partman and encrypted partitions?

[Stephen Quinney <stephen@jadevine.org.uk>]

I hope this is the correct place to be asking about how to use partman
in the debian installer. I've recently started looking into using a
custom recipe to configure the partition layout on my machines. I've
got it all working nicely with LVM and I am now wondering if it is
possible to configure selected partitions (e.g. /tmp and swap) to be
encrypted with a random key at boot time? I don't want full disk
encryption in this case which I know is supported. I've spent quite a
bit of time looking at this and it seems like maybe it is possible but
I'm struggling to find a complete example I can follow. Can anyone
help with advice or a recipe I can learn from?

Thanks,

Stephen Quinney