[Distutils] Replacing md5 hashes for packages on PyPI

[Ian Cordasco]

+1 from me as well

On Wed, Nov 12, 2014 at 1:41 PM, Donald Stufft <donald at stufft.io> wrote:
>
>> On Nov 12, 2014, at 2:34 PM, Alex Gaynor <alex.gaynor at gmail.com> wrote:
>>
>> Hi everybody!
>>
>> Right now, PyPI provides MD5 hashes for packages, which is used by pip to
>> check
>> for corruption in transit. I'd like to propose we replace MD5 with SHA256 for
>> PyPi, and move to deprecate MD5 support in pip and setuptools.
>>
>> Why should we do this? MD5 is broken. Collision resistance is totally 100%
>> uselessly busted, and pre-image resistance is mathematically broken; practical
>> attacks aren't known publicly, but it's reasonable to assume private attacks
>> are strong because (sing it with me): "Attacks only get better".
>>
>> So MD5 doesn't provide the guarantees one might expect; SHA256 is not
>> broken in
>> these ways. But it's not just not providing value, it's actively causing
>> problems: some machines, such as those with packages compiled to meet
>> FIPS-140-2 do not have MD5 available at all, and so pip's verification raises
>> an exception.
>>
>> While one might be inclined to find a way to silently support both machine
>> configurations, I'd like to instead say we should abhor any additional
>> configuration (whether user supplied or auto-detected) and instead simply
>> upgrade the hashes offered by PyPI, and begin the deprecation process for
>> MD5
>> in pip.
>>
>> There are currently 60 packages on PyPI which are *not* hosted on PyPI, but
>> do
>> have MD5 hashes there. For these packages we could download the package,
>> verify
>> the MD5 hash, and then upgrade what PyPI stores to be SHA256.
>
>
> +1 from me.
>
> Security wise pip supported sha256 before it supported TLS so for pip anything
> that has the ability to securely fetch the sums from the /simple/ pages has
> the ability to use sha256. For setuptools there was a small window where
> setuptools implemented TLS verification (0.7) and implemented the support for
> things other than MD5 (0.9). However I don’t think this small window represents
> a large (or any?) number of users.
>
> IOW the impact should be non-existent other than having better digests.
>
> ---
> Donald Stufft
> PGP: 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA
>
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