All adhoc MAC applications have been updated to use HMAC, using SHA1 to
generate unique keys for each application based on the SECRET_KEY, which is
common practice for this situation. In all cases, backwards compatibility
with existing hashes has been maintained, aiming to phase this out as per
the normal deprecation process. In this way, under most normal
circumstances the old hashes will have expired (e.g. by session expiration
etc.) before they become invalid.
In the case of the messages framework and the cookie backend, which was
already using HMAC, there is the possibility of a backwards incompatibility
if the SECRET_KEY is shorter than the default 50 bytes, but the low
likelihood and low impact meant compatibility code was not worth it.
All known instances where tokens/hashes were compared using simple string
equality, which could potentially open timing based attacks, have also been
fixed using a constant-time comparison function.
There are no known practical attacks against the existing implementations,
so these security improvements will not be backported.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@14218 bcc190cf-cafb-0310-a4f2-bffc1f526a37
Internet Explorer, up to at least version 7, allows only 4K cookie data *per
domain*, rather than per cookie, so we ensure that stored messages leave
some room for other cookies.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@12287 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This deprecates User.message_set in favour of a configurable messaging
system, with backends provided for cookie storage, session storage and
backward compatibility.
Many thanks to Tobias McNulty for the bulk of the work here, with
contributions from Chris Beaven (SmileyChris) and lots of code review from
Russell Keith-Magee, and input from many others. Also credit to the authors
of various messaging systems for Django whose ideas may have been pinched
:-)
git-svn-id: http://code.djangoproject.com/svn/django/trunk@11804 bcc190cf-cafb-0310-a4f2-bffc1f526a37
Russell Keith-Magee
Jannis Leidel
Adrian Holovaty
Luke Plant