On Thu, 29 Dec 2011 04:04:17 +0100 Christian Heimes <li...@cheimes.de> wrote: > Am 29.12.2011 02:37, schrieb Jesse Noller: > > Back up link for the PDF: > > http://dl.dropbox.com/u/1374/2007_28C3_Effective_DoS_on_web_application_platforms.pdf > > > > Ocert disclosure: > > http://www.ocert.org/advisories/ocert-2011-003.html > > >From http://www.nruns.com/_downloads/advisory28122011.pdf > > --- > Python uses a hash function which is very similar to DJBX33X, which can > be broken using a > meet-in-the-middle attack. It operates on register size and is thus > different for 64 and 32 bit > machines. While generating multi-collisions efficiently is also possible > for the 64 bit version > of the function, the resulting colliding strings are too large to be > relevant for anything more > than an academic attack. > > Plone as the most prominent Python web framework accepts 1 MB of POST > data, which it > parses in about 7 minutes of CPU time in the worst case. > This gives an attacker with about 20 kbit/s the possibility to keep one > Core Duo core > constantly busy. If the attacker is in the position to have a Gigabit > line available, he can keep > about 50.000 Core Duo cores busy. > --- > > If I remember correctly CPython uses the long for its hash function so > 64bit Windows uses a 32bit hash.
Not anymore, Py_hash_t is currently aligned with Py_ssize_t. Regards Antoine. _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
