def trusted?(pem)
      if cert = OpenSSL::X509::Certificate.new(pem) rescue nil
        @store.verify(cert).tap do |trusted|
          @store.add_cert(cert) if trusted rescue nil
        end
      end
    end
def trusted?(pem)
      if cert = OpenSSL::X509::Certificate.new(pem) rescue nil
        @store.verify(cert).tap do |trusted|
          @store.add_cert(cert) if trusted rescue nil
        end
      end
    end
Return true if the certificate is signed by a CA certificate in the
 store. If the certificate can be trusted, it's added to the store so
 it can be used to trust other certs.