Date: Fri, 29 Jul 2005 12:36:55 +0200 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Benjamin Lutz <benlutz@datacomm.ch> Cc: current@freebsd.org Subject: Re: GELI - disk encryption GEOM class committed. Message-ID: <20050729103655.GG609@darkness.comp.waw.pl> In-Reply-To: <42E981B9.5060500@datacomm.ch> References: <20050728205413.GB762@darkness.comp.waw.pl> <42E95E08.80006@datacomm.ch> <42E981B9.5060500@datacomm.ch>
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--nhYGnrYv1PEJ5gA2 Content-Type: text/plain; charset=iso-8859-2 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jul 29, 2005 at 03:09:13AM +0200, Benjamin Lutz wrote: +> > GELI is different than GBDE. It offers different features, but it also +> > use different scheme for doing crypto work. +>=20 +>=20 +> I tried to find out what exactly the differences are. Please correct me +> where I'm wrong: +>=20 +> Encryption Strength: +> GELI - Supports AES, Blowfish, 3DES for data encryption, with a +> different key per sector. Access key is PKCS #5 protected. +> (What does this mean regarding a brute force attack?) No. The encryption key is the same. Every data block is encrypted using choosen encryption algorithm in CBC mode and with per-block unique IVs. PKCS#5v2 basically takes your passphrase and makes huge number of HMAC/SHA512 rounds with it. The result is used as a key. When brute forcing, you need to take a passphrase, do the same HMAC/SHA512 work and result use as a key to try. It works really great as passphrase protection. On my laptop it takes about 1 second to make 2^16 HMAC/SHA512 operations. +> Speed: +> GBDE - Runs in software. +> GELI - Support for crypto(9) hardware. Blowfish is faster than AES. This was one of the main GELI goals, that's why simple sector-to-sector encryption is used, so geli doesn't add disk overhead. +> Booting from Encrypted Root: +> GELI - Works. How'd one load the kernel from an encrypted root though? Kernel has to be loaded from a USB Pen-Drive or a CD-ROM. You need to put /boot/ directory in there. GELI will ask for the passphrase before root file system is mounted. After that you can remove Pen-Drive/CD-ROM. +> The GBDE manpage warns that the on-disk format might be changed in the +> future. What about GELI? It'd be unpleasant to upgrade the OS and then +> find out that the encrypted volume is no longer accessible. It will be changed only in case of security flaw. +> How much throughput can one expect in practice, say, compared to the +> numbers in "openssl speed"? Depends on your disk speed, but you should just try it. --=20 Pawel Jakub Dawidek http://www.wheel.pl pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! --nhYGnrYv1PEJ5gA2 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (FreeBSD) iD8DBQFC6gbHForvXbEpPzQRAnegAJ9X93eZd+0k7tra/LYHOnn+tAa2MACg2UDG HUBKQP0k8e28fD1vdpwmqig= =DnnO -----END PGP SIGNATURE----- --nhYGnrYv1PEJ5gA2--
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