Full Disk Encryption with LUKS: auto mount second volume

TrueCrypt on Windows can auto mount volumes that use the same passphrase as the boot volume. You enter the passphrase only once. Is there a way to do this with LUKS?

Background: I'm currently migrating from Windows to Ubuntu. I set up Ubuntu 11.10 with LUKS full disk encryption. I use a second hard drive that is still a TrueCrypt NTFS volume. I want to change that.

You can use the decrypt_keyctl keyscript to securely cache the passphrase when mounting multiple encrypted volumes. The README describes how to do this on boot; there are some caveats with workarounds described in bug 1022815.

This should allow auto mounting of multiple encrypted volumes at boot with only one passphrase prompt. The same keyctl mechanism could be used to arrange the automounting of other volumes after boot time, but I'm not aware of a full solution.