It is possible to burn a DVD/CD?BDR such that there is a hidden file system within the disc using the slack space that is not mapped onto the disc. So this is how it works: -R discs are not used in this hack, but rather discs known as -RW's ("rewritables") where you can write the disc multiple times. Though I suppose it would be possible to do this all on a -R disc, but that would take a whole new level of a hack. Anyhow the main files on the disc are bunt first and finalized, and at the outer rings of the disc using a non-standard file system or no file system at all, with just the file data being written. Now lets say that the disc has 8.5 gigs of data with 2 gigs of data used, that is 6.5 gigs of stego data. A second layer of obfuscation would be to have each part of the disc having some data recorded to it, if only a bunch of zeros or ones, so when the person who picks up the disc doesn't see two separate parts of the disc recorded, but rather a continual full-disc burn look on the bottom of the recordable disc. .

This isn't only the case with optical media, but has been mostly proven to work with the 2MF floppy disc space expander. That tech allows for 1.9 megs that actually works for safely storing data.on floppy discs.

Needless to say but I will say it anyway, the secret data block should be encrypted without any headers. Personally I would suggest using VeraCrypt for packaging of this data.

You now have a brief outline, now let's see you code it under the GNU GPL Version 2. w00h00!

Cheers!
-warmfuzzy

... When all else fails, read the instructions

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Re: Data Offset on Media
By: warmfuzzy to All on Fri Aug 15 2025 05:51 pm

It is possible to burn a DVD/CD?BDR such that there is a hidden file system within the disc using the slack space that is not mapped onto the disc. So this is how it works: -R discs are not used in this hack, but rather discs known as -RW's ("rewritables") where you can write the disc multiple times.

I wonder if you could create an extended filesystem on rewriteable media? Create an extended partition as a container, then create a visible partition and a "hidden" partition filled with junk. That would get you the full "looking" DVD.

I think of some of the cool things Veracrypt does, like having containers within containers, encrypting entire devices - and wonder if some of those tricks would be possible?

Being able to mount what looks like free space on a drive as an encrypted volume would be wild.
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