public static BigInteger publicKeyFromPrivate(BigInteger privKey) {
        ECPoint point = publicPointFromPrivate(privKey);

        byte[] encoded = point.getEncoded(false);
        return new BigInteger(1, Arrays.copyOfRange(encoded, 1, encoded.length)); // remove prefix
    }
@Test
    public void testPublicKeyFromPrivateKey() {
        assertEquals(Sign.publicKeyFromPrivate(SampleKeys.PRIVATE_KEY), (SampleKeys.PUBLIC_KEY));
    }