RE: Hard Drive Encrypting

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To: "Allan Foster" <AllanF@lpa.state.ks.us>, <security-basics@securityfocus.com>
Date: Fri, 20 Jun 2003 12:36:13 +0100

> -----Original Message-----
> From: Allan Foster [mailto:AllanF@lpa.state.ks.us]
>
> I have found EFS to be effective only as long as the encrypted
> file is on a Windows 2000/XP machine. As soon as you copy it to
> a computer with a different operating system, the file is decrypted.
>
> Allan Foster, CISA, CISSP
> Principal IS Auditor
> Legislative Post Audit

Erm, am I missing something here?

Surely a file system (in the sense it's being discussed here) is only
concerned with the local storage of data. You yourself are decrypting the
file when you copy it the other machine (or decrypting/re-encrypting if
you're copying it to another 2K/XP box with EFS).

Would you expect the particularities of a file under any given file system
to be the same if you copied the file to a differing file system? It's like
saying "I always wondered why my NTFS compressed files started taking up
more room when I copied them onto floppy disk, then off onto a FAT hard
disk." ;-p You're limited by the functionality of the file system you're
copying the file to, not the file system you're copying it from.

Are you perhaps more conversant with file crypto software (which, obviously
would stay the same regardless of OS and FS) rather than low level disk
crypto? Don't forget - EFS is intended to protect the entire hard disk from
unauthorised access - not to specifically encrypt files for safe
transmission.

Just my ?0.02,

Cheers,

Steve.

--
Stephen Wilson
Senior Security Consultant
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• Previous message: hong li: "GLBA compliance"
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