Open Stack

Hi, I'd like you to take a look at this patch for potential
SecurityImpact.
https://review.openstack.org/357202

Log:
commit 077ac1896decbd738ac83dff28b5ad882274038c
Author: Peter Hamilton <peter.hamilton at jhuapl.edu>
Date:   Thu Aug 18 08:50:38 2016 -0400

    Add certificate validation
    
    This change adds support for a certificate trust store. When
    performing signature verification, all certificates in the trust
    store are loaded into a certificate verification context. This
    context is used to validate the signing certificate, verifying
    that the certificate belongs to a valid certificate chain rooted
    in the trust store.
    
    The get_verifier function is updated to accept an additional,
    optional parameter: trust_store_path. This parameter should
    contain a valid filesystem path to the directory acting as the
    certificate trust store. If not provided, it defaults to None
    and the trust store will be considered empty.
    
    For more information on this work, see the spec:
    https://review.openstack.org/#/c/357151/
    
    SecurityImpact
    DocImpact
    
    Change-Id: I8d7f43fb4c0573ac3681147eac213b369bbbcb3b