Get rid of default crypto key; use random one at startup

conn.py

@@ -149,6 +149,12 @@ class Connection(metaclass=Singleton):
             logging.info(f"Starting hidden service: %s" % BP['onion_addr'])
             asyncio.create_task(TOR.start_tunnel())
 
+        h = STATUS.hsm
+        if ('summary' in h) and h.summary and not BP.get('priv_over_ux') and not BP.get('summary'):
+            logging.info("Captured CC's summary of the policy")
+            BP['summary'] = h.summary
+            BP.save()
+
         STATUS.reset_pending_auth()
         STATUS.notify_watchers()
 
@@ -195,11 +201,6 @@ class Connection(metaclass=Singleton):
             # won't be required
             STATUS.local_code = None
 
-        if ('summary' in h) and h.summary and not BP.get('priv_over_ux') and not BP.get('summary'):
-            logging.info("Captured CC's summary of the policy")
-            BP['summary'] = h.summary
-            BP.save()
-
         # has it just transitioned into HSM mode?
         if STATUS.connected and STATUS.hsm.active and not b4:
             await self.activated_hsm()

data/README.md

@@ -2,7 +2,8 @@
 # Data Files
 
 - this directory will hold data files for the Bunker
-- they are encrypted with a private key held in the "storage locker" of the Coldcard
-- contents include Tor hidden service private key and settings
+- they are encrypted with a private key held in the "storage locker" of a Coldcard
+- contents include Tor hidden service private key and settings for Bunker
 - filename based on key
-- default key maps to `bp-1850f665aa1e22c0.dat`
+- you may see unused junk accumulate in this directory; those are random keys that
+  never got saved as a policy file for any Coldcard

docs/setup.md

@@ -115,12 +115,9 @@ it reads the storage locker and uses the NaCl private key (32 bytes)
 to select and open the corresponding Bunker settings file. Therefore,
 each Coldcard has it's own settings for the Bunker. 
 
-Before a Coldcard is connected, or before the policy is saved for
-the first time, the settings are held with a fixed key, and end up
-in file: `data/bp-1850f665aa1e22c0.dat` based on that key. At the
-point where you upload a new policy to a Coldcard, a new key is
-picked and added to the policy file. Data on disk at that point is
-re-encrypted and moved over.
+In setup mode, bunker settings are effectively not saved until
+the NaCL secret is saved into the policy of a Coldcard and saved
+there.
 
 
 #### Other Notes

persist.py

@@ -39,10 +39,6 @@ class Settings(metaclass=Singleton):
     # path to data files
     DATA_FILES = './data'
 
-    # used during secret/when we don't have a key yet
-    # - maps to data/bp-1850f665aa1e22c0.dat
-    PLACEHOLDER_KEY = b'ab'*16
-
     # endpoint to use for sending txn; we assume it's Explora protocol (Blockstream.info)
     EXPLORA = 'http://explorerzydxu5ecjrkwceayqybizmpjjznk5izmitf2modhcusuqlid.onion'
 
@@ -111,12 +107,13 @@ class BunkerPersistance(WatchableMixin, dict, metaclass=Singleton):
 
     def __init__(self):
         super(BunkerPersistance, self).__init__()
-        self.key = None
         self.filename = None
-        self.set_defaults()
+        self.reset()
 
     def reset(self):
-        self.open(settings.PLACEHOLDER_KEY)
+        self.clear()
+        self.set_secret(os.urandom(32))
+        self.set_defaults()
 
     def set_defaults(self):
         # defaults here
@@ -135,11 +132,6 @@ class BunkerPersistance(WatchableMixin, dict, metaclass=Singleton):
         bn = 'bp-%s.dat' % sha256(sha256(b'salty' + self.key).digest()).hexdigest()[-16:].lower()
         self.filename =  os.path.join(settings.DATA_FILES, bn)
 
-    @staticmethod
-    def new_secret():
-        # rotate key
-        return os.urandom(32)
-
     def open(self, key):
         # Given a private key (via storage locker) open a Nacl secret box
         # and use that for the data.
@@ -182,8 +174,5 @@ class BunkerPersistance(WatchableMixin, dict, metaclass=Singleton):
         except:
             pass
 
-    def is_default_secret(self):
-        return self.key == settings.PLACEHOLDER_KEY
-
 
 # EOF

policy.py

@@ -129,13 +129,8 @@ def update_sl(proposed):
             xk = None
 
     if not xk:
-        if not BP.key or BP.is_default_secret():
-            # pick a new key
-            logging.info("Making new secret for holding Bunker settings")
-            xk = BP.new_secret()
-        else:
-            # keep using same key
-            xk = BP.key
+        # capture settings key
+        xk = BP.key
 
         assert len(xk) == 32
         proposed['set_sl'] = b64encode(b'Bunk' + xk).decode('ascii')

webapp.py

@@ -480,9 +480,10 @@ async def ws_api_handler(ses, send_json, req, orig_request):     # handle_api
 
         if not BP['tor_enabled']:
             await TOR.stop_tunnel()
-        elif BP.get('onion_pk') and not (STATUS.force_local_mode or STATUS.setup_mode):
-            # connect/reconnect
-            await TOR.start_tunnel()
+        elif BP.get('onion_pk') and not (STATUS.force_local_mode or STATUS.setup_mode) \
+            and TOR.get_current_addr() != BP.get('onion_addr'):
+                # disconnect/reconnect
+                await TOR.start_tunnel()
 
     elif action == 'sign_message':
         # sign a short text message