deleting files from DVD/CD?

[tomos]

Is there any simple way to delete files from disc (DVD/CD)?

Situation is I realised some older backups I did on DVD have some info (passwords) that isnt encrypted.
I would like to keep the backups but delete the relevant files.

These discs would have been burned with multisession so arent "closed"
I've tried using nero express & ashampoo to delete a couple of files off disc without success
The only way I could find so far was to replace the files with other (less sensitive or encrypted) of the same name.
Which is too complicated for what its worth

any ideas??

thanks, tom

[Deozaan]

Copy the entire disc to DVD-RW and then just erase the files you don't want. Be sure to destroy the old disc, too.

You can't erase from a CD or DVD unless it's CDRW or DVDRW.

[Ampa]

AFAIK once the info is on the CD it is there for good. Even if you add a file with the same name, tho old file is still going to exist, and is therefore findable (there are tools out there that will read all sessions of a multi-burn disk, and hence find the original).

The only surefire way would be to re-burn the CD in question, without the offending files.

[hamradio]

My Alternate Solution:

You could also just go through changing passwords to everything that is unencrypted.  Then they would be wrong on the cd/dvd. 

[Cynic]

Copy the entire disc to DVD-RW and then just erase the files you don't want. Be sure to destroy the old disc, too.

You can't erase from a CD or DVD unless it's CDRW or DVDRW.

I may be completely wrong, but I don't believe that's the case. Even when you erase files on rewritable media, the files are still accessible with tools like IsoBuster, like Ampa said.

So, in response to Tomos' intial question, I believe the answer is "no".

[Hirudin]

My Alternate Solution:

You could also just go through changing passwords to everything that is unencrypted.  Then they would be wrong on the cd/dvd. 

That's probably not a bad idea anyway!

Hopefully none of the passwords are shared somehow...

[tomos]

Okay, that's good to know

I'll have to go through older backups & decide what to do with them - I can probably chuck a lot of them at this stage but I'm slow to do that.

Most of the passwords arent actually that important but I better have a good close look at that too 

thanks for the help folks 

[f0dder]

You indeed need to destroy the old discs.

Well, *theoretically*, I guess it should be possible to burn more grooves on a CD that's already burnt (ie., you can't "unburn the 1's", but you should be able to "burn the 0's to 1's"), but I dunno if there's any software that will allow this, and whether drive firmware allows it, etc. But it should be physically possible

[Carol Haynes]

I have a cheap electric gizzmo that you feed DVDs/CDs through and it destroys the writing surface by stamping pits all over the disk. I usually run them through half a dozen times. To recover the disc would require polishing out all the pits but that would be very difficult without specialist equipment and would probably make the protective plastic layer so thin that the recording surface would be damaged in the process. I bought it from Maplins (in the UK), I'd guess Tandy or similar in the US would have something similar. It is certainly much quicker than trying to cut up discs by hand.

I suppose you could get much the same effect with a hammer (save it for when you are really frustrated with something and let yiourself go).

[f0dder]

Be careful when using a hammer, splintered pieces of disc aren't good for your eyes.

A few seconds in a microwave works wonders, btw: [attachthumb=#]

[Carol Haynes]

Hammers ... fair point ...

Not for the microwave potentially!

[tomos]

I suppose you could get much the same effect with a hammer (save it for when you are really frustrated with something and let yiourself go).

A few seconds in a microwave works wonders, btw:

Hammers ... fair point ...

Not for the microwave potentially!

[mwb1100]

To recover the disc would require polishing out all the pits but that would be very difficult without specialist equipment and would probably make the protective plastic layer so thin that the recording surface would be damaged in the process.

The pits should be made on the label side of the disc - the recording layer rides between the plastic (polycarboate) and whatever's on the top of the label side of the disk.  This is why if you use stick-on CD labels, they'll often destroy the recording if/when they peel off (and one reason why many people consider stick-on labels a bad idea).  If the pits are made on the label side, they actually remove bits of the recording layer - no amount of polishing will bring that back.  I would expect that the 'CD shredder' would pit both sides to ensure the recording layer got destroyed.

Also, many paper shredders claim to be able to handle CDs.

I just cut then in half with a pair of scissors, but I never have to do more than a few at any particular time.

[Lashiec]

f0dder, that's one funky coaster

[f0dder]

f0dder, that's one funky coaster

It took ~3 seconds in the microwave to make it look like that... along with scary sounds from the microwave itself, and blue lightning bolts along the surface of the disc. Preeeeety funky stuff

[p3lb0x]

remember that the cd also was glowing orange