Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1WMSzx-0005mp-PI for bitcoin-development@lists.sourceforge.net; Sun, 09 Mar 2014 01:57:53 +0000 Received-SPF: pass (sog-mx-1.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.215.53 as permitted sender) client-ip=209.85.215.53; envelope-from=gmaxwell@gmail.com; helo=mail-la0-f53.google.com; Received: from mail-la0-f53.google.com ([209.85.215.53]) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1WMSzw-0005jL-Tz for bitcoin-development@lists.sourceforge.net; Sun, 09 Mar 2014 01:57:53 +0000 Received: by mail-la0-f53.google.com with SMTP id b8so3744421lan.26 for ; Sat, 08 Mar 2014 17:57:46 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.152.4.68 with SMTP id i4mr17493553lai.8.1394330266352; Sat, 08 Mar 2014 17:57:46 -0800 (PST) Received: by 10.112.189.164 with HTTP; Sat, 8 Mar 2014 17:57:46 -0800 (PST) In-Reply-To: <201403081934.12035.luke@dashjr.org> References: <53174F20.10207@gmail.com> <201403081934.12035.luke@dashjr.org> Date: Sat, 8 Mar 2014 17:57:46 -0800 Message-ID: From: Gregory Maxwell To: Luke-Jr Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Spam-Score: -1.6 (-) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (gmaxwell[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-Headers-End: 1WMSzw-0005jL-Tz Cc: Bitcoin Development Subject: Re: [Bitcoin-development] New side channel attack that can recover Bitcoin keys X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 09 Mar 2014 01:57:53 -0000 On Sat, Mar 8, 2014 at 11:34 AM, Luke-Jr wrote: > On Wednesday, March 05, 2014 4:21:52 PM Kevin wrote: >> How can we patch this issue? > No need, it is not an issue for Bitcoin. > Properly used, there is only ever one signature per public key. Security shouldn't depend on perfect use. There are many things that result in multiple key use: Bitcoin address authentication (something which the pool you created uses!), someone spamming you with multiple payments to a common address which you didn't solicit (what, are you just going to ignore the extra coins?), ... or just practical considerations=E2=80=94 I note the mining pool you founded continually pays= a single address for 'fall back' payments when it can't pay in the coinbase transact, I know you consider that a bug, but its the reality today. Most security issues aren't the result of one problem but several problems combined, so it's important to make each layer strong even if the strength shouldn't be important due to proper use in other layers. Fortunately, libsecp256k1 has a nearly constant time/constant memory access multiply for signing which should reduce exposure substantially (and is generally built in a way that reduces vulnerabilities).