enable hash randomization by default
diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst
index 85953ad..3fb0bf6 100644
--- a/Doc/reference/datamodel.rst
+++ b/Doc/reference/datamodel.rst
@@ -1277,7 +1277,29 @@
inheritance of :meth:`__hash__` will be blocked, just as if :attr:`__hash__`
had been explicitly set to :const:`None`.
- See also the :option:`-R` command-line option.
+
+ .. note::
+
+ Note by default the :meth:`__hash__` values of str, bytes and datetime
+ objects are "salted" with an unpredictable random value. Although they
+ remain constant within an individual Python process, they are not
+ predictable between repeated invocations of Python.
+
+ This is intended to provide protection against a denial-of-service caused
+ by carefully-chosen inputs that exploit the worst case performance of a
+ dict insertion, O(n^2) complexity. See
+ http://www.ocert.org/advisories/ocert-2011-003.html for details.
+
+ Changing hash values affects the order in which keys are retrieved from a
+ dict. Although Python has never made guarantees about this ordering (and
+ it typically varies between 32-bit and 64-bit builds), enough real-world
+ code implicitly relies on this non-guaranteed behavior that the
+ randomization is disabled by default.
+
+ See also :envvar:`PYTHONHASHSEED`.
+
+ .. versionchanged:: 3.3
+ Hash randomization is enabled by default.
.. method:: object.__bool__(self)