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Python Enhancement Proposals

PEP 464 – Removal of the PyPI Mirror Authenticity API

Donald Stufft <donald at>
Richard Jones <richard at>
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This PEP proposes the deprecation and removal of the PyPI Mirror Authenticity API, this includes the /serverkey URL and all of the URLs under /serversig.


The PyPI mirroring infrastructure (defined in PEP 381) provides a means to mirror the content of PyPI used by the automatic installers, and as a component of that, it provides a method for verifying the authenticity of the mirrored content.

This PEP proposes the removal of this API due to:

  • There are no known implementations that utilize this API, this includes pip and setuptools.
  • Because this API uses DSA it is vulnerable to leaking the private key if there is any bias in the random nonce.
  • This API solves one small corner of the trust problem, however the problem itself is much larger and it would be better to have a fully fledged system, such as The Update Framework, instead.

Due to the issues it has and the lack of use it is the opinion of this PEP that it does not provide any practical benefit to justify the additional complexity.

Plan for Deprecation & Removal

Immediately upon the acceptance of this PEP the Mirror Authenticity API will be considered deprecated and mirroring agents and installation tools should stop accessing it.

Instead of actually removing it from the current code base (PyPI 1.0) the current work to replace PyPI 1.0 with a new code base (PyPI 2.0) will simply not implement this API. This would cause the API to be “removed” when the switch from 1.0 to 2.0 occurs.

If PyPI 2.0 has not been deployed in place of PyPI 1.0 by Sept 01 2014 then this PEP will be implemented in the PyPI 1.0 code base instead (by removing the associated code).

No changes will be required in the installers, however PEP 381 compliant mirroring clients, such as bandersnatch and pep381client will need to be updated to no longer attempt to mirror the /serversig URLs.


Last modified: 2022-01-21 11:03:51 GMT