From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 905888D4 for ; Fri, 20 May 2016 14:31:03 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-qg0-f44.google.com (mail-qg0-f44.google.com [209.85.192.44]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id E7D151EE for ; Fri, 20 May 2016 14:31:02 +0000 (UTC) Received: by mail-qg0-f44.google.com with SMTP id j18so12919641qge.2 for ; Fri, 20 May 2016 07:31:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=5tvwWqe0775GAWtLaa03WveNNlfY3tVH7Cx+2cJfUeI=; b=IXp4931uEV5E96FruBbJXjutXAZL5sKcOMUIs53Vik9zWC/msjt27dSJS0kpFGyHBc PPYWp+2xXgg6DHQ1IBDVxU7/MsNeGzxK+/0FG3Var88t85fvxRjekKDdCXp81PWxon7F pUFGA7jDwJzv2ieLTqRzNMLJBpX6hANPYltN+xK9BX1hqjrSdrNgtQL03UacJsF0zAR4 Syj8GRv+yIX1oIP6+pqOUKuW685+CJUC8GEu9PS6IfPVeUBDxBPUuGnjznxvCy1Vaskv kDJSN4lyTr8mBCvHJmoaeQlUg/VHQjk6USFq4cNvSEArkCr2POk97vbihIWiPpob0aoG d+rg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=5tvwWqe0775GAWtLaa03WveNNlfY3tVH7Cx+2cJfUeI=; b=d5V8fGMTdLGFXNnsqN2kDiNvKr19uMnd1A0kHDVFiVXMvX1yKEeHKT1YXDDDueoQcx t5kRZDhK46dXuyNfi+oBlDsKeksTcKlRnZ1eWJVqGQiGlvhewZKCHSa92jWQEYzvAJ0v 4gzPwcFKUqLX73xHe4zaAbAMPwQZ1M7QalW1X6KUzAGYUDQeblOIvo0t6cYE7DNY2Jlp djPHT5FfKLS1dh30UIViNKQeIroFHDIp+G1mMkG6WNI8a8haFWiIOHnLM5XdqxbVpDjb ba2mAOTUzSkupScor9y/Nk6wciEN0gDW+THsV7XWYg4hFz3CfZnFA0LDZYUzn0zEK1E0 dQ4A== X-Gm-Message-State: AOPr4FV48o7Y/5QTxR77VYLdgWsiCk4ridLFcsG8gSiz2P+N+qQcfww6yy7tQquHF3yeRS86Xciv4yBrMbg2Hg== X-Received: by 10.140.201.143 with SMTP id w137mr3674336qha.66.1463754662186; Fri, 20 May 2016 07:31:02 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: James MacWhyte Date: Fri, 20 May 2016 14:30:52 +0000 Message-ID: To: Johnson Lau , Bitcoin Protocol Discussion , Matthew Roberts Content-Type: multipart/alternative; boundary=001a11426766ad94bb053346f05b X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Subject: Re: [bitcoin-dev] BIP: OP_PRANDOM 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: Fri, 20 May 2016 14:31:03 -0000 --001a11426766ad94bb053346f05b Content-Type: text/plain; charset=UTF-8 Matthew, Other than gambling, do you have any specific examples of how this could be useful? On Fri, May 20, 2016, 20:34 Johnson Lau via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > Using the hash of multiple blocks does not make it any safer. The miner of > the last block always determines the results, by knowing the hashes of all > previous blocks. > > > == Security > > Pay-to-script-hash can be used to protect the details of contracts that > use OP_PRANDOM from the prying eyes of miners. However, since there is also > a non-zero risk that a participant in a contract may attempt to bribe a > miner the inclusion of multiple block hashes as a source of randomness is a > must. Every miner would effectively need to be bribed to ensure control > over the results of the random numbers, which is already very unlikely. The > risk approaches zero as N goes up. > > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > --001a11426766ad94bb053346f05b Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

Matthew,

Other than gambling, do you have any specific examples of ho= w this could be useful?


On Fri, May 20, 2016, 20:34= Johnson Lau via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
U= sing the hash of multiple blocks does not make it any safer. The miner of t= he last block always determines the results, by knowing the hashes of all p= revious blocks.


=3D=3D Security

Pay-to-script-hash can be used to protect the details of contracts that use OP_PRANDOM from the prying eyes of miners. However, since there is also a non-zero risk that a participant in a contract may attempt to bribe a miner the inclusion of multiple block hashes as a source of randomness is a must. Every miner would effectively need to be bribed to ensure control over the results of the random numbers, which is already very unlikely. The risk approaches zero as N goes up.


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