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[Python-Dev] Python 3.6 dict becomes compact and gets a private version; and keywords become ordered

Gregory P. Smith greg at krypto.org
Mon Sep 12 18:59:47 EDT 2016 
On Mon, Sep 12, 2016 at 3:57 PM Brett Cannon <brett at python.org> wrote:

> On Mon, 12 Sep 2016 at 15:46 Ethan Furman <ethan at stoneleaf.us> wrote:
>
> On 09/12/2016 09:27 AM, Gregory P. Smith wrote:
>
> > For the regular dict (non kwargs or namespace __dict__) use case I would
> actually like to /see disorder preserved during iteration/.
> >
> > If we don't, we will eventually to find ourselves in a similar state we
> were in pre hash-randomization:
>
> Does anyone have a short explanation of the interaction between hash
> randomization and this new always ordered dict?  Why doesn't one make the
> other useless?
>
>
> There is still a hash table that stores a pointer into an array that
> stores the keys/values that are kept in an ordered array. So that
> first-level hash table still uses hash randomization.
>

More specifically: If the goal of hash randomization is to reduce DDOS hash
table stuffing attacks, that is still true. The hashing is randomized.

Dict ordering may actually _help_ DDOS protection. It no longer leaks
information potentially revealing details about the hash seed via the
iteration order.

-gps
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