diff --git a/bijoe/visualization/signature.py b/bijoe/visualization/signature.py
index 7b3245b..b542b76 100644
--- a/bijoe/visualization/signature.py
+++ b/bijoe/visualization/signature.py
@@ -22,10 +22,11 @@ import urllib
 import random
 import logging
 
+from django.utils import six
 from django.utils.encoding import force_bytes, smart_bytes
+from django.utils.http import quote, urlencode
 from django.utils.six.moves.urllib import parse as urlparse
 
-
 '''Simple signature scheme for query strings'''
 # from http://repos.entrouvert.org/portail-citoyen.git/tree/portail_citoyen/apps/data_source_plugin/signature.py
 
@@ -45,12 +46,12 @@ def sign_query(query, key, algo='sha256', timestamp=None, nonce=None):
     new_query = query
     if new_query:
         new_query += '&'
-    new_query += urllib.urlencode((
+    new_query += urlencode((
         ('algo', algo),
         ('timestamp', timestamp),
         ('nonce', nonce)))
     signature = base64.b64encode(sign_string(new_query, key, algo=algo))
-    new_query += '&signature=' + urllib.quote(signature)
+    new_query += '&signature=' + quote(signature)
     return new_query
 
 
@@ -88,7 +89,7 @@ def check_query2(query, key, known_nonce, timedelta):
     except Exception as e:
         return False, 'could not decode base64 signature (%s)' % e
 
-    if algo not in hashlib.algorithms:
+    if algo not in hashlib.algorithms_guaranteed:
         return False, 'hash algorithm %s is not supported' % algo
 
     try:
@@ -111,6 +112,10 @@ def check_string(s, signature, key, algo='sha256'):
     if len(signature2) != len(signature):
         return False
     res = 0
-    for a, b in zip(signature, signature2):
-        res |= ord(a) ^ ord(b)
+    if six.PY3:
+        for a, b in zip(signature, signature2):
+            res |= a ^ b
+    else:
+        for a, b in zip(signature, signature2):
+            res |= ord(a) ^ ord(b)
     return res == 0