I changed cryptsetup.functions for a friend to be able to mount several partitions which have been encrypted with the same password. It will basically try the last entered password for the "next" partition.
Tested with Ubuntu 9.04 (i386 in vbox with 2-3 encrypted logical volumes), only!
extraxt and move to /lib/cryptsetup/cryptsetup.functions-k
chmod 644 /lib/cryptsetup/cryptsetup.functions-k
chown root:root /lib/cryptsetup/cryptsetup.functions-k
in /etc/init.d/cryptdisks-early (and possibly /etc/init.d/cryptdisks, but I don't think its nessesary):
around line 20, change
if [ -r /lib/cryptsetup/cryptdisks.functions ]; then
that's it. You can always undo the changes by changing /etc/init.d/cryptdisks-early back (or copy over a backup copy).
if [ -r /lib/cryptsetup/cryptdisks.functions-k ]; then
If your system is unable to boot, you can for example use the debian live rescue cd  (includes lvm support) to undo the changes. Good luck.
Use at your own risk.