Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 5DE7B94E for ; Wed, 27 Jul 2016 10:53:30 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from server3 (server3.include7.ch [144.76.194.38]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id 942531EA for ; Wed, 27 Jul 2016 10:53:29 +0000 (UTC) Received: by server3 (Postfix, from userid 115) id B4BDA2E6064F; Wed, 27 Jul 2016 12:53:28 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, FSL_HELO_NON_FQDN_1 autolearn=ham version=3.3.1 Received: from Jonass-MacBook-Pro-2.local (84-73-208-41.dclient.hispeed.ch [84.73.208.41]) by server3 (Postfix) with ESMTPSA id C0B282D00697; Wed, 27 Jul 2016 12:53:27 +0200 (CEST) To: Jochen Hoenicke , Bitcoin Protocol Discussion References: <5797AC88.8030507@gmail.com> <5797C3A7.5030600@jonasschnelli.ch> From: Jonas Schnelli Message-ID: <579892A4.6030505@jonasschnelli.ch> Date: Wed, 27 Jul 2016 12:53:24 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="rj5VxNhNOEhdK0qgsbuMUg8Tj6BwlFiVt" Subject: Re: [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: Wed, 27 Jul 2016 10:53:30 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --rj5VxNhNOEhdK0qgsbuMUg8Tj6BwlFiVt Content-Type: multipart/mixed; boundary="mmtHtDkgGfQNM7Ln58LAheSAIBqhOWwKU" From: Jonas Schnelli To: Jochen Hoenicke , Bitcoin Protocol Discussion Message-ID: <579892A4.6030505@jonasschnelli.ch> Subject: Re: [bitcoin-dev] BIP proposal: derived mnemonics References: <5797AC88.8030507@gmail.com> <5797C3A7.5030600@jonasschnelli.ch> In-Reply-To: --mmtHtDkgGfQNM7Ln58LAheSAIBqhOWwKU Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable > But what are the alternatives? Put an expensive processor and a decent= > amount of memory in every hardware wallet to support scrypt? Use a > million iterations and just wait 10 minutes after entering you > passphrase? Or compute the secret key on your online computer instead?= What the Digital Bitbox team does, is, PBKDF2 the user entered passphrase on the computer with >20'000 iterations, then PBKDF2 again onchip with the 2048 rounds. If somebody manages to steal your backup (in that case a file/SDCard or printed PDF), it would at least required > 22'048 iterations to derive the key from a passphrase which I consider "stronger" then just using 2048 iterations. > Also, how many iterations are secure? A million? Then just add two > random lower-case letters to the end of your passphrase and you have a > better protection with 2048 iterations. I guess you shouldn't delegate KDF security to the user. But sure, this could help as well. This is part of the UI. On the other hand, forcing the user to select a long/more-secure passphrase will very likely lead to many funds get lost behind encryption because of lost/forgotten passphrases. > If you want to be able to use > your passphrase with cheap hardware and be protected against a high-end= > computer with multiple GPUs that is almost a mllion times faster, then > you have to choose a good passphrase. Or just make sure nobody steals > your seed; it is not a brainwallet that is only protected by the > passphrase after all. Agree. But IMO this fact should not be an excuse to reduce/use low iterations during KDF (especially SHA2 based KDFs). --mmtHtDkgGfQNM7Ln58LAheSAIBqhOWwKU-- --rj5VxNhNOEhdK0qgsbuMUg8Tj6BwlFiVt Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJXmJKkAAoJECnUvLZBb1PsNcMQAI3R9sfil/ImCp4DPIO5+5ih PfK+mRwIXfHgN/f0PBurvR2ULeMJ+46whZajBbrkMvoOkWtbJsCeYEe5pVWrEZF/ QUG5qM5+VnztVvLG4Rpb7XmwE+QOGBDJbR1vlTpCmLiQ8fZIcsCg9zkqMzW7pVtk hgVWXZVuoT6cYES+VqDZoRr2KU1D3m7o6Uv0R4JPVa8dcdBGK5oE5JpsTD8kV0lr TQfc18LiC2nyXxfPWBLEes6BgRMNDo6uwgKH+c6zCgGAN2QZi/RF+8cir1OsVzFg oHTu1qw0kPx8dsSO3sjM3EO1r6GOs+dHNDf4ORS171eZtaAwVBBNnFolyzr73/a9 aytJx1KqsbWEq2pfJ/sTLF3be9lbE1ZICjHu/lpZ/v53o/vhlqeRElBt5IfmaT6n nRAQ58IVI+rOMu2vpbmm5rgd9XnYtdqWravHYWKSjWwgM23xx6J72WYXU5d6whWG hAMYa8nOUrBtHZCHRQdFq/LVGx0iPksDS4wHWo9rE/RIGSx6mq0ITaGh0itLHHWA rNDVojUE+GMbOuuXOoBpZVC+CH+Pcs0RXxTMEkwGh7zx9Ew3ANHVOwE1LSiRhKZ8 /212TLi61AlUwrit+ap4s3hiyDZMqrK+Q9Yrqpq3G6HCJWqU8sB96JtiGGoSuTqw 20y+KlvVsZPEiXsn9STo =Ap4C -----END PGP SIGNATURE----- --rj5VxNhNOEhdK0qgsbuMUg8Tj6BwlFiVt--