Verify the signature on user cloud policy downloads.

net/tools/testserver/device_management.py

Index: net/tools/testserver/device_management.py
diff --git a/net/tools/testserver/device_management.py b/net/tools/testserver/device_management.py
index bbfb3c5ff08871773c7a0b29c3a130201a6a2bd4..6ad06225ea8dd61edad42f495bd90d9ad88a6e73 100644
--- a/net/tools/testserver/device_management.py
+++ b/net/tools/testserver/device_management.py
@@ -45,7 +45,8 @@ Example:
   },
   "managed_users" : [
     "secret123456"
-  ]
+  ],
+  "current_key_index": 0
 }
 
 """
@@ -455,18 +456,17 @@ class RequestHandler(object):
         settings = dp.ChromeDeviceSettingsProto()
         self.GatherDevicePolicySettings(settings, policy.get(policy_key, {}))
 
-    # Figure out the key we want to use. If multiple keys are configured, the
-    # server will rotate through them in a round-robin fashion.
+    # Sign with 'current_key_index', defaulting to key 0.
     signing_key = None
     req_key = None
-    key_version = 1
+    current_key_index = policy.get('current_key_index', 0)
     nkeys = len(self._server.keys)
-    if msg.signature_type == dm.PolicyFetchRequest.SHA1_RSA and nkeys > 0:
+    if (msg.signature_type == dm.PolicyFetchRequest.SHA1_RSA and
+        current_key_index in range(nkeys)):
+      signing_key = self._server.keys[current_key_index]
       if msg.public_key_version in range(1, nkeys + 1):
         # requested key exists, use for signing and rotate.
         req_key = self._server.keys[msg.public_key_version - 1]['private_key']
-        key_version = (msg.public_key_version % nkeys) + 1
-      signing_key = self._server.keys[key_version - 1]
 
     # Fill the policy data protobuf.
     policy_data = dm.PolicyData()
@@ -480,7 +480,7 @@ class RequestHandler(object):
     policy_data.settings_entity_id = msg.settings_entity_id
 
     if signing_key:
-      policy_data.public_key_version = key_version
+      policy_data.public_key_version = current_key_index + 1
     if msg.policy_type == 'google/chromeos/publicaccount':
       policy_data.username = msg.settings_entity_id
     else:
@@ -498,7 +498,7 @@ class RequestHandler(object):
     if signing_key:
       fetch_response.policy_data_signature = (
           signing_key['private_key'].hashAndSign(signed_data).tostring())
-      if msg.public_key_version != key_version:
+      if msg.public_key_version != current_key_index + 1:
         fetch_response.new_public_key = signing_key['public_key']
         if req_key:
           fetch_response.new_public_key_signature = (
@@ -549,35 +549,23 @@ class RequestHandler(object):
 class TestServer(object):
   """Handles requests and keeps global service state."""
 
-  def __init__(self, policy_path, private_key_paths):
+  def __init__(self, policy_path):
     """Initializes the server.
 
     Args:
       policy_path: Names the file to read JSON-formatted policy from.
-      private_key_paths: List of paths to read private keys from.
     """
     self._registered_tokens = {}
     self.policy_path = policy_path
 
+    # Generate 2 private keys.
     self.keys = []
-    if private_key_paths:
-      # Load specified keys from the filesystem.
-      for key_path in private_key_paths:
-        try:
-          key = tlslite.api.parsePEMKey(open(key_path).read(), private=True)
-        except IOError:
-          print 'Failed to load private key from %s' % key_path
-          continue
-
-        assert key is not None
-        self.keys.append({ 'private_key' : key })
-    else:
-      # Generate a key if none were specified.
-      key = tlslite.api.generateRSAKey(1024)
+    for i in range(2):
+      key = tlslite.api.generateRSAKey(512)

[Mattias Nissler (ping if slow), 2013/02/07 14:12:07]

I'd hate to loose the ability to use keys passed on the command line - that
feature has been very handy when I needed to generate valid policy blobs for
seeding a client that couldn't register when working on the public accounts
stuff.

[Joao da Silva, 2013/02/07 16:32:00]

Reverted.

       assert key is not None
       self.keys.append({ 'private_key' : key })
 
-    # Derive the public keys from the loaded private keys.
+    # Derive the public keys from the generated private keys.
     for entry in self.keys:
       key = entry['private_key']