digitalbitbox: make constant strings

electrum/plugins/digitalbitbox/digitalbitbox.py

@@ -53,6 +53,9 @@ def derive_keys(x):
 
 MIN_MAJOR_VERSION = 5
 
+ENCRYPTION_PRIVKEY_KEY = 'encryptionprivkey'
+CHANNEL_ID_KEY = 'comserverchannelid'
+
 class DigitalBitbox_Client():
 
     def __init__(self, plugin, hidDevice):
@@ -280,7 +283,7 @@ class DigitalBitbox_Client():
         except (FileNotFoundError, jsonDecodeError):
             return
 
-        if 'encryptionprivkey' not in dbb_config or 'comserverchannelid' not in dbb_config:
+        if ENCRYPTION_PRIVKEY_KEY not in dbb_config or CHANNEL_ID_KEY not in dbb_config:
             return
 
         choices = [
@@ -294,12 +297,12 @@ class DigitalBitbox_Client():
 
         if reply == 0:
             if self.plugin.is_mobile_paired():
-                del self.plugin.digitalbitbox_config['encryptionprivkey']
-                del self.plugin.digitalbitbox_config['comserverchannelid']
+                del self.plugin.digitalbitbox_config[ENCRYPTION_PRIVKEY_KEY]
+                del self.plugin.digitalbitbox_config[CHANNEL_ID_KEY]
         elif reply == 1:
             # import pairing from dbb app
-            self.plugin.digitalbitbox_config['encryptionprivkey'] = dbb_config['encryptionprivkey']
-            self.plugin.digitalbitbox_config['comserverchannelid'] = dbb_config['comserverchannelid']
+            self.plugin.digitalbitbox_config[ENCRYPTION_PRIVKEY_KEY] = dbb_config[ENCRYPTION_PRIVKEY_KEY]
+            self.plugin.digitalbitbox_config[CHANNEL_ID_KEY] = dbb_config[CHANNEL_ID_KEY]
         self.plugin.config.set_key('digitalbitbox', self.plugin.digitalbitbox_config)
 
     def dbb_generate_wallet(self):
@@ -729,15 +732,15 @@ class DigitalBitboxPlugin(HW_PluginBase):
 
 
     def is_mobile_paired(self):
-        return 'encryptionprivkey' in self.digitalbitbox_config
+        return ENCRYPTION_PRIVKEY_KEY in self.digitalbitbox_config
 
 
     def comserver_post_notification(self, payload):
         assert self.is_mobile_paired(), "unexpected mobile pairing error"
         url = 'https://digitalbitbox.com/smartverification/index.php'
-        key_s = base64.b64decode(self.digitalbitbox_config['encryptionprivkey'])
+        key_s = base64.b64decode(self.digitalbitbox_config[ENCRYPTION_PRIVKEY_KEY])
         args = 'c=data&s=0&dt=0&uuid=%s&pl=%s' % (
-            self.digitalbitbox_config['comserverchannelid'],
+            self.digitalbitbox_config[CHANNEL_ID_KEY],
             EncodeAES_base64(key_s, json.dumps(payload).encode('ascii')).decode('ascii'),
         )
         try: