Just added this to the Wiki-Version of the FAQ as Item 2.19, if anybody wants to have a look and comment. Arno On Tue, Mar 18, 2014 at 03:33:51 CET, Arno Wagner wrote: > On Mon, Mar 17, 2014 at 19:55:05 CET, Cpp wrote: > > Hello, > > > > I noticed a lot of online articles recommend to overwrite your hard > > disk with random data before creating an encryption volume on it. > > Normally this is done by: > > > > # dd if=/dev/urandom of=/dev/sda bs=4096 > > This is slooooooooooow.... ;-) > > > This will of course take a while, and there is also the badblocks > > alternative. However recently I've seen another approach that uses an > > encrypted (non-luks) container that is later filled with blank data. > > It's said that this approach is much faster than the urandom method > > above. > > I came up with that when I had to securely wipe 50 disks > a few years ago. Other people may have had a similar idea. > > > I haven't used this yet, so I hope I got the command line > > right: > > > > # cryptsetup -c aes-xts-plain64 -h sha512 -s 512 -d /dev/urandom open > > /dev/sda --type plain cryptroot > > Make ist easier on you, the defaults are really quite enough: > > # cryptsetup create -d /dev/urandom /dev/sda cryptroot > > > # dd if=/dev/zero of=/dev/mapper/cryptroot bs=4096 > > And you can get a progress meter like this: > > # dd_rescue -w /dev/zero /dev/mapper/cryptroot > > or like this > > # cat /dev/zero | wcs > /dev/mapper/cryptroot > > (uses my sream-meter "wcs" from: http://www.tansi.org/tools/index.html) > > > My question is are there any serious drawbacks of using this method in > > place of the urandom one? > > None. > > Arno > -- > Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@xxxxxxxxxxx > GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D 9718 > ---- > A good decision is based on knowledge and not on numbers. - Plato > _______________________________________________ > dm-crypt mailing list > dm-crypt@xxxxxxxx > http://www.saout.de/mailman/listinfo/dm-crypt -- Arno Wagner, Dr. sc. techn., Dipl. Inform., Email: arno@xxxxxxxxxxx GnuPG: ID: CB5D9718 FP: 12D6 C03B 1B30 33BB 13CF B774 E35C 5FA1 CB5D 9718 ---- A good decision is based on knowledge and not on numbers. - Plato _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx http://www.saout.de/mailman/listinfo/dm-crypt
