I can confirm this. Attempting "/etc/init.d/cryptdisks start" at the rescue prompt during bootup also fails; it looks like it can't grab the terminal to read from. Running the same command from a terminal after the system has started works normally.
-- cryptsetup fails to read password from console at boot time https://launchpad.net/bugs/67570 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs