diff --git a/acme/messages2.py b/acme/messages2.py
index 419bb0b4e..ac26d2e97 100644
--- a/acme/messages2.py
+++ b/acme/messages2.py
@@ -18,11 +18,9 @@ class Error(jose.JSONObjectWithFields, Exception):
         'badCSR': 'The CSR is unacceptable (e.g., due to a short key)',
     }
 
-    # TODO: Boulder omits 'type' and 'instance', spec requires, boulder#128
     typ = jose.Field('type', omitempty=True)
     title = jose.Field('title', omitempty=True)
     detail = jose.Field('detail')
-    instance = jose.Field('instance', omitempty=True)
 
     @typ.encoder
     def typ(value):  # pylint: disable=missing-docstring,no-self-argument
@@ -227,10 +225,6 @@ class Authorization(ResourceBody):
     challenges = jose.Field('challenges', omitempty=True)
     combinations = jose.Field('combinations', omitempty=True)
 
-    # TODO: acme-spec #92, #98
-    key = Registration._fields['key']
-    contact = Registration._fields['contact']
-
     status = jose.Field('status', omitempty=True, decoder=Status.from_json)
     # TODO: 'expires' is allowed for Authorization Resources in
     # general, but for Key Authorization '[t]he "expires" field MUST
diff --git a/letsencrypt/network2.py b/letsencrypt/network2.py
index b82b05bbe..28cb702a3 100644
--- a/letsencrypt/network2.py
+++ b/letsencrypt/network2.py
@@ -248,6 +248,7 @@ class Network(object):
 
     def _authzr_from_response(self, response, identifier,
                               uri=None, new_cert_uri=None):
+        # pylint: disable=no-self-use
         if new_cert_uri is None:
             try:
                 new_cert_uri = response.links['next']['url']
@@ -258,8 +259,7 @@ class Network(object):
             body=messages2.Authorization.from_json(response.json()),
             uri=response.headers.get('Location', uri),
             new_cert_uri=new_cert_uri)
-        if (authzr.body.key != self.key.public()
-                or authzr.body.identifier != identifier):
+        if authzr.body.identifier != identifier:
             raise errors.UnexpectedUpdate(authzr)
         return authzr
 
diff --git a/letsencrypt/tests/auth_handler_test.py b/letsencrypt/tests/auth_handler_test.py
index f7c7a888f..85bcfe8cf 100644
--- a/letsencrypt/tests/auth_handler_test.py
+++ b/letsencrypt/tests/auth_handler_test.py
@@ -276,8 +276,6 @@ class PollChallengesTest(unittest.TestCase):
                 identifier=authzr.body.identifier,
                 challenges=new_challbs,
                 combinations=authzr.body.combinations,
-                key=authzr.body.key,
-                contact=authzr.body.contact,
                 status=status_,
             ),
         )
diff --git a/letsencrypt/tests/network2_test.py b/letsencrypt/tests/network2_test.py
index d7f50328a..bfe3e89b4 100644
--- a/letsencrypt/tests/network2_test.py
+++ b/letsencrypt/tests/network2_test.py
@@ -72,7 +72,7 @@ class NetworkTest(unittest.TestCase):
         self.authz = messages2.Authorization(
             identifier=messages2.Identifier(
                 typ=messages2.IDENTIFIER_FQDN, value='example.com'),
-            challenges=(challb,), combinations=None, key=KEY.public())
+            challenges=(challb,), combinations=None)
         self.authzr = messages2.AuthorizationResource(
             body=self.authz, uri=authzr_uri,
             new_cert_uri='https://www.letsencrypt-demo.org/acme/new-cert')
@@ -258,11 +258,10 @@ class NetworkTest(unittest.TestCase):
         # TODO: test POST call arguments
 
         # TODO: split here and separate test
-        authz_wrong_key = self.authz.update(key=KEY2.public())
-        self.response.json.return_value = authz_wrong_key.to_json()
-        self.assertRaises(
-            errors.UnexpectedUpdate, self.net.request_challenges,
-            self.identifier, self.regr)
+        self.response.json.return_value = self.authz.update(
+            identifier=self.identifier.update(value='foo')).to_json()
+        self.assertRaises(errors.UnexpectedUpdate, self.net.request_challenges,
+                          self.identifier, self.authzr.uri)
 
     def test_request_challenges_missing_next(self):
         self.response.status_code = httplib.CREATED
@@ -336,6 +335,11 @@ class NetworkTest(unittest.TestCase):
         self.assertEqual((self.authzr, self.response),
                          self.net.poll(self.authzr))
 
+        # TODO: split here and separate test
+        self.response.json.return_value = self.authz.update(
+            identifier=self.identifier.update(value='foo')).to_json()
+        self.assertRaises(errors.UnexpectedUpdate, self.net.poll, self.authzr)
+
     def test_request_issuance(self):
         self.response.content = CERT.as_der()
         self.response.headers['Location'] = self.certr.uri