[Python-Dev] Fast Implementation for ZIP decryption

Collin Winter collinw at gmail.com
Mon Aug 31 06:28:49 CEST 2009

On Sun, Aug 30, 2009 at 7:34 AM, Shashank
Singh<shashank.sunny.singh at gmail.com> wrote:
> just to give you an idea of the speed up:
> a 3.3 mb zip file extracted using the current all-python implementation on
> my machine (win xp 1.67Ghz 1.5GB)
> takes approximately 38 seconds.
> the same file when extracted using c implementation takes 0.4 seconds.

Are there any applications/frameworks which have zip files on their
critical path, where this kind of (admittedly impressive) speedup
would be beneficial? What was the motivation for writing the C

Collin Winter

> On Sun, Aug 30, 2009 at 6:35 PM, <exarkun at twistedmatrix.com> wrote:
>> On 12:59 pm, steve at pearwood.info wrote:
>>> On Sun, 30 Aug 2009 06:55:33 pm Martin v. Löwis wrote:
>>>> > Does it sound worthy enough to create a patch for and integrate
>>>> > into python itself?
>>>> Probably not, given that people think that the algorithm itself is
>>>> fairly useless.
>>> I would think that for most people, the threat model isn't "the CIA is
>>> reading my files" but "my little brother or nosey co-worker is reading
>>> my files", and for that, zip encryption with a good password is
>>> probably perfectly adequate. E.g. OpenOffice uses it for
>>> password-protected documents.
>>> Given that Python already supports ZIP decryption (as it should), are
>>> there any reasons to prefer the current pure-Python implementation over
>>> a faster version?
>> Given that the use case is "protect my biology homework from my little
>> brother", how fast does the implementation really need to be?  Is speeding
>> it up from 0.1 seconds to 0.001 seconds worth the potential new problems
>> that come with more C code (more code to maintain, less portability to other
>> runtimes, potential for interpreter crashes or even arbitrary code execution
>> vulnerabilities from specially crafted files)?
>> Jean-Paul
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