Real-time File Encryption VxD:
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This sample demonstrates how to install file system hook and
encrypt/decrypt the files on-the-fly. I have written it in C++
so that it can be adapted easily to write any other type of file
hooker. The encryption algorithm used here is very elementary
(1's complement). Implementing an industry strength encryption
algorithm, e.g., DES, Blowfish, etc., in file hook is pretty
complex and beyond the scope of this sample VxD.

When loaded into memory this VxD will encrypt/decrypt all the
files written to or read from "C:\ENCRFILE" directory (hard
coded into VxD) transparently. To load this VxD dynamically you
can use TestVxD.Exe program provided with this library. To load
it statically create an entry (device=fcrypt.vxd) in "[386enh]"
section of the system.ini file and copy the VxD into Windows
system directory and restart the Windows.

To build VxD, change directory paths of DDK, SDK, MSVC++, etc., in
the "tools" section of the MAKEFILE to their appropriate paths on
your machine, execute NMAKE command from DOS-prompt or open FCrypt.mdp
project file in MSDev Studio.
