### Question:
Encrypt { public static String encrypt(final String source, final String key, final Encryptor encryptor) throws GeneralSecurityException { return encrypt(source, key, encryptor, Charsets.UTF_8); }  static String encrypt(final String source, final String key, final Encryptor encryptor); static String encrypt(final String source, final String key, final Encryptor encryptor,
            final Charset charset); static String decrypt(final String source, final String key, final Decryptor decryptor); static String decrypt(final String source, final String key, final Decryptor decryptor,
            final Charset charset); static final String DEFAULT_KEY; }### Answer:
@Test public void testMd5() throws GeneralSecurityException { String source = "123456789"; String encode = Encrypt.encrypt(source, null, Md5.INSTANCE); Assert.assertEquals(encode, "25F9E794323B453885F5181F1B624D0B"); }