Security

Secure destruction of CD/DVD discs

The advent of CD and DVD writers has meant that we not only do we find ourselves with hundreds of coffee cup coasters thanks to CDs contained in junk mail, magazines and from old, defunct software but we too are in a position where we can make discs ourselves.  Test discs, discs that have gone wrong, backup discs, discs to take data to school or work ... the list is endless.  

Problem is - what do you do with them when you're done with them?  Coffee cup coasters used to be a popular choice but when there are limits to how many coasters any one person or family (and their extended family and friends) actually need.  Chucking them in the bin is another option but when the discs contain data backup then this isn't a secure thing to do because someone else could pick them up and read them - and believe you me, CDs are robust and can easily survive a trip to the landfill.

Here are some basic facts about CD and DVD discs.

  1. The data is not stored on the bottom of the plastic disc but on either the aluminium foil (for pre-made discs) or just underneath that in a dye substrate (for writable CD and DVD discs).
  2. To destroy a disk you ideally want to destroy the top layer, not the bottom.
  3. To guarantee that no data is recoverable you ideally need to destroy the entire disc.

Here are tips on how you can securely get rid of your old CD and DVD discs.

  1. Don't make backup discs a disposal issue - use rewritable discs.  These work for many write/rewrite cycles and can save you a lot of money.  However, they do eventually wear out (the dye that changes color on the surface breaks down) and eventually even these will need disposal.  Depending on such factors as how you store the disks etc, manufacturers claim that they can be re-written up to 1000 times.
  2. Encrypt your data on the disc. If you use an encryption program like PGP Desktop then it doesn't matter if the discs are readable to others because they won't be able to extract the data from the encrypted archives.
    Be careful when using this though and only use a reliable encryption application (such as PGP).  Never rely on the password function in applications such as Microsoft Word or Money for security.
  3. Burn the discs.  Works but makes a real mess and the fumes are nasty.
  4. Shred the discs.  Many commercial shredders are capable of shredding CDs.  This is another effective solution.
  5. Invest in a CD destroyer.  There are many solutions for example the PRIMERA DS360 CD SHREDDER or the Pressit CD Destroyer (but we found the latter to be very messy!)
  6. Get a pair of scissors and cut the disc.  
    NOTE:  Take great care when doing this so as not to cut yourself!  And always cut away from yourself.

    There are a few options you can use:
    1. Cut the disc in half, making sure that you cut it through the middle.
    2. Cut spokes in the disc.

      For added security you can give each one of the vanes that you end up with a 90º twist.  This twisting causes the top layer to crack and peel, making the disc unreadable.
    3. The more vanes you cut, the more effectively it is destroyed.

      As a final touch, you can chop it in half.

Remember - chucking old discs into the trash is insecure!  Destroy them before disposal and stay safe!

Adrian Kingsley-Hughes
Last updated: March 1st 2005
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