On Thu, Jun 03, 2010 at 10:48:18PM +0200, Luca Berra wrote: > On Thu, Jun 03, 2010 at 10:14:53PM +0200, Arno Wagner wrote: >> On Thu, Jun 03, 2010 at 09:05:59PM +0300, Panagiotis Malakoudis wrote: >>> OK, I looked a bit more inside LUKS specification and I now know that the >>> 128KB keyslot is actually the 32byte master key AF-split to 128KB and then >>> encoded with my key. A single bit of change in these 128KB makes key >>> invalid. >>> >>> Now that I know all this, I consider the LUKS format fundamentally flawed to >>> data corruption. >> >> It is. However this area should not be written by anything except >> cryoptsetup. If you look closely basically every filesystem >> and partition scheme is about as vulnerable. The thing is, >> modern disks do not suffer single bit corruption easily. More >> likely are whole lost sectors. > > well, actually if you look closely at modern filesystems and > partitioning schemes, you will find there are more than one copy of > critical metadata. > ext2 has a backup superblock GPT partition has a secondary header and > table at the other end of the > disk > > we really miss an on-disk backup of the LUKS header. However the partition table does not have a backup at all. It is a trade-off. Security-wise, an on-disk backup is a risk. Makeing a backup manually is not that hard. Maybe a function on cryptsetup or a contributed script could make it easier, but that is about it. If you do, on the other hand, a sector-wise backup of the encrypted partition, you not only get the LUKS header, but also protect all the data against a disk failure. Keeping in mind that disk failure roughly has 5% annual probability per disk, that backup is non-optional in the first place.... Arno -- Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno@xxxxxxxxxxx GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F ---- Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans 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
