Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1V1ZUF-00087z-52 for bitcoin-development@lists.sourceforge.net; Tue, 23 Jul 2013 10:06:31 +0000 Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of gmail.com designates 209.85.214.171 as permitted sender) client-ip=209.85.214.171; envelope-from=pieter.wuille@gmail.com; helo=mail-ob0-f171.google.com; Received: from mail-ob0-f171.google.com ([209.85.214.171]) by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1V1ZUE-0006ZY-Dz for bitcoin-development@lists.sourceforge.net; Tue, 23 Jul 2013 10:06:31 +0000 Received: by mail-ob0-f171.google.com with SMTP id dn14so9819190obc.30 for ; Tue, 23 Jul 2013 03:06:25 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.43.144.82 with SMTP id jp18mr18905388icc.100.1374573985072; Tue, 23 Jul 2013 03:06:25 -0700 (PDT) Received: by 10.50.20.225 with HTTP; Tue, 23 Jul 2013 03:06:24 -0700 (PDT) In-Reply-To: <201307231102.06693.andyparkins@gmail.com> References: <201307231052.14210.andyparkins@gmail.com> <201307231102.06693.andyparkins@gmail.com> Date: Tue, 23 Jul 2013 12:06:24 +0200 Message-ID: From: Pieter Wuille To: Andy Parkins Content-Type: text/plain; charset=ISO-8859-1 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 (pieter.wuille[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: 1V1ZUE-0006ZY-Dz Cc: Bitcoin Dev Subject: Re: [Bitcoin-development] HTTP REST API for bitcoind 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: Tue, 23 Jul 2013 10:06:31 -0000 On Tue, Jul 23, 2013 at 12:02 PM, Andy Parkins wrote: > On Tuesday 23 July 2013 10:56:02 Pieter Wuille wrote: > >> The block chain is not involved at all to verify transactions, it's >> just a historical >> record to serve to other nodes, and to do wallet rescans with. > > It must be involved to some extent. Certainly during a temporary fork, there > are two branches growing, and you have to be able, when verifying a new > transaction, to say which branch it's one... which branch of the blockchain. No, not really. The UTXO set is the state you need to validate blocks and transactions. You can see blocks as authenticated patches to the UTXO set (consumes some outputs, produces others). During validation, we store "undo data", basically (non-authenticated) reverse patches to the UTXO set, so we can walk back in case of a reorganization. -- Pieter