The plain Text In the Cache.

NTFSD
1

Hi,all
Most of articles in news group told me that a encrypt/decrypt driver should
encrypt file in noncache write and decrypt in noncache read.
But in this case,the cache contain the plain text,small files can be got as
plain text via email,ftp,etc.
My current solution is:when driver received a cache read irq to read a
secret file,replace the cache read result with noncache content.Is this
correct way?

Appreciate any advice.

Murphy.W

2

> My current solution is:when driver received a cache read irq to read a

secret file,replace the cache read result with noncache content.Is this
correct way?

No. cached read is not the only way to get file’s content.
Try memory mapped files.

L.

3

To L.Z
Thanks for your reply first.
Yes,that’s the key.
My filter driver cause ms word work incorrect and it just read file via
memory maping.

Any advice?

4

No. You will not be able to support memory-mapped files this way.

Note: file encryption is intended only for the case if the machine or
hard disk will be physically stolen. To protect the data from unauthorized
access on a running OS, NTFS ACLs are enough.

–
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

“ntfsd” wrote in message news:xxxxx@ntfsd…
> Hi,all
> Most of articles in news group told me that a encrypt/decrypt driver should
> encrypt file in noncache write and decrypt in noncache read.
> But in this case,the cache contain the plain text,small files can be got as
> plain text via email,ftp,etc.
> My current solution is:when driver received a cache read irq to read a
> secret file,replace the cache read result with noncache content.Is this
> correct way?
>
> Appreciate any advice.
>
> Murphy.W
>
>
>