On Thu, Nov 09, 2017 at 01:34:38 CET, Robert Nichols wrote: > On 11/08/2017 11:36 AM, Merlin Büge wrote: > >Hello all, ... > >I thought of TRIMing the SSD via 'blkdiscard' instead of using > >'ATA secure erase' after putting random data on it (twice, see [0]), > >but that should make no difference, since the SSD will most probably > >report all zeros for TRIMed sectors. Either way, the flash chips will > >contain all random data ... > > No, they won't. They will all be cleared. The whole point of TRIM or > blkdiscard is to allow the controller to clear the blocks of flash cells > so that they will be immediately available for writing when needed. > Writing random data to the flash cells and then immediately clearing them > is fairly pointless. All it does is mask any residue a cleared cell might > have of the last data it contained. People who need that level of > security don't ask about it here. And that is just it: To get any security benefit, the random data must be still there on a read-back. Hence the procedure is exactly the same as for a HDD: Write random data to disk and leave it there, no "secure" erase, no TRIM. Regards, 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 If it's in the news, don't worry about it. The very definition of "news" is "something that hardly ever happens." -- Bruce Schneier _______________________________________________ dm-crypt mailing list dm-crypt@xxxxxxxx http://www.saout.de/mailman/listinfo/dm-crypt
