[Distutils] wheel file signatures scheme

[Alex Clark]

On 2012-09-03 11:24:32 +0000, Daniel Holth said:

> On Mon, Sep 3, 2012 at 2:15 AM, Ronald Oussoren 
> <ronaldoussoren at mac.com> wrote:
>> 
>> On 22 Aug, 2012, at 4:52, Daniel Holth 
>> <dholth at gmail.com> wrote:
>> 
>>> I've made what I think is exciting progress on the digital signatures
>>> design for wheel (updated built/binary packages for Python; intended
>>> to replace egg). The insight is that we can overload the "extras"
>>> syntax as a convenient way to mention the public key we expect:
>>> 
>>> package[extra, ed25519=ouBJlTJJ4SJXoy8Bi1KRlewWLU6JW7HUXTgvU1YRuiA]
>> 
>> Why this hack instead of providing explict syntax for this?
> 
> It's because it can be made to be backwards-compatible. Declare that
> your package provides the extra "ed25519=key" and
> non-signature-verifying setuptools won't complain. I like the idea of
> using array indexing [] for "which package? the one signed with a
> particular key."
> 
>> Also the format doesn't seem to have any way to verify the validity of 
>> the signing key,
>> the documentation even says that "key distribution is out of scope for 
>> this spec". That's
>> odd for feature that's intended to add security.
>> 
>> Why did you decide to use JSON Web Signatures instead of PGP 
>> signatures, or even
>> X.509 signatures? With the latter two the key distribution problem is 
>> already solved, and
>> PGP signatures are used a lot in the opensource world.
> 
> I wanted to use Ed25519, an elliptic-curve signatures system that has
> 32-byte public keys and a very fast (~100k cycle) implementation. I
> wanted to be able to generate throwaway keys in 2.5 milliseconds and
> use them to verify transfers between a build server and an
> installation, and have keys represent the build server or the package,
> not necessarily a person. I wanted to include the entire signing and
> verifying system in Python instead of relying on an external package.
> 
> Currently so few Python packages are signed that popular opinion is
> that signing isn't supported at all (it is). I think part of the
> problem is that PGP is totally inconvenient. A new system gives us the
> opportunity to try to make signing so effortless that publishers are
> more likely to provide us with signed packages.
> 
> Key distribution is outside the scope of the wheel spec which just
> says how signatures are included in the file. I think we are figuring
> out some elegant solutions though, the first being "a PGP-signed
> e-mail containing package[ed25519=key] lines" (distributed by the
> publisher of a Python application that has dependencies). Signed wheel
> archives include the verifying key as part of the signature. Maybe
> PyPI will eventually provide a place for it too.


Good answer :-)

> 
> Thanks,
> 
> Daniel


-- 
Alex Clark · http://pythonpackages.com