Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 1B26240F for ; Fri, 15 Sep 2017 08:55:40 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from relay4-d.mail.gandi.net (relay4-d.mail.gandi.net [217.70.183.196]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id A2474195 for ; Fri, 15 Sep 2017 08:55:39 +0000 (UTC) X-Originating-IP: 178.19.221.38 Received: from [10.10.42.104] (unknown [178.19.221.38]) (Authenticated sender: thomasv@electrum.org) by relay4-d.mail.gandi.net (Postfix) with ESMTPSA id F056B1720AF for ; Fri, 15 Sep 2017 10:55:37 +0200 (CEST) To: "bitcoin-dev@lists.linuxfoundation.org" From: Thomas Voegtlin Message-ID: <34198916-cde9-c84d-ca41-9feb8956bd80@electrum.org> Date: Fri, 15 Sep 2017 10:55:37 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-0.7 required=5.0 tests=RCVD_IN_DNSWL_LOW autolearn=disabled version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Subject: [bitcoin-dev] proposal: extend WIF format for segwit 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, 15 Sep 2017 08:55:40 -0000 The Wallet Import Format (WIF) currently appends a 0x01 byte after the raw private key, when that key needs to be used in conjunction with a compressed public key. This allows wallets to associate a single Bitcoin address to a WIF key. It would be useful to extend the semantics of that byte, to signal for segwit scripts, because these scripts result in different addresses. That way, a WIF private key can still be associated to a single Bitcoin address. What WIF currently does is: Nothing -> uncompressed pubkey 0x01 -> compressed pubkeys, non-segwit (can be used in P2PKH or P2SH) We could extend it as follows: 0x02 -> segwit script embedded in P2SH (P2WPKH or P2WSH) 0x03 -> native segwit script (P2WKH or P2WSH) Note 1: This is similar to my {x,y,z}{pub,prv} proposal for bip32 extended keys. (see other thread) Note 2: It is probably not useful to use distinct bytes for P2WKH and P2WSH, because the P2SH script is not known anyway. We did not do it for non-segwit addresses, I guess we should keep it the way it is. Note 3: we could also use a bech32 format for the private key, if it is going to be used with a bech32 address. I am not sure if such a format has been proposed already. Note 4: my proposal will not result in a user visible change at the beginning of the string, like we have for compressed/uncompressed. This could be improved.