Browse Prior Art Database

Rendering Compact Disk-Recordable Written Disks as Unusable

IP.com Disclosure Number: IPCOM000118817D
Original Publication Date: 1997-Jul-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Power, BR: AUTHOR [+2]

Abstract

Compact Disk-Recordable (CD-R) disks are easy to generate. However, these write-once disks become a nuisance when they are no longer wanted and they contain sensitive data. Thus, disclosed is a multi-step process for dealing with unwanted CD-R disks.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 53% of the total text.

Rendering Compact Disk-Recordable Written Disks as Unusable

      Compact Disk-Recordable (CD-R) disks are easy to generate.
However, these write-once disks become a nuisance when they are no
longer wanted and they contain sensitive data.  Thus, disclosed is a
multi-step process for dealing with unwanted CD-R disks.

      First, a security S-bit in the name of files.  This S-bit could
be set to 1, meaning that the file must be destroyed when no longer
wanted, or 0, meaning that the file is totally non-confidential and
need not be destroyed.  Files with S=1 could be totally (100%)
overwritten before further action was taken on the CD-R or Digital
Versatile Disk-Recordable (DVD-R).

Then, the algorithm for destroying the data on the disk would consist
of:
  1.  Read the table of contents on the disk for each session
       on each layer of the disk.  Each table of contents gives
       the location of a respective recording area.
  2.  Read the volume descriptor (directory) in each recording
       session (track) on each layer of the disk.  This begins
       at the 16th block of each track for CD.
  3.  Search for files in each directory with the S bit equal
       to 1.  Overwrite these files with a Pulse Width Modulation
       (PWM) pattern.  The user could select the PWM density, from
       10% to 100%.  100% would be preferred.  Setting the S bit
       to 1 is a user option to be used when the user wanted to
       eradicate his/her most sensitive data one track at a
       time.  This S=1 step is optional and might not be needed
       for most users.
  4.  Overwrite the volume descriptor (directory) of each
       recording session with the above PWM pattern.  This...