Open Stack

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

Log:
commit 97baff182e2d742dff8061aa31489352b410a481
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.
    
    SecurityImpact
    DocImpact
    
    Change-Id: I8d7f43fb4c0573ac3681147eac213b369bbbcb3b