@Test
public void createKey_multipleCallsCreateDifferentKeys() throws Exception {

  AesSivKeyFormat format = createAesSivKeyFormat(64);
  TreeSet<String> keys = new TreeSet<>();
  KeyTypeManager.KeyFactory<AesSivKeyFormat, AesSivKey> factory =
      new AesSivKeyManager().keyFactory();
  final int numKeys = 1000;
  for (int i = 0; i < numKeys; ++i) {
    keys.add(TestUtil.hexEncode(factory.createKey(format).toByteArray()));
  }
  assertThat(keys).hasSize(numKeys);
}