Issue #19254: Provide an optimized Python implementation of PBKDF2_HMAC
diff --git a/Doc/library/hashlib.rst b/Doc/library/hashlib.rst
index 3bf30bb..677d530 100644
--- a/Doc/library/hashlib.rst
+++ b/Doc/library/hashlib.rst
@@ -212,7 +212,11 @@
.. versionadded:: 3.4
- .. note:: *pbkdf2_hmac* is only available with OpenSSL 1.0 and newer.
+ .. note:: A fast implementation of *pbkdf2_hmac* is only available with
+ OpenSSL 1.0 and newer. The Python implementation uses an inline
+ version of :mod:`hmac` and is about three times slower. Contrary to
+ OpenSSL's current code the length of the password has only a minimal
+ impact on the runtime of the Python implementation.
.. seealso::