OpenID Libraries should be stateless

[Kevin Turner]

On Tue, 2008-02-05 at 12:32 +0100, Wichert Akkerman wrote:
> Never ever use pickles for something like that: the pickle format is not
> just a marshalling format: a pickle can contain arbitraty python code
> which is executed when the pickle is unpacked. That means that using
> pickles opens an easy attack vector into your application.

This is a good point.  But regardless of the particulars of the
marshalling format, if you're trusting the user-agent to store it, you
need to make sure it's not tampered with while it's there.  So it should
be signed or encrypted.  And once you've made it tamper-proof, pickle's
vulnerabilities are less relevant.