@Test
public void createKey_multipleTimes() throws Exception {

  AesCmacPrfKeyManager manager = new AesCmacPrfKeyManager();
  AesCmacPrfKeyFormat keyFormat = makeAesCmacPrfKeyFormat(32);
  assertThat(manager.keyFactory().createKey(keyFormat).getKeyValue())
      .isNotEqualTo(manager.keyFactory().createKey(keyFormat).getKeyValue());
}