public static byte[] pubKeyTweakMul(byte[] pubkey, byte[] tweak) throws AssertFailException{
        Preconditions.checkArgument(pubkey.length == 33 || pubkey.length == 65);

        ByteBuffer byteBuff = nativeECDSABuffer.get();
        if (byteBuff == null || byteBuff.capacity() < pubkey.length + tweak.length) {