:
+        if not isinstance(child_index, int):
+            raise TypeError(f"bip32 path child index must be int: {child_index}")
+        if not (0 <= child_index <= UINT32_MAX):
+            raise ValueError(f"bip32 path child index out of range: {child_index}")
+        prime = ""
+        if child_index & BIP32_PRIME:
+            prime = "'"
+            child_index = child_index ^ BIP32_PRIME
+        s += str(child_index) + prime + '/'
+    # cut trailing "/"
+    s = s[:-1]
+    return s
+
+
 def is_bip32_derivation(s: str) -> bool:
     try:
-        if not s.startswith('m/'):
+        if not (s == 'm' or s.startswith('m/')):
             return False
         convert_bip32_path_to_list_of_uint32(s)
     except:
         return False
     else:
         return True
+
+
+def normalize_bip32_derivation(s: str) -> str:
+    if not is_bip32_derivation(s):
+        raise ValueError(f"invalid bip32 derivation: {s}")
+    ints = convert_bip32_path_to_list_of_uint32(s)
+    return convert_bip32_intpath_to_strpath(ints)

electrum/tests/test_bitcoin.py

@@ -9,9 +9,10 @@ from electrum.bitcoin import (public_key_to_p2pkh, address_from_private_key,
                               is_compressed_privkey, EncodeBase58Check,
                               script_num_to_hex, push_script, add_number_to_script, int_to_hex,
                               opcodes)
-from electrum.bip32 import (BIP32Node,
+from electrum.bip32 import (BIP32Node, convert_bip32_intpath_to_strpath,
                             xpub_from_xprv, xpub_type, is_xprv, is_bip32_derivation,
-                            is_xpub, convert_bip32_path_to_list_of_uint32)
+                            is_xpub, convert_bip32_path_to_list_of_uint32,
+                            normalize_bip32_derivation)
 from electrum.crypto import sha256d, SUPPORTED_PW_HASH_VERSIONS
 from electrum import ecc, crypto, constants
 from electrum.ecc import number_to_string, string_to_number
@@ -463,18 +464,34 @@ class Test_xprv_xpub(SequentialTestCase):
     def test_is_bip32_derivation(self):
         self.assertTrue(is_bip32_derivation("m/0'/1"))
         self.assertTrue(is_bip32_derivation("m/0'/0'"))
+        self.assertTrue(is_bip32_derivation("m/3'/-5/8h/"))
         self.assertTrue(is_bip32_derivation("m/44'/0'/0'/0/0"))
         self.assertTrue(is_bip32_derivation("m/49'/0'/0'/0/0"))
+        self.assertTrue(is_bip32_derivation("m"))
+        self.assertTrue(is_bip32_derivation("m/"))
+        self.assertFalse(is_bip32_derivation("m5"))
         self.assertFalse(is_bip32_derivation("mmmmmm"))
         self.assertFalse(is_bip32_derivation("n/"))
         self.assertFalse(is_bip32_derivation(""))
         self.assertFalse(is_bip32_derivation("m/q8462"))
+        self.assertFalse(is_bip32_derivation("m/-8h"))
 
     def test_convert_bip32_path_to_list_of_uint32(self):
         self.assertEqual([0, 0x80000001, 0x80000001], convert_bip32_path_to_list_of_uint32("m/0/-1/1'"))
         self.assertEqual([], convert_bip32_path_to_list_of_uint32("m/"))
         self.assertEqual([2147483692, 2147488889, 221], convert_bip32_path_to_list_of_uint32("m/44'/5241h/221"))
 
+    def test_convert_bip32_intpath_to_strpath(self):
+        self.assertEqual("m/0/1'/1'", convert_bip32_intpath_to_strpath([0, 0x80000001, 0x80000001]))
+        self.assertEqual("m", convert_bip32_intpath_to_strpath([]))
+        self.assertEqual("m/44'/5241'/221", convert_bip32_intpath_to_strpath([2147483692, 2147488889, 221]))
+
+    def test_normalize_bip32_derivation(self):
+        self.assertEqual("m/0/1'/1'", normalize_bip32_derivation("m/0/1h/1'"))
+        self.assertEqual("m", normalize_bip32_derivation("m////"))
+        self.assertEqual("m/0/2/1'", normalize_bip32_derivation("m/0/2/-1/"))
+        self.assertEqual("m/0/1'/1'/5'", normalize_bip32_derivation("m/0//-1/1'///5h"))
+
     def test_xtype_from_derivation(self):
         self.assertEqual('standard', xtype_from_derivation("m/44'"))
         self.assertEqual('standard', xtype_from_derivation("m/44'/"))