Mike Halcrow has written a paper on Installing and configuring eCryptfs with a trusted platform module (TPM) key. This paper is available on IBM Systems Information Center along with a bunch of other step-by-step guides.
This paper describes how to use a TPM key directly with eCryptfs. It demonstrates the flexibility of eCryptfs’ pluggable key module framework. Since the TPM wasn’t designed to do bulk encryption, if you actually set eCryptfs up this way, you’ll get pretty low performance, but it is an interesting exercise nonetheless and if you have small bits of information that you want strongly protected, this does provide one good option. I hear that Mike is working on replicating this experiment with a wrappered key which should provide much better performance but requires a little additional code.
In addition to showing how to integrated the TPM with eCryptfs, this paper also contains a step-by-step descriptions on how to do ancillary operations like how to enable encrypted swap in Red Hat Enterprise Linux 5.2 and how to get your TPM up and operational. This side content alone makes the paper useful.