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 BED8C92B for ; Tue, 26 Jul 2016 18:31:41 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-wm0-f46.google.com (mail-wm0-f46.google.com [74.125.82.46]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id B4C01259 for ; Tue, 26 Jul 2016 18:31:40 +0000 (UTC) Received: by mail-wm0-f46.google.com with SMTP id f65so184678572wmi.0 for ; Tue, 26 Jul 2016 11:31:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=to:from:subject:message-id:date:user-agent:mime-version :content-transfer-encoding; bh=fuPSvWxMdNaFisqS12ZSU8DNkfthbdEfTjP1Jn2TkRA=; b=i24aWkioIl78JDVRMXGjjU/OVTVUOra33k4bS4fT/XCueXYOic/CB5JbOHUv+gWK2a gnBRjjsWcsW4VLfMjBmgyBwjXFfUb34tSyjvGpyb7sLmnd9TlRODozCLu0CEzcQFzZSM BJ85AdmW0jbVC8s0VRkbRQUDc+U14wj2DFyFy8tSlTQXX42JgEzmZ35+kDpRKf8bKOGK jZuAJVCnOyJ72pNPJIlygiOlDMUM9z0v+fcu8tk6QB8HIr+gxKXhDpytcIQbSjInqJNn ItTix4gbwYToUhlyN4eTv/arkbnO4UVw1zU5OQzoi/LY7GEaEQBp22F9sVkQgd0yhZpa 0sZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:to:from:subject:message-id:date:user-agent :mime-version:content-transfer-encoding; bh=fuPSvWxMdNaFisqS12ZSU8DNkfthbdEfTjP1Jn2TkRA=; b=CxGXJzj9aCZwf+wLnwn7HuokJkEiQiD4Bg1VI/HUYuoU9yabztgoZYE0/L+4lYndqa ngPANSLc7PeCWPp5lkilINAT7+ZEzDR6QUvUTJr0wRX5EtM3GB3vdiroCavpYl1BzgdY /HKW1xmPB9qXb6hqqlZjfysF7xtEkgEif6ebxU+AOamdHkN/KsvnbWFrB1uLD0QmYx2t 4v5NJhfwBIPUQus/JkQxfNlzBbAwVAOTnvB0zKvMjFmYjuHRtPAe5SOhkIVKsumTMLKc p18A/Ka7H2RMEI9K+7032fc6loSFY6mGiZQ3nWFmsPhlat52bv7uKWTllfzSx4Rlhbpg JF5Q== X-Gm-Message-State: AEkooutgLBjX0hy0MatpFlfsjqyMpRC/y+U1c+fMdAVeSXx+Ovz+z4bUyOINFw/xOCp69g== X-Received: by 10.28.41.131 with SMTP id p125mr24605774wmp.15.1469557899005; Tue, 26 Jul 2016 11:31:39 -0700 (PDT) Received: from [192.168.178.13] (52D9D6D7.cm-11-1d.dynamic.ziggo.nl. [82.217.214.215]) by smtp.googlemail.com with ESMTPSA id f10sm2268383wje.14.2016.07.26.11.31.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 26 Jul 2016 11:31:38 -0700 (PDT) To: bitcoin-dev@lists.linuxfoundation.org From: millibitcoin Message-ID: <5797AC88.8030507@gmail.com> Date: Tue, 26 Jul 2016 20:31:36 +0200 User-Agent: Mozilla/5.0 (X11; Linux i686; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, 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 X-Mailman-Approved-At: Tue, 26 Jul 2016 18:44:46 +0000 Subject: [bitcoin-dev] BIP proposal: derived mnemonics 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: Tue, 26 Jul 2016 18:31:41 -0000 (not sure so sent again after subscribing (one use case added)) Dear Bitcoin developers, Below is provided a draft BIP proposal for a master mnemonic sentence from which other mnemonics sentences can be derived in a deterministic non-reversible way (on an offline computer). This would make it much easier to split funds into smaller fractions and use those in a HD-wallet when appropriate (just by inserting 12 or more words), without ever putting the master mnemonic at risk on an online computer. But there are many more use cases. A reference implementation, specifically for use with a Trezor, has been generated and can be found at: http://thebitcoinecosystem.info/DerivedMnemonics.html I'm not a professional programmer or cryptographer, so the idea and reference implementation will probably need a lot of reviewing but I do think Bitcoin needs this extension and the corresponding ease of use and improved security model. In the hope you like the idea, Regards, sumBTC 
   BIP: ???
   Title: Derived mnemonics from a master mnemonic.
   Author: sumBTC 
   Status: For Discussion
   Type:
   Created: 2016-07-24
==Abstract== This BIP??? uses a master mnemonic sentence, as described in BIP39, for the deterministic generation of derived mnemonic sentences. The derived mnemonics are of the same format as the master mnemonic but can consist of a higher or lower number of words. Binary seeds can then be generated for derived mnemonics (and master mnemonic) as described in BIP39. Each of these seeds can be used to generate deterministic wallets using BIP-0032 or similar methods. ==Motivation== A mnemonic code or sentence is superior for human interaction as described in BIP39 and can, for example, be written on paper or even memorized. However, once a mnemonic has been used online, even through the use of a hardware wallet, the mnemonic could be compromised. This should be considered a bad practice from a security standpoint. We therefore propose the generation of a master mnemonic offline and from this generate (also offline) multiple derived mnemonics in a deterministic way for online use. The master mnemonic is never used online and the master mnemonic cannot be obtained from the derived mnemonics. Examples of use cases are described below. ==Generating the master mnemonic== The master mnemonic is first derived as a standard mnemonic as described in BIP39. ==From master mnemonic to derived mnemonics== From the master mnemonic a new string is created: string = MasterMnemonic + " " + Count + " " + Strength; Here, MasterMnemonic are the space separated words of the master mnemonic. Count = 0, 1, 2 denotes the different derived mnemonics of a given strength and Strength = numWords / 3 * 32, where numWords is the number of words desired for the derived mnemonic and only integer arithmetic is used in the calculation (e.g. for numWords = 14, Strength = 128). Both Count and Strength are converted to strings. This string is then hashed using sha512: hash = sha512(string); and turned into a byte array: for (var i=0; i>> ((i%4)*8)) & 0b11111111; } This byte array is then used to generate a new mnemonic as shown in the reference implementation using the method described in BIP39. The core of the new code in the reference manual can be found by jumping to "start: new code" in the reference software. A passphrase for the master mnemonic has the same effect on the derived mnemoncis (so must be included). ==Reference Implementation== The reference implementation generates addresses based on BIP44 for a 24 word master mnemonic and is available from http://thebitcoinecosystem.info/DerivedMnemonics.html or github (not yet) ==Checking the derived mnemonics using Electrum== The displayed addresses in each of the reference implementations can be easily checked using Electrum in the following manner: move the directory ~/.electrum to a backup directory. start Electrum and choose: Restore a wallet or import keys Hardware wallet Restore Electum wallet from device seed words TREZOR wallet Insert one of the mnemonics and check that the same addresses are generated by Electrum Check the private keys: move the directory ~/.electrum to a backup directory. start Electrum and choose: Restore a wallet or import keys Standard wallet Import one of the private keys and check that the correct address has been generated. Some checks should include a passphrase. ==Examples of Use Cases== A person with 25 bitcoin splits funds using 5 derived mnemonics and sends 5 bitcoins to the first address of each derived mnemonic. He can then use a (hardware) HD-wallet and simply insert one of the derived mnemonics to put only 5 bitcoins online and at risk at once. All funds can be recovered from the master mnemonic. A person wants to give 10 bitcoin to each of his family members, giving each participant a derived mnemonic and sending bitcoin to each of them. The donating person can always recover the derived mnemonic if one of his family members loses his derived mnemonic. For his Trezor wallet, someone wants to memorize only a 12 words master seed but wants to insert a 24 words derived seed so a key logger on his computer has 24! possibilities to check and not 12! (not a possibility for the current reference implementation but trivial to add).