I mean if you safe any file on the permanent storage by using an HDi application (for example capture a frame of a movie and save it to the hard disc) can this file be loaded or modified by another disc or can one disc only reach a defiened part of the permanent storage
thx
mikeret
Is there any kind of "secured storage" implemented in HD DVD specification ?
arro239
Each disc has a provider id (studio) and a content id (disc). When you write to persistent storage, you write to the content folder which is stored under the provider folder. A disc from one provider can not read/write to any of the folders of another provider.
Now, there is some ambiguity about discs from the same provider writing to the other content directories within the same provider directory. You will find that on the MS simulator and the TSB emulator, this is not allowed. The disc can only read/write one directory (based on its provider and content ids).
The spec is ambiguous on this topic, implying that *technically* a disc should be able to access any content directory within its provider. The benefit to allowing this is that a studio could release to related movies (part 1 and 2) and they could share information - bookmarks, screenshots, etc. But, this isnt how the player currently functions.
And, since the only way you can do any reading/writing at all requires that you have an aacs disc, you shouldn't be able to duplicate another discs provider and content ids and get access to stuff that you shouldn't.
a.s.viswa
You should not rely on data you save to the PS being unmodified. Although the MAC will prevent casual / accidental tampering, it is not foolproof. Also that doesn't keep anything secret; people can still read the file.
YoK
PStorage can only be accessed by the particular title: one title cannot mess with anothers storage. If you want to share things, there is a Common area that anyone can get to.
(This is for AACS titles only: non AACS titles cannot get to pstorage at all of course).
You can prevent modification of the files (e.g. on a PC where users can maybe get to them) by MAC-ing the files: if modified they won't load any more as the checksum won't match. The APIs to do this are in the AACS spec, not the HD DVD spec (see aacsla.com)