Re: Mounting Crypted directories on Multiuser Machines.

[Jeremiah A Blatz <jer+@andrew.cmu.edu>]

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snow <snow@smoke.suba.com> writes:
<sniup description of user directories>
>        and inside each directory they have:
>  
>        /home/usr1/html/
>                  /files/
>                  /.login    
>                  /.usr1crypt
>  
>       such that /.usr1crypt gets mounted at _login_ time as a crypted file
>  system under /files.

Umm, I guess you could make mount setuid root or something. Is this
just a linux thing? But wait, there's more.  

>       Or am I missing something more basic? 

Yup.

>       It would seem that running something like this would do 2 things.
>    
>       1) It would be much more difficult to prove that a service provider 
>          knew what files a user was keeping lying around because unless
>          the user was logged in, not even the Sysadmin could "peek" at the
>          files.

There's nothing to prevent root from grabbing your password when you
log in. Root can see *everything.*

>       2) Provide the user with greater privacy. Users could keep PGP keys 
>          on the system without much risk, and as long as access was either
>          thru the console, or thru something like ssh, you should be rather
>          safe. 

If a user on the system has your password, they can edit your .login
to give them your filesystem password. If they have the root password,
well, you're screwed.

AKAIK, the only benefit od encrypted drives is that the sysadmin
cannot be forced to reveal the contents of the drive (5th amendment
and all). You could do the same thing on a multiuser system by having
one encrypted partition, and making symlinks from each user's
directory to their directy in the encrypted drive. This would be a bit
more efficient, I think.

Jer

"standing on top of the world/ never knew how you never could/ never knew
 why you never could live/ innocent life that everyone did" -Wormhole

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