Re: New release of CFS Unix encrypting file system available

In article <199510271954.PAA20647@universe.digex.net>
Scott Brickner <sjb@universe.digex.net> wrote:
>Matt Blaze writes:
>>CFS pushes encryption services into the Unix(tm) file system.  It
>>supports secure storage at the system level through a standard Unix
>>file system interface to encrypted files.  Users associate a
>>cryptographic key with the directories they wish to protect.  Files in
>>these directories (as well as their pathname components) are
>>transparently encrypted and decrypted with the specified key without
>>further user intervention; cleartext is never stored on a disk or sent
>>to a remote file server.  CFS employs a novel combination of DES
>>stream and codebook cipher modes to provide high security with good
>>performance on a modern workstation.  CFS can use any available file
>>system for its underlying storage without modification, including
>>remote file servers such as NFS.  System management functions, such as
>>file backup, work in a normal manner and without knowledge of the key.
>
>What happens to hard links?
>
>mkdir foo bar
>CFS_set_directory_key -directory ./foo -key foo-key
>CFS_set_directory_key -directory ./bar -key bar-key
>cp /etc/passwd ./foo/test1
>ln ./foo/footest ./bar/bartest
>cmp ./foo/footest ./bar/bartest

This is a serious flaw. The emperor has no clothes. People should
sue at&t for this shit.

Anonymous writes:
> >
> >What happens to hard links?
> >
> >mkdir foo bar
> >CFS_set_directory_key -directory ./foo -key foo-key
> >CFS_set_directory_key -directory ./bar -key bar-key
> >cp /etc/passwd ./foo/test1
> >ln ./foo/footest ./bar/bartest
> >cmp ./foo/footest ./bar/bartest
> 
> This is a serious flaw. The emperor has no clothes. People should
> sue at&t for this shit.

I'm not sure why I'm bothering to respond to this, but I'd hate to
think someone might take the above message seriously and think that
there's some kind of "serious flaw" in CFS demonstrated by this sequence
of (hypothetical, incorrect) commands.  So here goes:

What on earth are you talking about?

As I pointed out in a previous message, that's not how CFS works - you
can't link across encrypted directories.

There may be (and probably are) bugs in or attacks against CFS, but this
isn't one of them.

-matt

Matt Blaze enscribed thusly:
> 
> Anonymous writes:
> > >
> > >What happens to hard links?
> > >
> > >mkdir foo bar
> > >CFS_set_directory_key -directory ./foo -key foo-key
> > >CFS_set_directory_key -directory ./bar -key bar-key
> > >cp /etc/passwd ./foo/test1
> > >ln ./foo/footest ./bar/bartest
> > >cmp ./foo/footest ./bar/bartest
> > 
> > This is a serious flaw. The emperor has no clothes. People should
> > sue at&t for this shit.

	"Sue AT&T..."  For free, unsupported software?  In a remark's
from a coward hiding behind an anonymus remailer.  For a problem
that is all in his own mind!

	Give Me A Break!

> I'm not sure why I'm bothering to respond to this, but I'd hate to
> think someone might take the above message seriously and think that
> there's some kind of "serious flaw" in CFS demonstrated by this sequence
> of (hypothetical, incorrect) commands.  So here goes:

	Matt, you're responding to an annonymous twit spouting ignorant
ravings because if you didn't, some others would think this guy had something
significant to say.  It's a sad state of afairs when someone creates a
great package like CFS and then has to deal with an annoyance like this.

> What on earth are you talking about?

	You think he knows?  You give him a lot more credit than I would!

> As I pointed out in a previous message, that's not how CFS works - you
> can't link across encrypted directories.
> 
> There may be (and probably are) bugs in or attacks against CFS, but this
> isn't one of them.

	To quote one of Gary Trudeau's characters from "Doonsburry" -
"Look!  The clothes have no Empereror!"

> -matt

	Mike
-- 
 Michael H. Warfield    |  (770) 985-6132   |  mhw@WittsEnd.com
  (The Mad Wizard)      |  (770) 925-8248   |  http://www.wittsend.com/mhw/
  NIC whois:  MHW9      |  An optimist believes we live in the best of all
 PGP Key: 0xDF1DD471    |  possible worlds.  A pessimist is sure of it!

Anonymous User <nobody@c2.org> writes:

>This is a serious flaw. The emperor has no clothes. People should
>sue at&t for this shit.

This is one of those times that I don't see much use for anonymity...
-- 
` . . . I'm a sysadmin, with an admitted preference for things I can
reboot over things I have to negotiate with . . . '
		Mike Shaver (shaver@neon.ingenia.com)