2006/11/17, Andreas Jaeger <aj@suse.de>:

FYI, here're the minutes from our discussion.  I hope to see this for
10.3...

Andreas

Topic: Encrypted Home Directories

* Main new feature: Per user encrypted home

* Proposal:
  - Enable per user encrypted home partitions (using pam_mount)
  - use dm-crypt + LUKS as default instead of cryptoloop

Challenges + Problems:

* currently KDM accesses home directory before authentification (after
  user name is known) to get information about the last session.  An
  encrypted home partition this needs changes in the logic.

* For ssh-key it's a problem to read the key files since they are
  stored in the home directory, only password authentification would
  work.

* Other programs might read the homedirectory, like procmail.  We have
  to check which other programs do this and decide how to handle this,
  e.g. a shadow home directory (or union filesystems) for procmail,
  secret keys...

* Backup software is a challenge, users want encrypted backups.

* Manually mounting via /etc/fstab is not possible currently with
  dm-crypt, other distributions use /etc/fscrypttab or we would need
  to extra add support to allow this with /etc/fstab.

  Use-case: A separate encrypted partition with secrect data that is
  only mounted manually if needed by the user and then unmounted
  again.

* On-the-fly upgrade would be fine.  Unfortunately dm-crypt uses two
  extra blocks so this cannot be done without losing data.

* 10.2 has all the basic support for dm-crypt and LUKS but it's not
  integrated.

* Linux only supports only 255 loopback mounts, so this limits the
  maximum of users that can be logged in at the same time.

* FUSE and encrypted single files would be an option as well but there
  are some drawbacks with it.

* Use case: Laptop stolen or taken away.  If one user is comprimised,
  not all should be comprised.

* Masterkey that is encrypted by the users login, so that only one
  password is needed to login.

* screensaver issues (just close the lid)
  What happens with a locked screen and laptop taken away still running?

* suspend to disk
  How to handle suspend to disk? Umount before suspend and remount later?

Changes for this:

YaST changes:
* support dm-crypt by default for new installations in yast2-storage
* during user creation allow creation of encrypted home directories
* During update: Support old cryptoloop partitions and allow new
  installations.

Base system changes:
* Using pam_mount
* Enable dm-crypt in boot.crypto
* Handle /etc/fstab unless to not regress
* Migration programs to migrate from cryptoloop to dm-crypt

Andreas
--
Andreas Jaeger, aj@suse.de, http://www.suse.de/~aj/
  SUSE Linux Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
   GPG fingerprint = 93A3 365E CE47 B889 DF7F  FED1 389A 563C C272 A126