I would suggest that this falls more in the realm of a custom file
system, rather than a file system filter driver, since your goal has now
become to protect the file system meta data itself - something that
really requires cooperation with the file system.
Of course, this assumes you want a file system level solution at all - a
more practical solution is probably just to encrypt the entire logical
block device (volume) or physical block device (disk/partition). Then
nobody can read those directory contents without the appropriate keys.
Regards,
Tony
Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
http://www.osr.com
Looking forward to seeing you at the Next OSR File Systems Class April
4, 2004 in Boston!
-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Francesco
Sent: Friday, January 14, 2005 3:43 PM
To: ntfsd redirect
Subject: Re:[ntfsd] I want my filenames to be secret
May be I haven’t explain clearly.
Basically I want to crypt the name of
the files (for example in the folder Documents), so
that if you take out the hard disk from my pc,
you cannot see the original name of the files
unless you have the filter and a key.
Why ever crypting the names? Just use CryptGenRandom to invent
them, as
IE’s cache does, this is enough.
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com
----- Original Message -----
From: “Francesco Garelli”
> To: “Windows File Systems Devs Interest List”
> Sent: Thursday, January 13, 2005 9:50 PM
> Subject: [ntfsd] I want my filenames to be secret
>
>
>> hi all,
>>
>> I have a new problem to propose. I am writing a FS filter which
>> should crypt the names of the files contained in a specific folder.
>> So far I have found two viable strategies:
>>
>> 1) Crypt names in the IRP_MJ_CREATE and decrypt them in the
>> IRP_MJ_DIRECTORY_CONTROL. This approach normally works but it may
>> fail when using short names. In fact when I crypt a filename, the FS
>> builds a short name based on a hash which once decrypted does not map
>> to the corresponding short name.
>> The only solution I have found is to manually change the short name
>> each time I change the long one. The problem is that, as far as I
>> know, only Windows XP accepts a ZwSetInformationFile with the
>> FileShortName option.
>>
>>
>> 2) Crypt the structure of a directory while the system is writing it.
>> By filtering the IRP_MJ_WRITE, I have seen Windows writes the
>> structure through a usual paging IO. The problem is how to recognize
>> an operation that is concerned with the directory I want to crypt.
>> Also I wonder if this approach might produce side effects I don’t see
>> at the moment. I have seen the file objects that updates directory
>> structure (and FAT) are not created through a IRP_MJ_CREATE; I guess
>> they are built internally by the file system.
>>
>>
>> What is the best approach as far as you know?
>>
>>
>> Thanks.
>> Francesco Garelli, Ph.D.
>>
>>
>>
>> —
>> Questions? First check the IFS FAQ at
> https://www.osronline.com/article.cfm?id=17
>>
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>
>
>
—
Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17
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