def _verify_signature(message, signature, certs):
 for pem in certs:
  verifier = Verifier.from_string(pem, is_x509_cert=True)
  if verifier.verify(message, signature):
   return
 raise AppIdentityError('Invalid token signature')

def _verify_signature ( message , signature , certs ) : for pem in certs : verifier = Verifier . from_string ( pem , is_x509_cert = True ) if verifier . verify ( message , signature ) : return raise AppIdentityError ( 'Invalid token signature' )
verifies signed content using a list of certificates .