On Thu, Jan 27, 2011 at 03:06:39PM CET, Eduardo M KALINOWSKI <edua...@kalinowski.com.br> said: > On Qui, 27 Jan 2011, Celejar wrote: > >>Now another question, which nobody seems to have noticed/mentioned. > >> > >>Since CBC encryption is a "recursive algorithm, the encryption of the n-th > >>block requires the encryption of all preceding blocks, 0 till n-1." [1] > >>Now, does it mean if my HD has a bad block in the middle, then all the > >>remaining data will be gone entirely? > >> > >>1. http://clemens.endorphin.org/LinuxHDEncSettings > > > >This seems correct - Wikipedia also says that with CBC: > > > >"Note that a one-bit change in a plaintext affects all following > >ciphertext blocks." > > > >http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Cipher-block_chaining_.28CBC.29 > > That is correct, but the whole disk is not one single CBC-encoded > unity. The link in the question message says that: > > [...] CBC chaining is cut every sector and restarted with a new > initialisation vector (IV), so we can encrypt sectors individually. > The choice of the sector as smallest unit matches with the smallest > unit of hard disks, where a sector is also atomic in terms of access. > > http://clemens.endorphin.org/LinuxHDEncSettings
take a look to the output of cryptsetup luksDump. Here it says XTS-plain64 is used. See http://en.wikipedia.org/wiki/Disk_encryption_theory for explanations on disk encryption schemes. CBC would be a very bad idea for random access and modification. -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20110127154039.gd12...@rail.eu.org