Open Stack

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

Log:
commit a42ba7b25580ffafbe0821601dc76303add625e2
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 signature_utils.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.
    
    All new certificate utility code is added in a new module named
    certificate_utils.
    
    For more information on this work, see the spec:
    https://review.openstack.org/#/c/357151/
    
    SecurityImpact
    DocImpact
    
    Change-Id: I8d7f43fb4c0573ac3681147eac213b369bbbcb3b