Brasero could use isomd5sum for embedded checksum
Submitted by Kip
Assigned to Brasero maintainer(s)
Link to original bug (#707742)
Description
Brasero could optionally use isomd5sum for embedding a checksum directly into the image it prepares before burning.
The approach works by computing a series of checksums, along with a master checksum at the block level. These checksums are stored in the ISO 9660's 'Application Use' area in byte positions 884 to 1395. See section 8.4.32 of the Standard ECMA-119 - Volume and File Structure of CDROM for Information Interchange on how this is done safely.
http://www.ecma-international.org/publications/standards/Ecma-119.htm
The advantage of this approach is a user can verify a disc's integrity without requiring access to a separate file containing checksums or the source image, but can perform the verification directly on /dev/optical_media.
In addition, the verification process may be faster than checking each package at the file system level because the verification process, when done at the block level is a linear sequential operation from the beginning inner track to the outer most containing data. The approach more commonly done instead performs potentially random seeks after looking up physical sector locations that the file system provides when given a file name contained within a checksum list (e.g. MD5SUM).
From the tool's README:
isomd5sum provides a way of making use of the ISO9660 application data
area to store md5sum data about the iso. This allows you to check the
iso given nothing more than the iso itself.