Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 8EA50C50 for ; Wed, 29 Aug 2018 09:54:30 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ua1-f45.google.com (mail-ua1-f45.google.com [209.85.222.45]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 1F01B12E for ; Wed, 29 Aug 2018 09:54:30 +0000 (UTC) Received: by mail-ua1-f45.google.com with SMTP id y10-v6so2852491uao.4 for ; Wed, 29 Aug 2018 02:54:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=DG92c0s//ap0yZz+aGOr1arQoWzZlDImu1iy1nrxemI=; b=TDYcAEGmrIJjdyh6cWClU+dNL8RP+URHCcjORae/XQX8AGQHraGYU3bYqV+FPzU1zR mPamBgoNm7IjHdFCj5JEUdi0e59lio4Al/oI8o5sX2X/PleaMXxlH86E/Oke0q8ZU6AC qcGhaRFdA6s1ZFCgoFz7fF8bH2zfrwaiTWj6D18tXCXMO5i4u3E4R2X/LmoD8WZ86Gbp SGxP7ZowXnZlABaqlmBImKT8H6H5ywbJnlVDs5U9I+g3/23uVGZhBBqZmuQWTZmL7pPA 0MRkb4/dopXbv+/aufd7C5hCE06BdTyy89BaYHLclSxb75dAqELosIGvOlpUwht+WgMS 0fPw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=DG92c0s//ap0yZz+aGOr1arQoWzZlDImu1iy1nrxemI=; b=N6IhK74JhuVSTFstDzb4k1PBAJxZoO479lGXdS2pWe8o1X+NdMnhluE4MjDPO4q/l0 8ml56xtOObERy+qtt4SQMj8yhfgtmeiXlVAo/e6309GWUenKxH9FZTeyy7ATl+SzZewn 4d93QsxML0CmlCDvLxubI9sW5fq3AJqRn+/Rkmx75k5G3pmO+EOSj+WZmzONLwR6oEfe NpCKwHDB0DwP1lJp8XU6GOdk5UAsLmnaY5W0j9eh01Y7qawRE1NF/ThY16vREQqXXVmy udhJs9tKMgil40WhNJoT6ELzAYh45wVTZNRzTDSlLAO182P//Vxnro1VJI9Kvv74EHL1 SROg== X-Gm-Message-State: APzg51ByWAtQMkc6BIPz7G6zQkPa8QC9rBtA5zcIlqCP3h8lw6dGAcqv 8A9AS3UdNOra8cfjlQGTJEkG6OAG/0M7yQKhtl+llYYi X-Google-Smtp-Source: ANB0VdbtYnwNP58BW7chJ8Bg4MAGIESvravmDTQUSXifWKEkqRBX4ihI/YOulcQ4AE6JiH1DvJz1DiUOLIYnkXjIAjU= X-Received: by 2002:a9f:386a:: with SMTP id q39-v6mr3685836uad.196.1535536468901; Wed, 29 Aug 2018 02:54:28 -0700 (PDT) MIME-Version: 1.0 From: Zawy Date: Wed, 29 Aug 2018 05:54:17 -0400 Message-ID: To: bitcoin-dev@lists.linuxfoundation.org Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Wed, 29 Aug 2018 11:08:09 +0000 Subject: Re: [bitcoin-dev] Getting around to fixing the timewarp attack. X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 29 Aug 2018 09:54:30 -0000 Rather than restricting every timestamp (or just the 2016*N+1 timestamps) to >= 1+ the previous timestamp as recorded on the blockchain, the difficulty calculation could have the same restriction but only in how the timestamps are used. I don't know about backwards compatibility. Either way, this would also prevent the powLimit attack that is also capable of getting "unlimited" blocks in less than 4 weeks of > 50% selfish mining. LTC, BCH, and LTC fixed to the "Zeitgeist" or "timewarp" attack on GeistGeld in 2011 described by Artforz in different ways, but all are still vulnerable by the powLimit attack that I described here: https://github.com/zawy12/difficulty-algorithms/issues/30 Other solutions may not prevent this other attack.