Python now uses SipHash24 on all major platforms.

CryptGenRandom()

Issue #18756: os.urandom() now uses a lazily-opened persistent file descriptor, so as to avoid using many file descriptors when run in parallel from multiple threads.

are now created non-inheritable; add functions os.get/set_inheritable(),
os.get/set_handle_inheritable() and socket.socket.get/set_inheritable().

Issue #18756: Improve error reporting in os.urandom() when the failure is due to something else than /dev/urandom not existing.

Drop SDK version configuration for Tk compilation, to not bind it to W2k
anymore. Binding it to XP would conflict with Tk's own binding of tkMenu to W2k.

This was a regression caused by the hash randomization patch.

This was a regression caused by the hash randomization patch.

This was a regression caused by the hash randomization patch.

  environment variable, to provide an opt-in way to protect against denial of
  service attacks due to hash collisions within the dict and set types.  Patch
  by David Malcolm, based on work by Victor Stinner.

in order to make algorithmic complexity attacks on (e.g.) web apps much more complicated.

The environment variable PYTHONHASHSEED and the new command line flag -R control this
behavior.