def get_verifier(context, img_signature_certificate_uuid, img_signature_hash_method, img_signature, img_signature_key_type):
 image_meta_props = {'img_signature_uuid': img_signature_certificate_uuid, 'img_signature_hash_method': img_signature_hash_method, 'img_signature': img_signature, 'img_signature_key_type': img_signature_key_type}
 for key in image_meta_props.keys():
  if (image_meta_props[key] is None):
   raise exception.SignatureVerificationError(reason=(_('Required image properties for signature verification do not exist. Cannot verify signature. Missing property: %s') % key))
 signature = get_signature(img_signature)
 hash_method = get_hash_method(img_signature_hash_method)
 signature_key_type = SignatureKeyType.lookup(img_signature_key_type)
 public_key = get_public_key(context, img_signature_certificate_uuid, signature_key_type)
 verifier = signature_key_type.create_verifier(signature, hash_method, public_key)
 if verifier:
  return verifier
 else:
  raise exception.SignatureVerificationError(reason=_('Error occurred while creating the verifier'))

def get_verifier ( context , img_signature_certificate_uuid , img_signature_hash_method , img_signature , img_signature_key_type ) : image_meta_props = { 'img_signature_uuid' : img_signature_certificate_uuid , 'img_signature_hash_method' : img_signature_hash_method , 'img_signature' : img_signature , 'img_signature_key_type' : img_signature_key_type } for key in image_meta_props . keys ( ) : if ( image_meta_props [ key ] is None ) : raise exception . SignatureVerificationError ( reason = ( _ ( 'Required image properties for signature verification do not exist. Cannot verify signature. Missing property: %s' ) % key ) ) signature = get_signature ( img_signature ) hash_method = get_hash_method ( img_signature_hash_method ) signature_key_type = SignatureKeyType . lookup ( img_signature_key_type ) public_key = get_public_key ( context , img_signature_certificate_uuid , signature_key_type ) verifier = signature_key_type . create_verifier ( signature , hash_method , public_key ) if verifier : return verifier else : raise exception . SignatureVerificationError ( reason = _ ( 'Error occurred while creating the verifier' ) )
instantiate signature properties and use them to create a verifier .