Hello All,
Is there any way to find out whether the file is encrypted or Non Encrypted
without adding headers .
I just finished an Encrypt decrypt file system filter driver thanks to so
much gurus here…But i just finished it wihtout adding headers.
I just saw that if we add headers we have to deal with the faking of file
sizes and did a through study in the group.
However is there any way apart from addding headers by which we can
determine whether the file is encrypted or not?
I tried using a Attribute FILE_aTTRIBUTE_ENCRYPTED and it works great but
unfortunately only for NTFS and not for FAT.
Someone suggested me using EXTENDED ATTRIBUTES. But i could not find any
info on it.
Could someone give me a hint whether this is possible?
Thank you very much
Regards
Shal.
Shal,
Recognition is always one of the main issues. If you use EA’s then there
will be a hole for FAT32 as well if you use Alternate data streams, this is
only for NTFS. Hence you need to come up with some type of persistent
storage on a per file basis to support all native filesystems.
You can keep some type of recoverable cache with the name information for
encrypted files, though for this type of named based solution you need to
deal with shortnames as well, quite the headache.
As soon as you get away from persistent storage attached to each file, such
as an EA or an ADS, then you are falling back to a name based policy, which
always have their own problems. It comes back to implementing a header or a
tail to store this information. Usually a tail is easier to implement
because you don’t have to worry about alignment but you still need to keep
it consistent on disk but there are still the size faking issues. This
latter issue, even though it is quite tricky to get right, is not
insurmountable.
Hope this helps,
Pete
Kernel Drivers
Windows Filesystem and Device Driver Consulting
www.KernelDrivers.com
(303)546-0300
-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Shalini
Sent: Monday, May 16, 2005 7:24 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] Encrypted/ Non Encrypted Files Detection.
Hello All,
Is there any way to find out whether the file is encrypted or Non Encrypted
without adding headers .
I just finished an Encrypt decrypt file system filter driver thanks to so
much gurus here…But i just finished it wihtout adding headers.
I just saw that if we add headers we have to deal with the faking of file
sizes and did a through study in the group.
However is there any way apart from addding headers by which we can
determine whether the file is encrypted or not?
I tried using a Attribute FILE_aTTRIBUTE_ENCRYPTED and it works great but
unfortunately only for NTFS and not for FAT.
Someone suggested me using EXTENDED ATTRIBUTES. But i could not find any
info on it.
Could someone give me a hint whether this is possible?
Thank you very much
Regards
Shal.
Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
You are currently subscribed to ntdev as: xxxxx@kerneldrivers.com
To unsubscribe send a blank email to xxxxx@lists.osr.com
Thank you very much Pete!
I shall do a study on adding tails…
I think thats the only solution that works for everything independent of
file systems etc.,
Thank you very much…
Regards,
Shal.
“Peter Scott” wrote in message
news:xxxxx@ntdev…
>
> Shal,
>
> Recognition is always one of the main issues. If you use EA’s then there
> will be a hole for FAT32 as well if you use Alternate data streams, this
> is
> only for NTFS. Hence you need to come up with some type of persistent
> storage on a per file basis to support all native filesystems.
>
> You can keep some type of recoverable cache with the name information for
> encrypted files, though for this type of named based solution you need to
> deal with shortnames as well, quite the headache.
>
> As soon as you get away from persistent storage attached to each file,
> such
> as an EA or an ADS, then you are falling back to a name based policy,
> which
> always have their own problems. It comes back to implementing a header or
> a
> tail to store this information. Usually a tail is easier to implement
> because you don’t have to worry about alignment but you still need to keep
> it consistent on disk but there are still the size faking issues. This
> latter issue, even though it is quite tricky to get right, is not
> insurmountable.
>
> Hope this helps,
>
> Pete
>
> Kernel Drivers
> Windows Filesystem and Device Driver Consulting
> www.KernelDrivers.com
> (303)546-0300
>
>
> -----Original Message-----
> From: xxxxx@lists.osr.com
> [mailto:xxxxx@lists.osr.com] On Behalf Of Shalini
> Sent: Monday, May 16, 2005 7:24 AM
> To: Windows System Software Devs Interest List
> Subject: [ntdev] Encrypted/ Non Encrypted Files Detection.
>
> Hello All,
> Is there any way to find out whether the file is encrypted or Non
> Encrypted
> without adding headers .
> I just finished an Encrypt decrypt file system filter driver thanks to so
> much gurus here…But i just finished it wihtout adding headers.
> I just saw that if we add headers we have to deal with the faking of file
> sizes and did a through study in the group.
> However is there any way apart from addding headers by which we can
> determine whether the file is encrypted or not?
> I tried using a Attribute FILE_aTTRIBUTE_ENCRYPTED and it works great but
> unfortunately only for NTFS and not for FAT.
> Someone suggested me using EXTENDED ATTRIBUTES. But i could not find any
> info on it.
>
> Could someone give me a hint whether this is possible?
>
> Thank you very much
> Regards
> Shal.
>
>
>
> —
> Questions? First check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@kerneldrivers.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>
>
>