[clug] SSH Public key auth + Encrypted home dir

steve jenkin sjenkin at canb.auug.org.au
Tue Aug 25 15:23:53 MDT 2009

Michael Cohen wrote on 25/8/09 10:29 PM:

> I have never really understood the advantage that per user crypted
> home dir give you. It seems that the threat model is to prevent one
> user from reading another user's encrypted files, but this is normally
> enforced by system permissions. If a user is able to bypass system
> permissions (e.g. if they are root) they can easily also extract
> encryption keys when a user logs in to decrypt their home dir (or just
> copy said user's files when they log in and decrypt them). I can
> understand volume encryption as protection against a stolen laptop
> etc, but encrypting just the home dir seems to suggest you dont trust
> the system you are running on.
> Michael.


Is it to protect against super-user accessing your files?

Plus you've never said how you enter the passphrase on login, before the
home directory is mounted.

If it doesn't ask, then root can presumably 'su -' and get the files.

If you leave the directory mounted ('screen') then root will be able to
just read any file, won't they?

The only advantage it seems to give is protecting backups/files copied

Steve Jenkin, Info Tech, Systems and Design Specialist.
0412 786 915 (+61 412 786 915)
PO Box 48, Kippax ACT 2615, AUSTRALIA

sjenkin at canb.auug.org.au http://members.tip.net.au/~sjenkin

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