[upon_drumhead]

Can you describe what you mean by plausible deniability if in your example you can prove from any of the individual Shufflecake volumes that there's X amount of data in the others?

3-volume Shufflecake setup with on a 100 gb device. I put 10 gigabytes into #1, 20 gigabytes in #2 and so in #3, I can only store 70 gb of data before I get I/O errors, which leaks that there's 30 gigabytes of data in the other volumes.

[tomgag]

Yes, but only if you have all three opened, i.e., you are in a "home alone scenario". Remember that Shufflecake volumes have a hierarchy, i.e. volume 1 is "less secret" than volume 2, which is "less secret" than volume 3, etc. In your example, during an interrogation, you would only open volume 1 and maybe volume 2, but not volume 3. You would see that volume 1 has 10 GB of data, volume 2 has 20 GB, and you can still write 70 GB before getting I/O errors. Nothing hints at the fact that there is a 3rd volume. Of course, in so doing, you will actually overwrite and corrupt volume 3, but this is desired behavior. That's why we recommend of always opening all volumes for the "home alone" scenario.

[upon_drumhead]

Thank you for that clarification.

Another question about this, presume #1 10 gb, #2 20 gb, #3 35 gb

We have #1 and #2 open, #3 is taking 50% of the 'free space' shown. Is writing data in #1 or #2 have a roughly 50% chance of destroying data in #3 or does it known mapped blocks and the overwrite only happens once the actual free amount is used up?

[tomgag]

Roughly 50% chance of messing up with data in #3.

There is the possibility of reducing a bit this chance at the cost of wasting more space by using error-correction, e.g. with RAID, if so desired. This is explained in the paper and in the FAQ and the README.