check key-confirmation messages, if present

src/wormhole/blocking/transcribe.py

@@ -214,6 +214,7 @@ class Wormhole:
         self.verifier = None
         self._sent_data = set() # phases
         self._got_data = set()
+        self._got_confirmation = False
         self._closed = False
 
     def __enter__(self):
@@ -355,10 +356,20 @@ class Wormhole:
         if self._channel is None: raise UsageError
         self._got_data.add(phase)
         self._get_key()
-        data_key = self.derive_key(u"wormhole:phase:%s" % phase)
-        inbound_encrypted = self._channel.get(phase)
+        phases = []
+        if not self._got_confirmation:
+            phases.append(u"_confirm")
+        phases.append(phase)
+        (got_phase, body) = self._channel.get_first_of(phases)
+        if got_phase == u"_confirm":
+            if body != self.derive_key(u"wormhole:confirmation"):
+                raise WrongPasswordError
+            self._got_confirmation = True
+            (got_phase, body) = self._channel.get_first_of([phase])
+        assert got_phase == phase
         try:
-            inbound_data = self._decrypt_data(data_key, inbound_encrypted)
+            data_key = self.derive_key(u"wormhole:phase:%s" % phase)
+            inbound_data = self._decrypt_data(data_key, body)
             return inbound_data
         except CryptoError:
             raise WrongPasswordError

src/wormhole/test/test_blocking.py

@@ -3,7 +3,8 @@ import json
 from twisted.trial import unittest
 from twisted.internet.defer import gatherResults, succeed
 from twisted.internet.threads import deferToThread
-from ..blocking.transcribe import Wormhole, UsageError, ChannelManager
+from ..blocking.transcribe import (Wormhole, UsageError, ChannelManager,
+                                   WrongPasswordError)
 from ..blocking.eventsource import EventSourceFollower
 from .common import ServerBase
 
@@ -246,6 +247,35 @@ class Blocking(ServerBase, unittest.TestCase):
         d.addCallback(_got_2)
         return d
 
+    def test_wrong_password(self):
+        w1 = Wormhole(APPID, self.relayurl)
+        w2 = Wormhole(APPID, self.relayurl)
+
+        # make sure we can detect WrongPasswordError even if one side only
+        # does get_data() and not send_data(), like "wormhole receive" does
+        d = deferToThread(w1.get_code)
+        d.addCallback(lambda code: w2.set_code(code+"not"))
+
+        # w2 can't throw WrongPasswordError until it sees a CONFIRM message,
+        # and w1 won't send CONFIRM until it sees a PAKE message, which w2
+        # won't send until we call get_data. So we need both sides to be
+        # running at the same time for this test.
+        def _w1_sends():
+            w1.send_data(b"data1")
+        def _w2_gets():
+            self.assertRaises(WrongPasswordError, w2.get_data)
+        d.addCallback(lambda _: self.doBoth([_w1_sends], [_w2_gets]))
+
+        # and now w1 should have enough information to throw too
+        d.addCallback(lambda _: deferToThread(self.assertRaises,
+                                              WrongPasswordError, w1.get_data))
+        def _done(_):
+            # both sides are closed automatically upon error, but it's still
+            # legal to call .close(), and should be idempotent
+            return self.doBoth([w1.close], [w2.close])
+        d.addCallback(_done)
+        return d
+
     def test_verifier(self):
         w1 = Wormhole(APPID, self.relayurl)
         w2 = Wormhole(APPID, self.relayurl)

src/wormhole/test/test_twisted.py

@@ -2,7 +2,8 @@ from __future__ import print_function
 import sys, json
 from twisted.trial import unittest
 from twisted.internet.defer import gatherResults, succeed
-from ..twisted.transcribe import Wormhole, UsageError, ChannelManager
+from ..twisted.transcribe import (Wormhole, UsageError, ChannelManager,
+                                  WrongPasswordError)
 from ..twisted.eventsource_twisted import EventSourceParser
 from .common import ServerBase
 
@@ -229,6 +230,32 @@ class Basic(ServerBase, unittest.TestCase):
         d.addCallback(_got_2)
         return d
 
+    def test_wrong_password(self):
+        w1 = Wormhole(APPID, self.relayurl)
+        w2 = Wormhole(APPID, self.relayurl)
+        d = w1.get_code()
+        d.addCallback(lambda code: w2.set_code(code+"not"))
+
+        # w2 can't throw WrongPasswordError until it sees a CONFIRM message,
+        # and w1 won't send CONFIRM until it sees a PAKE message, which w2
+        # won't send until we call get_data. So we need both sides to be
+        # running at the same time for this test.
+        def _w1_sends():
+            return w1.send_data(b"data1")
+        def _w2_gets():
+            return self.assertFailure(w2.get_data(), WrongPasswordError)
+        d.addCallback(lambda _: self.doBoth(_w1_sends(), _w2_gets()))
+
+        # and now w1 should have enough information to throw too
+        d.addCallback(lambda _: self.assertFailure(w1.get_data(),
+                                                   WrongPasswordError))
+        def _done(_):
+            # both sides are closed automatically upon error, but it's still
+            # legal to call .close(), and should be idempotent
+            return self.doBoth(w1.close(), w2.close())
+        d.addCallback(_done)
+        return d
+
     def test_verifier(self):
         w1 = Wormhole(APPID, self.relayurl)
         w2 = Wormhole(APPID, self.relayurl)

src/wormhole/twisted/transcribe.py

@@ -206,6 +206,7 @@ class Wormhole:
         self._started_get_code = False
         self._sent_data = set() # phases
         self._got_data = set()
+        self._got_confirmation = False
 
     def _set_side(self, side):
         self._side = side
@@ -375,16 +376,30 @@ class Wormhole:
         self._got_data.add(phase)
         d = self._get_key()
         def _get(key):
-            data_key = self.derive_key(u"wormhole:phase:%s" % phase)
-            d1 = self._channel.get(phase)
-            def _decrypt(inbound_encrypted):
+            phases = []
+            if not self._got_confirmation:
+                phases.append(u"_confirm")
+            phases.append(phase)
+            d1 = self._channel.get_first_of(phases)
+            def _maybe_got_confirm(phase_and_body):
+                (got_phase, body) = phase_and_body
+                if got_phase == u"_confirm":
+                    if body != self.derive_key(u"wormhole:confirmation"):
+                        raise WrongPasswordError
+                    self._got_confirmation = True
+                    return self._channel.get_first_of([phase])
+                return phase_and_body
+            d1.addCallback(_maybe_got_confirm)
+            def _got(phase_and_body):
+                (got_phase, body) = phase_and_body
+                assert got_phase == phase
                 try:
-                    inbound_data = self._decrypt_data(data_key,
-                                                      inbound_encrypted)
+                    data_key = self.derive_key(u"wormhole:phase:%s" % phase)
+                    inbound_data = self._decrypt_data(data_key, body)
                     return inbound_data
                 except CryptoError:
                     raise WrongPasswordError
-            d1.addCallback(_decrypt)
+            d1.addCallback(_got)
             return d1
         d.addCallback(_get)
         return d