Don't make signature verification a method of the object being verified

That approach opens a door to someone pickling a totally different class
with a bad verify method, and things of that nature.

client.py

@@ -109,7 +109,7 @@ if __name__ == '__main__':
     # Tick the epoch
     network.thenetwork.nextepoch()
 
-    dirauth.DirAuth.consensus.verify(network.thenetwork.dirauthkeys())
+    dirauth.verify_consensus(dirauth.DirAuth.consensus, network.thenetwork.dirauthkeys())
 
     print('ticked; epoch=', network.thenetwork.getepoch())
 

dirauth.py

@@ -37,9 +37,10 @@ class RelayDescriptor:
         signed = signingkey.sign(serialized.encode("ascii"))
         self.descdict["sig"] = signed.signature
 
-    def verify(self):
-        serialized = self.__str__(False)
-        self.descdict["idkey"].verify(serialized.encode("ascii"), self.descdict["sig"])
+
+def verify_relaydesc(desc):
+    serialized = desc.__str__(False)
+    desc.descdict["idkey"].verify(serialized.encode("ascii"), desc.descdict["sig"])
 
 
 # A consensus is a dict containing:
@@ -81,12 +82,13 @@ class Consensus:
             self.consdict['sigs'].extend([None] * (index+1-len(self.consdict['sigs'])))
         self.consdict['sigs'][index] = signed.signature
 
-    def verify(self, verifkeylist):
-        """Use the given list of verification keys to check the
-        signatures on the consensus."""
-        serialized = self.__str__(False)
-        for i, vk in enumerate(verifkeylist):
-            vk.verify(serialized.encode("ascii"), self.consdict['sigs'][i])
+
+def verify_consensus(consensus, verifkeylist):
+    """Use the given list of verification keys to check the
+    signatures on the consensus."""
+    serialized = consensus.__str__(False)
+    for i, vk in enumerate(verifkeylist):
+        vk.verify(serialized.encode("ascii"), consensus.consdict['sigs'][i])
 
 
 class DirAuthNetMsg(network.NetMsg):

relay.py

@@ -266,7 +266,7 @@ class Relay(network.Server):
         descdict["flags"] = self.flags
         desc = dirauth.RelayDescriptor(descdict)
         desc.sign(self.idkey)
-        desc.verify()
+        dirauth.verify_relaydesc(desc)
 
         if upload:
             descmsg = dirauth.DirAuthUploadDescMsg(desc)
@@ -336,7 +336,7 @@ if __name__ == '__main__':
     # Tick the epoch
     network.thenetwork.nextepoch()
 
-    dirauth.DirAuth.consensus.verify(network.thenetwork.dirauthkeys())
+    dirauth.verify_consensus(dirauth.DirAuth.consensus, network.thenetwork.dirauthkeys())
 
     print('ticked; epoch=', network.thenetwork.getepoch())