wallet: refactor: add verify_message method, consolidated from UIs

diff --git a/electrum/commands.py b/electrum/commands.py
index 37686f9..f81628f 100644
--- a/electrum/commands.py
+++ b/electrum/commands.py
@@ -925,12 +925,7 @@ class Commands(Logger):
         arg:str:message:Clear text message. Use quotes if it contains spaces.
         arg:str:signature:The signature, base64-encoded.
         """
-        try:
-            sig = base64.b64decode(signature, validate=True)
-        except binascii.Error:
-            return False
-        message = util.to_bytes(message)
-        return bitcoin.verify_usermessage_with_address(address, sig, message)
+        return Abstract_Wallet.verify_message(address=address, signature=signature, message=message)
 
     def _get_fee_policy(self, fee: str, feerate: str):
         if fee is not None and feerate is not None:
@@ -1236,7 +1231,7 @@ class Commands(Logger):
         try:
             message = to_bytes(message)
         except TypeError:
-            raise UserFacingException(f"message must be a string-like object instead of {repr(message)}")
+            raise UserFacingException(f"message must be a str instead of {repr(message)}")
         public_key = ecc.ECPubkey(bfh(pubkey))
         encrypted = crypto.ecies_encrypt_message(public_key, message)
         return encrypted.decode('utf-8')
@@ -1250,8 +1245,8 @@ class Commands(Logger):
         """
         if not is_hex_str(pubkey):
             raise UserFacingException(f"pubkey must be a hex string instead of {repr(pubkey)}")
-        if not isinstance(encrypted, (str, bytes, bytearray)):
-            raise UserFacingException(f"encrypted must be a string-like object instead of {repr(encrypted)}")
+        if not isinstance(encrypted, str):
+            raise UserFacingException(f"encrypted must be a str instead of {repr(encrypted)}")
         decrypted = wallet.decrypt_message(pubkey, encrypted, password)
         return decrypted.decode('utf-8')
 
diff --git a/electrum/gui/qml/qedaemon.py b/electrum/gui/qml/qedaemon.py
index 679bf5a..2d1983d 100644
--- a/electrum/gui/qml/qedaemon.py
+++ b/electrum/gui/qml/qedaemon.py
@@ -1,4 +1,3 @@
-import base64
 import os
 import threading
 from typing import TYPE_CHECKING
@@ -11,9 +10,8 @@ from electrum.logging import get_logger
 from electrum.util import WalletFileException, standardize_path, InvalidPassword, send_exception_to_crash_reporter
 from electrum.plugin import run_hook
 from electrum.lnchannel import ChannelState
-from electrum.bitcoin import is_address
-from electrum.bitcoin import verify_usermessage_with_address
 from electrum.storage import StorageReadWriteError, WalletStorage
+from electrum.wallet import Abstract_Wallet
 
 from .auth import AuthMixin, auth_protect
 from .qefx import QEFX
@@ -506,16 +504,9 @@ class QEDaemon(AuthMixin, QObject):
     @pyqtSlot(str, str, str, result=bool)
     def verifyMessage(self, address, message, signature):
         address = address.strip()
-        message = message.strip().encode('utf-8')
-        if not is_address(address):
-            return False
-        try:
-            # This can throw on invalid base64
-            sig = base64.b64decode(str(signature.strip()), validate=True)
-            verified = verify_usermessage_with_address(address, sig, message)
-        except Exception as e:
-            verified = False
-        return verified
+        message = message.strip()
+        signature = signature.strip()
+        return Abstract_Wallet.verify_message(address=address, signature=signature, message=message)
 
     @pyqtSlot(str, result=int)
     def passwordStrength(self, password):
diff --git a/electrum/gui/qt/main_window.py b/electrum/gui/qt/main_window.py
index 9363dc2..4811579 100644
--- a/electrum/gui/qt/main_window.py
+++ b/electrum/gui/qt/main_window.py
@@ -2173,16 +2173,12 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         signature_e: ButtonsTextEdit,
     ) -> None:
         address = address_e.text().strip()
-        message = message_e.toPlainText().strip().encode('utf-8')
+        message = message_e.toPlainText().strip()
         if not bitcoin.is_address(address):
             self.show_message(_('Invalid Bitcoin address.'))
             return
-        try:
-            # This can throw on invalid base64
-            sig = base64.b64decode(str(signature_e.toPlainText()), validate=True)
-            verified = bitcoin.verify_usermessage_with_address(address, sig, message)
-        except Exception as e:
-            verified = False
+        verified = self.wallet.verify_message(
+            address=address, signature=str(signature_e.toPlainText()), message=message)
         if verified:
             self.show_message(_("Signature verified"))
         else:
diff --git a/electrum/wallet.py b/electrum/wallet.py
index c5252e1..e29ccd4 100644
--- a/electrum/wallet.py
+++ b/electrum/wallet.py
@@ -41,6 +41,7 @@ import threading
 import enum
 import asyncio
 from dataclasses import dataclass
+import base64
 
 import electrum_ecc as ecc
 from aiorpcx import ignore_after, run_in_thread
@@ -3238,7 +3239,20 @@ class Abstract_Wallet(ABC, Logger, EventListener):
         assert script_type != "address"
         return self.keystore.sign_message(index, message, password, script_type=script_type)
 
-    def decrypt_message(self, pubkey: str, message, password) -> bytes:
+    @classmethod
+    def verify_message(cls, *, address: str, signature: str, message: str) -> bool:
+        if not is_address(address):
+            return False
+        try:
+            sig = base64.b64decode(signature, validate=True)
+        except ValueError:
+            # note: unicode chars in signature would result in ValueError,
+            #       so it is insufficient to catch binascii.Error(ValueError)
+            return False
+        message = util.to_bytes(message)
+        return bitcoin.verify_usermessage_with_address(address, sig, message)
+
+    def decrypt_message(self, pubkey: str, message: str, password) -> bytes:
         addr = self.pubkeys_to_address([pubkey])
         index = self.get_address_index(addr)
         return self.keystore.decrypt_message(index, message, password)