diff --git a/cryptnox_cli/command/command.py b/cryptnox_cli/command/command.py
index 0f2d894..affc36c 100644
--- a/cryptnox_cli/command/command.py
+++ b/cryptnox_cli/command/command.py
@@ -55,6 +55,7 @@ def _handle_execution(self, serial_number: int = None) -> int:
         try:
             self.serial_number = self.data.serial
         except AttributeError:
+            # No serial provided in arguments; keep the passed-in serial_number
             pass
         try:
             card = self._cards[self.serial_number]
@@ -65,7 +66,7 @@ def _handle_execution(self, serial_number: int = None) -> int:
             print(f"Error in retrieving information: {error}")
             return -1
 
-        self.run_execute(card)
+        return self.run_execute(card)
 
     def run_execute(self, card) -> int:
         print(f"Using card with serial number {card.serial_number}")
diff --git a/cryptnox_cli/command/erc_token/initialize.py b/cryptnox_cli/command/erc_token/initialize.py
index e2089bb..40c0023 100644
--- a/cryptnox_cli/command/erc_token/initialize.py
+++ b/cryptnox_cli/command/erc_token/initialize.py
@@ -7,10 +7,10 @@
 
 import gzip
 import json
-import urllib
+import urllib.error
+import urllib.parse
 from argparse import Namespace
 from typing import List
-from urllib import parse
 
 import cryptnox_sdk_py
 import requests
@@ -202,7 +202,7 @@ def _token_slots() -> list[str]:
     def _abi() -> str:
         def uri_validator(x):
             try:
-                result = parse.urlparse(x)
+                result = urllib.parse.urlparse(x)
                 return all([result.scheme, result.netloc])
             except Exception:
                 return False
diff --git a/cryptnox_cli/command/eth.py b/cryptnox_cli/command/eth.py
index 3e2673b..d436608 100644
--- a/cryptnox_cli/command/eth.py
+++ b/cryptnox_cli/command/eth.py
@@ -169,6 +169,8 @@ def logs(self):
             endpoint.block_number
         save_to_config(self.card, self.config)
 
+        return None
+
     @staticmethod
     def _get_logs(event) -> List[Dict[str, Any]]:
         min_offset = 0
@@ -256,6 +258,8 @@ def _execute(self, card):
             print(error)
             return -1
 
+        return None
+
     def _get_endpoint(self, card):
         config = get_configuration(card)
 
@@ -311,6 +315,8 @@ def _add(self, card):
         print(f"Contract added to application. Use it with alias:"
               f" {self.data.alias}")
 
+        return None
+
     @staticmethod
     def _list(card) -> int:
         config = get_configuration(card)
@@ -356,6 +362,8 @@ def _functions(self, card):
 
         print(tabulate(tabulate_table, headers=tabulate_header, tablefmt="grid"))
 
+        return None
+
     def _call(self, card):
         config = get_configuration(card)
         try:
@@ -645,3 +653,5 @@ def _send_token(self, card):
         contract.transfer(card, config["endpoint"], config["network"], config["api_key"],
                           self.data.contract, self.data.address, self.data.amount, self.data.price,
                           self.data.limit, derivation)
+
+        return None
diff --git a/cryptnox_cli/command/get_clearpubkey.py b/cryptnox_cli/command/get_clearpubkey.py
index 1f08b29..d715b71 100644
--- a/cryptnox_cli/command/get_clearpubkey.py
+++ b/cryptnox_cli/command/get_clearpubkey.py
@@ -98,6 +98,7 @@ def _execute(self, card) -> int:
                         else:
                             card.derive(key_type, "m/44'/0'/0'")
                     except Exception:
+                        # Best-effort derivation; clear pubkey read below handles failures
                         pass
                     pubkey_bytes = card.get_public_key_clear(derivation, path, compressed)
                     self._print_pubkey_info(key_type, compressed, pubkey_bytes)
diff --git a/cryptnox_cli/command/helper/cards.py b/cryptnox_cli/command/helper/cards.py
index f048b50..532d70d 100644
--- a/cryptnox_cli/command/helper/cards.py
+++ b/cryptnox_cli/command/helper/cards.py
@@ -113,6 +113,7 @@ def refresh(self, remote: bool = False) -> None:
             except cryptnox_sdk_py.exceptions.ReaderException:
                 break
             except cryptnox_sdk_py.exceptions.CryptnoxException:
+                # Card at this index is unreadable; skip it and continue scanning
                 pass
 
             index += 1
@@ -194,7 +195,7 @@ def _open_card(self, index: int, remote: bool = False) -> cryptnox_sdk_py.Card:
                 if test_response:
                     if index in self._cards_by_index:
                         return self._cards_by_index[index]
-            except (BaseException, cryptnox_sdk_py.exceptions.ConnectionException):
+            except (Exception, cryptnox_sdk_py.exceptions.ConnectionException):
                 # Connection is stale, remove it and create new one
                 del _GLOBAL_CONNECTIONS[index]
                 if index in self._cards_by_index:
diff --git a/cryptnox_cli/command/helper/config.py b/cryptnox_cli/command/helper/config.py
index 54c4ee4..439b037 100644
--- a/cryptnox_cli/command/helper/config.py
+++ b/cryptnox_cli/command/helper/config.py
@@ -185,6 +185,7 @@ def write_config(card: cryptnox_sdk_py.Card, section: str, key: str, value: str)
                 print(error)
         return 1
     except AttributeError:
+        # Key not present on the validator instance; fall through to config handling
         pass
 
     try:
diff --git a/cryptnox_cli/command/helper/helper_methods.py b/cryptnox_cli/command/helper/helper_methods.py
index 576e1ce..cd23830 100644
--- a/cryptnox_cli/command/helper/helper_methods.py
+++ b/cryptnox_cli/command/helper/helper_methods.py
@@ -102,5 +102,6 @@ def try_eval(value: str) -> Any:
     try:
         value = ast.literal_eval(value)
     except ValueError:
+        # Not a literal; keep the original string value
         pass
     return value
diff --git a/cryptnox_cli/command/helper/security.py b/cryptnox_cli/command/helper/security.py
index 64081c6..58724b5 100644
--- a/cryptnox_cli/command/helper/security.py
+++ b/cryptnox_cli/command/helper/security.py
@@ -140,6 +140,7 @@ def check(card, check_seed: bool = True) -> bool:
     try:
         result = user_keys.authenticate(card)
     except NotImplementedError:
+        # User-key auth unsupported here; fall back to PIN authentication below
         pass
 
     if not result:
diff --git a/cryptnox_cli/command/seed.py b/cryptnox_cli/command/seed.py
index 2f34f07..a74f110 100644
--- a/cryptnox_cli/command/seed.py
+++ b/cryptnox_cli/command/seed.py
@@ -96,6 +96,7 @@ def _dual_seed(self, card: cryptnox_sdk_py.Card) -> int:
             print(error)
             return -1
         except cryptnox_sdk_py.exceptions.DataValidationException:
+            # Expected when probing dual-seed support without a PIN; safe to proceed
             pass
 
         print("Dual seed generation process starting...")
diff --git a/cryptnox_cli/command/transfer.py b/cryptnox_cli/command/transfer.py
index e0abac1..2859fb2 100644
--- a/cryptnox_cli/command/transfer.py
+++ b/cryptnox_cli/command/transfer.py
@@ -10,10 +10,8 @@
 
 try:
     import enums
-    from wallet import eth as wallet  # noqa: F401
 except ImportError:
     from .. import enums
-    from ..wallet import eth as wallet  # noqa: F401
 
 
 class Transfer(Command):
diff --git a/cryptnox_cli/command/user_keys/authentication.py b/cryptnox_cli/command/user_keys/authentication.py
index 3caa2f4..6309895 100644
--- a/cryptnox_cli/command/user_keys/authentication.py
+++ b/cryptnox_cli/command/user_keys/authentication.py
@@ -21,6 +21,7 @@
         try:
             importlib.import_module("." + submodule, package=__package__)
         except Exception:
+            # Optional submodule unavailable in frozen build; skip it
             pass
 else:
     # When running normally, dynamically discover submodules
@@ -155,6 +156,7 @@ def delete(name: str, card: cryptnox_sdk_py.Card, puk: str) -> bool:
     try:
         user_key.delete()
     except user_key_base.UserKeyException:
+        # Best-effort local key removal; proceed to delete it from the card
         pass
 
     card.user_key_delete(user_key.slot_index, puk)
diff --git a/cryptnox_cli/command/user_keys/hello/windows_hello.py b/cryptnox_cli/command/user_keys/hello/windows_hello.py
index dac23c6..b1d9e22 100644
--- a/cryptnox_cli/command/user_keys/hello/windows_hello.py
+++ b/cryptnox_cli/command/user_keys/hello/windows_hello.py
@@ -95,6 +95,7 @@ async def _get_user_credentials(account_id: str) -> KeyCredential:
         return key_result.credential
 
     _error_handle(key_result.status)
+    return None
 
 
 async def _public_key(name: str) -> bytearray:
diff --git a/cryptnox_cli/command/user_keys/piv/piv_card.py b/cryptnox_cli/command/user_keys/piv/piv_card.py
index 0206438..596d6a0 100644
--- a/cryptnox_cli/command/user_keys/piv/piv_card.py
+++ b/cryptnox_cli/command/user_keys/piv/piv_card.py
@@ -220,6 +220,7 @@ def is_locked(self, pin_bank: int) -> bool:
         try:
             self.verify_pin(pin_bank, "")
         except PinException:
+            # Empty PIN rejected as expected; card is not locked
             pass
         except PIVCardException as error:
             if error.sw_code == 0x6983:
diff --git a/cryptnox_cli/interactive_cli.py b/cryptnox_cli/interactive_cli.py
index 2803263..fdfdabe 100644
--- a/cryptnox_cli/interactive_cli.py
+++ b/cryptnox_cli/interactive_cli.py
@@ -219,6 +219,7 @@ def run(self) -> int:
             self._cards.refresh(self.port and client is not None)
             self._card_info = list(self._cards.values())[0].info
         except IndexError:
+            # No cards found yet; leave _card_info unset and continue
             pass
 
         self._cards.print_card_list(show_warnings=True, print_with_one_card=True)
@@ -294,6 +295,7 @@ def _process_command(self):
                 if execute[0] not in ["use", "exit", "back"]:
                     execute[0:0] = self.subcommand
             except LookupError:
+                # Empty command; nothing to prepend, ignore
                 pass
         else:
             self._prepare_parser()
@@ -312,6 +314,7 @@ def _process_command(self):
                 try:
                     self.parser.parse_args(execute)
                 except SystemExit:
+                    # argparse exits on help/error; keep the interactive loop alive
                     pass
                 UsageParser.throw_error = True
         else:
@@ -399,6 +402,7 @@ def _run_command(self, args: argparse.Namespace, to_always_run: List = None) ->
         try:
             self._card_info = self._cards[command.serial_number].info
         except KeyError:
+            # Card no longer present; keep previous _card_info
             pass
         except (cryptnox_sdk_py.exceptions.CryptnoxException, ExitException, TimeoutException) as error:
             print(error)
diff --git a/cryptnox_cli/lib/cryptos/deterministic.py b/cryptnox_cli/lib/cryptos/deterministic.py
index 8a23c84..7045d69 100644
--- a/cryptnox_cli/lib/cryptos/deterministic.py
+++ b/cryptnox_cli/lib/cryptos/deterministic.py
@@ -224,6 +224,8 @@ def bip32_descend(*args, prefixes=DEFAULT):
         path = parse_bip32_path(args[1])
     elif len(args):
         key, path = args[0], list(map(int, args[1:]))
+    else:
+        raise TypeError("bip32_descend() requires at least one positional argument")
     for p in path:
         key = bip32_ckd(key, p, prefixes)
     return bip32_extract_key(key, prefixes)
diff --git a/cryptnox_cli/lib/cryptos/keystore.py b/cryptnox_cli/lib/cryptos/keystore.py
index abdd82e..781aada 100644
--- a/cryptnox_cli/lib/cryptos/keystore.py
+++ b/cryptnox_cli/lib/cryptos/keystore.py
@@ -166,6 +166,7 @@ def get_pubkey_derivation(self, x_pubkey):
             addr = self.coin.p2sh_scriptaddr(x_pubkey[2:])
             if addr in self.addresses:
                 return self.addresses[addr].get('pubkey')
+        return None
 
     def update_password(self, old_password, new_password):
         self.check_password(old_password)
@@ -238,7 +239,7 @@ def derive_pubkey(self, for_change, n):
         return self.get_pubkey_from_xpub(xpub, (n,), self.bip39_prefixes)
 
     @classmethod
-    def get_pubkey_from_xpub(self, xpub, sequence, bip39_prefixes):
+    def get_pubkey_from_xpub(cls, xpub, sequence, bip39_prefixes):
         return bip32_derive_key(xpub, sequence, bip39_prefixes)
 
     """needed?
@@ -352,7 +353,7 @@ class Hardware_KeyStore(KeyStore, Xpub):
     max_change_outputs = 1
 
     def __init__(self, d, coin):
-        Xpub.__init__(self, coin)
+        Xpub.__init__(self)
         KeyStore.__init__(self, coin)
         # Errors and other user interaction is done through the wallet's
         # handler.  The handler is per-window and preserved across
@@ -483,7 +484,7 @@ def xpubkey_to_address(x_pubkey, coin):
         pubkey = x_pubkey
     elif x_pubkey[0:2] == 'ff':
         xpub, s = BIP32_KeyStore.parse_xpubkey(x_pubkey)
-        pubkey = BIP32_KeyStore.get_pubkey_from_xpub(xpub, s)
+        pubkey = BIP32_KeyStore.get_pubkey_from_xpub(xpub, s, coin.bip39_prefixes)
     else:
         raise BaseException("Cannot parse pubkey")
     address = coin.pubtoaddr(pubkey)
@@ -516,11 +517,12 @@ def get_private_keys(text):
     parts = list(filter(bool, parts))
     if bool(parts) and all(bitcoin.is_private_key(x) for x in parts):
         return parts
+    return None
 
 def is_private_key_list(text):
     return bool(get_private_keys(text))
 
-is_mpk = lambda x: is_xpub(x)
+is_mpk = is_xpub
 is_private = lambda x: is_seed(x) or is_xprv(x) or is_private_key_list(x)
 is_master_key = lambda x: is_xprv(x) or is_xpub(x)
 is_private_key = lambda x: is_xprv(x) or is_private_key_list(x)
@@ -568,7 +570,7 @@ def from_master_key(text, coin):
     if is_xprv(text, prefixes):
         k = from_xprv(text, coin)
     elif is_xpub(text, prefixes):
-        k = from_xpub(text, coin)
+        k = from_xpub(text, coin, 'p2pkh')
     else:
         raise BaseException('Invalid key')
     return k
diff --git a/cryptnox_cli/lib/cryptos/main.py b/cryptnox_cli/lib/cryptos/main.py
index 8e9a584..d82da9f 100644
--- a/cryptnox_cli/lib/cryptos/main.py
+++ b/cryptnox_cli/lib/cryptos/main.py
@@ -147,7 +147,7 @@ def jacobian_multiply(a, n):
         return jacobian_multiply(a, n % N)
     if (n % 2) == 0:
         return jacobian_double(jacobian_multiply(a, n // 2))
-    if (n % 2) == 1:
+    else:
         return jacobian_add(jacobian_double(jacobian_multiply(a, n // 2)), a)
 
 
@@ -333,6 +333,7 @@ def compress(pubkey):
         return encode_pubkey(decode_pubkey(pubkey, f), 'bin_compressed')
     elif f == 'hex' or f == 'decimal':
         return encode_pubkey(decode_pubkey(pubkey, f), 'hex_compressed')
+    return None
 
 
 def decompress(pubkey):
@@ -343,6 +344,7 @@ def decompress(pubkey):
         return encode_pubkey(decode_pubkey(pubkey, f), 'bin')
     elif f == 'hex_compressed' or f == 'decimal':
         return encode_pubkey(decode_pubkey(pubkey, f), 'hex')
+    return None
 
 
 def privkey_to_pubkey(privkey):
@@ -398,7 +400,9 @@ def bin_hash160(string):
     digest = ''
     try:
         digest = hashlib.new('ripemd160', intermed).digest()
-    except:
+    except Exception:
+        # 'ripemd160' may be unavailable (e.g. OpenSSL 3 legacy provider off);
+        # fall back to the bundled pure-Python implementation.
         digest = RIPEMD160(intermed).digest()
     return digest
 
@@ -423,7 +427,9 @@ def sha256(string):
 def bin_ripemd160(string):
     try:
         digest = hashlib.new('ripemd160', string).digest()
-    except:
+    except Exception:
+        # 'ripemd160' may be unavailable (e.g. OpenSSL 3 legacy provider off);
+        # fall back to the bundled pure-Python implementation.
         digest = RIPEMD160(string).digest()
     return digest
 
@@ -541,7 +547,7 @@ def is_privkey(priv):
     try:
         get_privkey_format(priv)
         return True
-    except:
+    except Exception:
         return False
 
 
@@ -549,7 +555,7 @@ def is_pubkey(pubkey):
     try:
         get_pubkey_format(pubkey)
         return True
-    except:
+    except Exception:
         return False
 
 
@@ -677,8 +683,9 @@ def subtract(p1, p2):
 
 
 def magicbyte_to_prefix(magicbyte):
+    # Always return a 2-tuple of the low/high address prefix characters.
+    # Callers only test membership over these, so a repeated character when
+    # first == last is harmless and keeps the return shape consistent.
     first = bin_to_b58check(hash160Low, magicbyte=magicbyte)[0]
     last = bin_to_b58check(hash160High, magicbyte=magicbyte)[0]
-    if first == last:
-        return (first,)
     return (first, last)
diff --git a/cryptnox_cli/lib/cryptos/mnemonic.py b/cryptnox_cli/lib/cryptos/mnemonic.py
index e773055..acf784b 100644
--- a/cryptnox_cli/lib/cryptos/mnemonic.py
+++ b/cryptnox_cli/lib/cryptos/mnemonic.py
@@ -16,8 +16,8 @@
 from .specials import *
 from .wallet_utils import is_new_seed
 
-wordlist_english = [word.strip() for word in
-                    list(open(os.path.join(os.path.dirname(os.path.realpath(__file__)), 'english.txt'), 'r'))]
+with open(os.path.join(os.path.dirname(os.path.realpath(__file__)), 'english.txt'), 'r') as _wordlist_file:
+    wordlist_english = [word.strip() for word in _wordlist_file]
 
 ELECTRUM_VERSION = '3.0.5'  # version of the client package
 PROTOCOL_VERSION = '1.1'  # protocol version requested
@@ -226,6 +226,7 @@ def seed_prefix(seed_type):
         return SEED_PREFIX_SW
     elif seed_type == '2fa':
         return SEED_PREFIX_2FA
+    return None
 
 
 def seed_type(x):
diff --git a/cryptnox_cli/lib/cryptos/ripemd.py b/cryptnox_cli/lib/cryptos/ripemd.py
index 86c0b6b..8415a3c 100644
--- a/cryptnox_cli/lib/cryptos/ripemd.py
+++ b/cryptnox_cli/lib/cryptos/ripemd.py
@@ -52,7 +52,8 @@
 
 try:
     range = xrange
-except:
+except NameError:
+    # Python 3: xrange does not exist; the built-in range is already lazy.
     pass
 
 class RIPEMD160:
@@ -164,7 +165,6 @@ def R(a, b, c, d, e, Fj, Kj, sj, rj, X):
 import struct
 
 def RMD160Transform(state, block): #uint32 state[5], uchar block[64]
-    x = [0]*16
     if sys.byteorder == 'little':
         if is_python2:
             x = struct.unpack('<16L', ''.join([chr(x) for x in block[0:64]]))
@@ -369,8 +369,6 @@ def RMD160Transform(state, block): #uint32 state[5], uchar block[64]
     state[4] = (state[0] + bb + c) % 0x100000000;
     state[0] = t % 0x100000000;
 
-    pass
-
 
 def RMD160Update(ctx, inp, inplen):
     if type(inp) == str:
diff --git a/cryptnox_cli/lib/cryptos/stealth.py b/cryptnox_cli/lib/cryptos/stealth.py
index ca769d7..6a6c0c2 100644
--- a/cryptnox_cli/lib/cryptos/stealth.py
+++ b/cryptnox_cli/lib/cryptos/stealth.py
@@ -83,6 +83,9 @@ def mk_stealth_tx_outputs(stealth_addr, value, ephem_privkey, nonce, network='bt
             raise Exception('Invalid testnet stealth address: ' + stealth_addr)
         magic_byte_addr = 111
 
+    else:
+        raise Exception('Unknown network: ' + str(network))
+
     ephem_pubkey = main.privkey_to_pubkey(ephem_privkey)
     output0 = {'script': mk_stealth_metadata_script(ephem_pubkey, nonce),
                'value': 0}
diff --git a/cryptnox_cli/lib/cryptos/transaction.py b/cryptnox_cli/lib/cryptos/transaction.py
index 35da75d..e442ad2 100644
--- a/cryptnox_cli/lib/cryptos/transaction.py
+++ b/cryptnox_cli/lib/cryptos/transaction.py
@@ -78,7 +78,7 @@ def deserialize(tx):
     if isinstance(tx, str) and re.match('^[0-9a-fA-F]*$', tx):
         # tx = bytes(bytearray.fromhex(tx))
         return json_changebase(deserialize(binascii.unhexlify(tx)),
-                               lambda x: safe_hexlify(x))
+                               safe_hexlify)
     # http://stackoverflow.com/questions/4851463/python-closure-write-to-variable-in-parent-scope
     # Python's scoping rules are demented, requiring me to make pos an object
     # so that it is call-by-reference
@@ -148,7 +148,7 @@ def serialize(txobj, include_witness=True):
         txobj = bytes_to_hex_string(txobj)
     o = []
     if json_is_base(txobj, 16):
-        json_changedbase = json_changebase(txobj, lambda x: binascii.unhexlify(x))
+        json_changedbase = json_changebase(txobj, binascii.unhexlify)
         hexlified = safe_hexlify(serialize(json_changedbase, include_witness=include_witness))
         return hexlified
     o.append(encode_4_bytes(txobj["version"]))
@@ -178,7 +178,7 @@ def uahf_digest(txobj, i):
     o = []
 
     if json_is_base(txobj, 16):
-        txobj = json_changebase(txobj, lambda x: binascii.unhexlify(x))
+        txobj = json_changebase(txobj, binascii.unhexlify)
     o.append(encode(txobj["version"], 256, 4)[::-1])
 
     serialized_ins = []
@@ -373,7 +373,7 @@ def p2wpkh_nested_script(pubkey):
 def deserialize_script(script):
     if isinstance(script, str) and re.match('^[0-9a-fA-F]*$', script):
        return json_changebase(deserialize_script(binascii.unhexlify(script)),
-                              lambda x: safe_hexlify(x))
+                              safe_hexlify)
     out, pos = [], 0
     while pos < len(script):
         code = from_byte_to_int(script[pos])
@@ -420,13 +420,13 @@ def serialize_script_unit(unit):
     def serialize_script(script):
         if json_is_base(script, 16):
             return binascii.hexlify(serialize_script(json_changebase(script,
-                                    lambda x: binascii.unhexlify(x))))
+                                    binascii.unhexlify)))
         return ''.join(map(serialize_script_unit, script))
 else:
     def serialize_script(script):
         if json_is_base(script, 16):
             return safe_hexlify(serialize_script(json_changebase(script,
-                                    lambda x: binascii.unhexlify(x))))
+                                    binascii.unhexlify)))
         result = bytes()
         for b in map(serialize_script_unit, script):
             result += b if isinstance(b, bytes) else bytes(b, 'utf-8')
@@ -507,6 +507,4 @@ def select(unspent, value):
         i += 1
     if tv < value:
         raise Exception("Not enough funds")
-    unspents = low[:i]
-    actual_value = sum(unspent['value'] for unspent in unspents)
     return low[:i]
diff --git a/cryptnox_cli/lib/cryptos/wallet.py b/cryptnox_cli/lib/cryptos/wallet.py
index 3a8e104..a509642 100644
--- a/cryptnox_cli/lib/cryptos/wallet.py
+++ b/cryptnox_cli/lib/cryptos/wallet.py
@@ -28,7 +28,7 @@ def __init__(self, keystore, num_addresses=0, last_receiving_index=0, last_chang
 
     def privkey(self, address, formt="wif_compressed", password=None):
         if self.is_watching_only:
-            return
+            return None
         try:
             addr_derivation = self.addresses[address]
         except KeyError:
@@ -39,7 +39,7 @@ def privkey(self, address, formt="wif_compressed", password=None):
 
     def export_privkeys(self, password=None):
         if self.is_watching_only:
-            return
+            return None
         return {
             'receiving': {addr: self.privkey(addr, password=password) for addr in self.receiving_addresses},
             'change': {addr: self.privkey(addr, password=password) for addr in self.change_addresses}
@@ -58,6 +58,7 @@ def pubtoaddr(self, pubkey):
             return self.coin.pubtosegwit(pubkey)
         elif self.keystore.xtype == "p2wpkh-p2sh":
             return self.coin.pubtop2w(pubkey)
+        return None
 
     def receiving_address(self, index):
         pubkey = self.pubkey_receiving(index)
@@ -149,4 +150,4 @@ def details(self, password=None):
             'xchange': (),
             'receiving': [self.account(a, password=password) for a in self.receiving_addresses],
             'change': [self.account(a, password=password) for a in self.change_addresses]
-        }
\ No newline at end of file
+        }
diff --git a/cryptnox_cli/lib/cryptos/wallet_utils.py b/cryptnox_cli/lib/cryptos/wallet_utils.py
index 4e2579e..f046919 100644
--- a/cryptnox_cli/lib/cryptos/wallet_utils.py
+++ b/cryptnox_cli/lib/cryptos/wallet_utils.py
@@ -78,7 +78,7 @@ def __str__(self):
 
 try:
     from Cryptodome.Cipher import AES
-except:
+except ImportError:
     AES = None
 
 
diff --git a/cryptnox_cli/wallet/btc.py b/cryptnox_cli/wallet/btc.py
index 3a060df..11e57ee 100644
--- a/cryptnox_cli/wallet/btc.py
+++ b/cryptnox_cli/wallet/btc.py
@@ -6,7 +6,6 @@
 import json
 import re
 import urllib.parse
-import urllib.request
 import requests
 from enum import Enum
 from typing import Union, List, Dict
@@ -85,13 +84,15 @@ def get_data(self, endpoint: str, params: Dict = None, data: bytes = None) \
             if not parsed.hostname or 'blockcypher.com' not in parsed.hostname:
                 raise ValueError("Invalid URL: must be blockcypher.com domain")
 
-            req = urllib.request.Request(
-                full_url,
-                headers={'User-Agent': 'Mozilla/5.0'},
-                data=data
-            )
-            self.web_rsc = urllib.request.urlopen(req, timeout=30)
-            self.js_res = json.load(self.web_rsc)
+            # Use 'requests' (validated allow-listed https URL) instead of urllib,
+            # which would also honour file:// and other local schemes.
+            headers = {'User-Agent': 'Mozilla/5.0'}
+            if data is None:
+                response = requests.get(full_url, headers=headers, timeout=30)
+            else:
+                response = requests.post(full_url, headers=headers, data=data, timeout=30)
+            response.raise_for_status()
+            self.js_res = response.json()
             self.web_rsc = None
         except Exception as ex:
             print(ex)
@@ -237,19 +238,20 @@ def get_data(self, endpoint: str, params: Dict = None, data: bytes = None) \
             headers = {'User-Agent': 'Mozilla/5.0'}
             if self.api_key:
                 headers['x-token'] = self.api_key
-            req = urllib.request.Request(
-                full_url,
-                headers=headers,
-                data=data
-            )
-            self.web_rsc = urllib.request.urlopen(req, timeout=30)
-            b_rep = self.web_rsc.read()
+            # Use 'requests' (validated allow-listed https URL) instead of urllib,
+            # which would also honour file:// and other local schemes.
+            if data is None:
+                response = requests.get(full_url, headers=headers, timeout=30)
+            else:
+                response = requests.post(full_url, headers=headers, data=data, timeout=30)
+            response.raise_for_status()
+            b_rep = response.content
             if len(b_rep) == 64 and b_rep[0] != ord('{'):
                 b_rep = b'{"txid":"' + b_rep + b'"}'
             self.js_res = json.loads(b_rep)
-        except urllib.error.HTTPError as error:
-            raise IOError(f"Error while processing request:\n{error.code} - "
-                          f"{error.read().decode('utf8')}") from error
+        except requests.exceptions.HTTPError as error:
+            raise IOError(f"Error while processing request:\n{error.response.status_code} - "
+                          f"{error.response.text}") from error
         except Exception as error:
             raise IOError(f"Error while processing request:\n{self.url}{endpoint}?params_enc\n"
                           f"{error}") from error
diff --git a/cryptnox_cli/wallet/eth/api.py b/cryptnox_cli/wallet/eth/api.py
index 631d3ca..6f85483 100644
--- a/cryptnox_cli/wallet/eth/api.py
+++ b/cryptnox_cli/wallet/eth/api.py
@@ -80,6 +80,7 @@ def transaction_hash(self, transaction: Dict[str, Any], vrs: bool = False):
             del transaction["maxFeePerGas"]
             del transaction["maxPriorityFeePerGas"]
         except KeyError:
+            # EIP-1559 fee fields absent (legacy transaction); nothing to remove
             pass
         unsigned_transaction = serializable_unsigned_transaction_from_dict(transaction)
         encoded_transaction = encode_transaction(unsigned_transaction, (self._chain_id, 0, 0))
diff --git a/dev-requirements.txt b/dev-requirements.txt
index c0d3069..ec683d3 100644
Binary files a/dev-requirements.txt and b/dev-requirements.txt differ
diff --git a/requirements.txt b/requirements.txt
index 0f54754..815dd6d 100644
Binary files a/requirements.txt and b/requirements.txt differ