public int size()
    {
        return sha1.digest().length;
    }
@Test
    public void testSize()
    {
        byte[] buf = new byte[1024];
        Arrays.fill(buf, (byte) 0xAA);

        ZDigest digest = new ZDigest();

        digest.update(buf);
        int size = digest.size();
        assertThat(size, is(20));
    }