Hi!
> > Now that laptop is stolen at an airport. The thief decides
> > to try to improve his take by grabbing useful information
> > from documents. The encrypted documents are untouchable,
> > of course. It _doesn't matter_ that the thief has the
> > hardware, the decryption key is protected by a passphrase
> > which is _nowhere_ on the hard drive.
> >
> > The only place that sensitive, unencrypted data could be
> > on such a machine is in swap. In fact, it is _likely_ to
> > be in swap.
> >
> > Encrypted swap solves this _particular_ problem nicely,
> > does it not?
>
> You got it bit.. wrong. Or, non-specific. If you assume that your laptop
> is stolen while its powered, then encrypted swap won't help you (strings
> /proc/kcore & the likes). If its going to be stolen while its offline, you
> can have your shutdown scripts blank the swap partition and the boot
> scripts call mkswap on it.
>
> Or, somehow better & safer (or, explain the drawback):
>
> spiral:~# dd if=/dev/zero of=/swap bs=1024k count=16
> 16+0 records in
> 16+0 records out
> spiral:~# losetup -e DES /dev/loop0 /swap
> Password:
> Init (up to 16 hex digits):
> spiral:~# mkswap /dev/loop0
> Setting up swapspace version 1, size = 16773120 bytes
> spiral:~# swapon /dev/loop0
> spiral:~# cat /proc/swaps
> Filename Type Size Used Priority
> /dev/loop0 partition 16376 0 -3
>
> There, you have the swap encrypted, up and running. Of course, if
> you need
You have your swap encrypted, but I'm not sure for how long you'll see
it running before it deadlocks. Unless -e DES and loop were designed
for use with swap (were they?), this is tricky. Does anyone know if
swapping over loop is safe?
> more fancy encryption than the default, XOR or DES, get the crypto patch.
> You only need to have a script that does the stuff, that runs when the
> system boots, without shutdown scripts (in case of power/battery failure
> these might not be executed, hence the swap would not be wiped). Of
> course, you'll need to enter the losetup password upon booting, which
> might prove annoying (then again, if kernel would provide swap
> encryption, the only way to make it non-decryptable would be for you to
> enter a password, same drawback actually).
You could generate random password each boot. Should work well enough.
Pavel
-- I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care." Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Tue Aug 07 2001 - 21:00:48 EST