After changing harddrives I needed to transfer some files from the old harddrive which had an encrypted home directory. The command

did not work:

http://askubuntu.com/a/36783 pointed me in the right direction. First mount the old hard drive in the new Ubuntu installation. Then run

to add the corresponding passphrase (32 digits). Remember the second sig and mount your directory with

You will need to answer some questions. The suggested default works except for the following two questions:

and

In my case some warnings were shown saying that encryption may not have worked properly and if mounting should continue. Despite those warnings all files were accessible.