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I would like to have a directory accessible to a couple of users, and not readable by maintenance types ... I can do what I want using ecryptfs and a password known only to the "couple of users" in question, who then can mount the directory and use as they see fit.

I would love to be able to automate that process and unlock the directory at login - again, only for the "couple users" in question, without asking a password.

Gnome-keyring is able to store passphrases/passwords encrypted; and, apparently, if I could get a key identity to ecryptfs, Gnome PAM modules would allow the key with that identity to be unlocked, and the directory could be mounted.

Alas, I have found no way to go from point A (Gnome PAM keyring module) to point B (use the unlocked key in ecryptfs).

Another use of the same mechanism would allow to build a "key escrow" mechanism, where keys to encrypted volumes are safekept with, e.g., HR; so that company information in encrypted directories can be recovered if you pass under the proverbial bus.

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Another solution are gpg-encryption. You can eckrypt a directory using gpg and peoples public gpg-keys and then publish the directory thru UbuntuOne to each of the participants.

A convenient tool for Nautilus to do this comes with seahorse-plugins (just right-click in the file dialog).

Right know there is a problem with the package seahorse-plugins (11.10), but there is a PPA ppa:mdeslaur/testing with a funktioning package.

A directory encrypted using gpg can function as a key escrow, its possible to store this directory in public, store it in a third part deposit, distribute it on a public network, and only those that the directory where encrypted for can read.

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This appears veerrry promising, as it's the only solution I've seen that would pass the key escrow capability test. I suppose that I wouldn't even need to use UbuntuOne if the participants can login to the machine where this encrypted directory resides. Thanks! – Michel Dec 2 '11 at 0:59

Create a new user on a server accessible with ssh (openssh-server installed) and encrypted home directory. You can then add all peoples ssh-keys letting each user use the command ssh-copy from their client using a "public" known password. When this is done change the password. All users that copied their public ssh-keys can still login with their password for the ssh-key not knowing your secret password for the account. If you want to retire one of the users just remove the public-key from ~/.ssh/authorized_keys.

You can also manually add users public keys to ~/.ssh/autorized_keys

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Thanks, but there is a something I don't get: Yes, they will be able to login. But where will the ecryptfs password come from? If one logs in normally, it comed from pam (use_first_pass); but here ? – Michel Dec 2 '11 at 0:56

For the key escrow aspect of your question, see, which is designed specifically for eCryptfs key escrow.

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