Increase default PBKDF2 iterations

Increases the default PBKDF2 iterations, since computers have gotten
faster since 2011. In the future, we plan to increment by 10% per
major version.

django/contrib/auth/hashers.py

@@ -231,12 +231,12 @@ class PBKDF2PasswordHasher(BasePasswordHasher):
     """
     Secure password hashing using the PBKDF2 algorithm (recommended)
 
-    Configured to use PBKDF2 + HMAC + SHA256 with 10000 iterations.
+    Configured to use PBKDF2 + HMAC + SHA256 with 12000 iterations.
     The result is a 64 byte binary string.  Iterations may be changed
     safely but you must rename the algorithm if you change SHA256.
     """
     algorithm = "pbkdf2_sha256"
-    iterations = 10000
+    iterations = 12000
     digest = hashlib.sha256
 
     @password_max_length(MAXIMUM_PASSWORD_LENGTH)

django/contrib/auth/tests/test_hashers.py

@@ -52,7 +52,7 @@ class TestUtilsHashPass(unittest.TestCase):
     def test_pkbdf2(self):
         encoded = make_password('lètmein', 'seasalt', 'pbkdf2_sha256')
         self.assertEqual(encoded,
-            'pbkdf2_sha256$10000$seasalt$CWWFdHOWwPnki7HvkcqN9iA2T3KLW1cf2uZ5kvArtVY=')
+            'pbkdf2_sha256$12000$seasalt$Ybw8zsFxqja97tY/o6G+Fy1ksY4U/Hw3DRrGED6Up4s=')
         self.assertTrue(is_password_usable(encoded))
         self.assertTrue(check_password('lètmein', encoded))
         self.assertFalse(check_password('lètmeinz', encoded))
@@ -284,16 +284,16 @@ class TestUtilsHashPass(unittest.TestCase):
 
     def test_low_level_pkbdf2(self):
         hasher = PBKDF2PasswordHasher()
-        encoded = hasher.encode('lètmein', 'seasalt')
+        encoded = hasher.encode('lètmein', 'seasalt2')
         self.assertEqual(encoded,
-            'pbkdf2_sha256$10000$seasalt$CWWFdHOWwPnki7HvkcqN9iA2T3KLW1cf2uZ5kvArtVY=')
+            'pbkdf2_sha256$12000$seasalt2$hlDLKsxgkgb1aeOppkM5atCYw5rPzAjCNQZ4NYyUROw=')
         self.assertTrue(hasher.verify('lètmein', encoded))
 
     def test_low_level_pbkdf2_sha1(self):
         hasher = PBKDF2SHA1PasswordHasher()
-        encoded = hasher.encode('lètmein', 'seasalt')
+        encoded = hasher.encode('lètmein', 'seasalt2')
         self.assertEqual(encoded,
-            'pbkdf2_sha1$10000$seasalt$oAfF6vgs95ncksAhGXOWf4Okq7o=')
+            'pbkdf2_sha1$12000$seasalt2$JeMRVfjjgtWw3/HzlnlfqBnQ6CA=')
         self.assertTrue(hasher.verify('lètmein', encoded))
 
     def test_upgrade(self):

django/utils/crypto.py

@@ -139,11 +139,12 @@ def pbkdf2(password, salt, iterations, dklen=0, digest=None):
 
     HMAC+SHA256 is used as the default pseudo random function.
 
-    Right now 10,000 iterations is the recommended default which takes
+    As of 2011, 10,000 iterations was the recommended default which
-    100ms on a 2.2Ghz Core 2 Duo.  This is probably the bare minimum
+    took 100ms on a 2.2Ghz Core 2 Duo. This is probably the bare
-    for security given 1000 iterations was recommended in 2001. This
+    minimum for security given 1000 iterations was recommended in
-    code is very well optimized for CPython and is only four times
+    2001. This code is very well optimized for CPython and is only
-    slower than openssl's implementation.
+    four times slower than openssl's implementation. Look in
+    django.contrib.auth.hashers for the present default.
     """
     assert iterations > 0
     if not digest:

docs/internals/howto-release-django.txt

@@ -89,6 +89,13 @@ any time leading up to the actual release:
    key you'll use for the release, and should include patches for each issue
    being fixed.
 
+#. If this is a major release, make sure the tests pass, then increase
+   the default PBKDF2 iterations in
+   ``django.contrib.auth.hashers.PBKDF2PasswordHasher`` by about 10%
+   (pick a round number). Run the tests, and update the 3 failing
+   hasher tests with the new values. Make sure this gets noted in the
+   release notes (see release notes on 1.6 for an example).
+
 #. As the release approaches, watch Trac to make sure no release blockers
    are left for the upcoming release.
 

docs/releases/1.6.txt

@@ -365,6 +365,13 @@ Minor features
   a list (except on SQLite). This has long been possible (but not officially
   supported) on MySQL and PostgreSQL, and is now also available on Oracle.
 
+* The default iteration count for the PBKDF2 password hasher has been
+  increased by 20%. This backwards compatible change will not affect
+  existing passwords or users who have subclassed
+  `django.contrib.auth.hashers.PBKDF2PasswordHasher`` to change the
+  default value.
+
+
 Backwards incompatible changes in 1.6
 =====================================