[vox-tech] Encrypted CDROM

[Richard Harke]

On Wed August 3 2005 22:50, Michael Wenk wrote:
> On Wednesday 03 August 2005 16:51, Richard Harke wrote:
> > On Wed August 3 2005 13:03, Michael J Wenk wrote:
> > > On Wed, Aug 03, 2005 at 12:44:52PM -0700, Richard Harke wrote:
> > > > Using loopback and cryptsetup (which uses the device mapper)
> > > > I created an encrypted file system about the size of a CDRom. I put
> > > > some files into this file system then I burned a CD using cdrecord.
> > > > No error indications so far. Now I want to read the CD to verify
> > > > whats on it. When I do a cryptsetup, I get an error. The command is
> > > >
> > > > cryptsetup create --size=1431552 aname /dev/cdrom
> > > >
> > > > The error I get is Invalid argument to an ioctl call. The ioctl call
> > > > is trying to load the table to the mapper device. I ran strace but
> > > > didn't get any more info. I've looked at the source but so far
> > > > I haven't figured it out.
> > > >
> > > > Does any one out there have any ideas?
> > > >
> > > > Richard Harke
> > > > _______________________________________________
> > >
> > > All I have is a possible workaround.
> > >
> > > dd if=/dev/cdrom of=tmp.iso bs=64k
> > >
> > >
> > > Then run the cryptsetup on the iso file.
> > >
> > > More than likely(this is just a stab btw, I am not completely sure of
> > > what I am talking about and I am going off of memory of how the ioctl's
> > > interface with the driver on linux) what's happening is the ioctl
> > > called by the command is not valid with the device in question.  If you
> > > make the device into a file and then try it with the file, it *may*
> > > work.
> > >
> > > Mike
> >
> > That does work. I used dd, then losetup, cryptsetup and finally mount.
> > I need to use losetup first because cryptsetup works on a device,
> > not a file. As long as I have lots of hard disk space, I guess I could
> > just keep the encrypted file-system images on the hard drive and just
> > write to CD for backup.
> >
> > I'm still a little curious though as I know the ioctl was to the just
> > created device-mapper device and it certainly needs a table load to
> > function.
> >
> > Richard
>
> What type of device did you use to create the filesystem in the first
> place?
>
> Mike
I created the file with:
dd if=/dev/urandom of=cdimage bs=1048576 count=699
Then I looped it back with:
losetup /dev/loop0 cdimage
Set up crypto using device mapper with:
cryptsetup create name /dev/loop0
Then make a filesystem:
mkfs -t ext3 /dev/device-mapper/name
and last mount it:
mount -t ext3 /dev/device-mapper/name /mnt

Richard