Re[2]: transparent encryption file system driver enctrypted flag

NTFSD
1

> Is fs filter so difficult? :slight_smile:

Depends on what kind of fs filter. If you want to write
an “observation” FS filter, then it’s fairly easy and the examples
are in the WDK. As for any data-modification filter, then yes,
they are pretty complex and hard to do right.

L.

2

>>Is fs filter so difficult? :slight_smile:

One can decide on his own by considering few of the points(these are from my limited experience on similar driver).

Supporting all Applications which some time really behave differently.(try office 2K7 and a older office version, try wordpad and we can not say who uses them now).
*No* data corruption at all of any sort. I mean excel saying that it has recovered the file totally unacceptable.
No data loss even if user asked for a restart without saving the file first.
Issues with hybernation.
Switch user.
Recyclebin.
etc. etc. etc. :slight_smile:

The simple point was "go read the archives as they have plenty of details on this particular topic, problems, solutions, methods. Build your knowledge on that heap of information, enhance that with samples and docs from WDK and others resources. After this when a person decides he/she is good with kernel programming and have understand the basics completely. Now post a specific problem to the list and get a solution, (well I mean most probably) :slight_smile: "

Ladisalv just putted this in short and in another way. (May be because he already write this so many times in detail)

regards,
Aditya

3

Any form of data modifying file system filter or minifilter is difficult.
There are no samples in the WDK and AFAIK no really good ones available
anywhere on the Internet. The two most difficult are encryption and
compression with trying to do both bringing another level of complexity to
the design even if not to the code. Most designs for encryption are rather
pathetic and don’t handle key management properly.

If you are paranoid:

  1. Use a Smartcard with PKI built into the card.
  2. Use an authenticating server to validate the Smartcard and user.
  3. Use a different session/symmetric key for each file.
  4. Pass the encrypted session/symmetric key to the Smartcard to decrypt it
    using the private key.

“Ladislav Zezula” wrote in message news:xxxxx@ntfsd…
> Is fs filter so difficult? :slight_smile:

Depends on what kind of fs filter. If you want to write
an “observation” FS filter, then it’s fairly easy and the examples
are in the WDK. As for any data-modification filter, then yes,
they are pretty complex and hard to do right.

L.