byte[] key = fillByteArray(20, 0x0b);
    String data = "Hi There";

    checkSha1("b617318655057264e28bc0b6fb378c8ef146be00", key, data);
  }

  public void testRfc2202_hmacSha1_case2() {
    byte[] key = "Jefe".getBytes(UTF_8);
    String data = "what do ya want for nothing?";

    checkSha1("effcdf6ae5eb2fa2d27416d5f184df9c259a7c79", key, data);
  }

  public void testRfc2202_hmacSha1_case3() {

    ImmutableSet<String> validIsatapAddresses =
        ImmutableSet.of(
            "2001:db8::5efe:102:304",
            "2001:db8::100:5efe:102:304", // Private Multicast? Not likely.
            "2001:db8::200:5efe:102:304",
            "2001:db8::300:5efe:102:304" // Public Multicast? Also unlikely.
            );
    ImmutableSet<String> nonIsatapAddresses =
        ImmutableSet.of(