[Catalog-sig] PyPI mirror key rollover

Tarek Ziadé ziade.tarek at gmail.com
Thu Apr 28 11:27:14 CEST 2011

On Wed, Apr 27, 2011 at 8:39 PM, "Martin v. Löwis" <martin at v.loewis.de> wrote:
> I came up with a key rollover scheme for the server key on PyPI.
> The objective of this key rollover is to protect against brute-force
> attacks of people trying to crack the key. If the main server itself
> gets compromised (and the private key leaks), this scheme will not
> help, and we will need to reset the package database back to a
> known-safe point in time.
> The idea is this: At any point in time, two keys are known - the
> "current" key, and the "new" key,
> https://pypi.python.org/serverkey
> https://pypi.python.org/serverkey.new
> There will be a key rollover every year on July 1st. At this point,
> the "new" key becomes current, and a new "new" key is generated and
> published.
> Tools using the mirror infrastructure are encouraged to hard-code
> (cache) both keys in their code base, and attempt validation of
> a "simple" page against each of them. If both validations fail,
> either the keys are outdated, or the mirror they are using has been
> compromised. In this case, they should fall back to not using
> mirrors, but contact the master directly.
> After a key rollover, mirrors will need some time to refetch the
> signatures for all "simple" pages, so the old current key may
> be needed some time after the key rollover still. Within one
> day, all mirrors should have caught up.
> Also after a key rollover, tools should update their cached copies
> of the keys, and produce new releases. Users will then have one
> year to upgrade their tools to continue to use the mirror
> infrastructure. Tools may also chose to offer users to update
> the serverkeys (after due validation), or may chose to download
> them automatically, in which case they should validate the https
> server certicate for authenticity of the keys.
> The key rollover will be logged in the PyPI journal,
> using an empty package name and an empty release. TOOLS USING
> NAMES. Earlier today, such a journal entry was already added;
> I took it out again when I noticed that some tools actually
> do need to be fixed.
> Unless some flaws are detected in this scheme, I'll do the first
> key rollover this coming July.

I have another suggestion,
what about adding a new response header on https://pypi.python.org/serverkey ?

Like "X-Key-Rollover: some date"

> Regards,
> Martin
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Tarek Ziadé | http://ziade.org

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