Fedora :: Getting Console Input During System Startup?

I am setting up a system for students to use to run lab-based exams. On bootup, the system needs to download an encrypted file containing the exam files, and then ask for a decryption password.

I want to do this during system startup (before anyone logs in). But I am having trouble getting keyboard input at this point.

I've put a script in /etc/rc.d/rc5.d/S99examsetup along the following lines:

Code:
#!/bin/bash
echo -n "Enter password:"
read EXAMPW
echo "You gave me: $EXAMPW"

but it doesn't respond to keyboard input. I have tried appending "< /dev/console" but this also doesn't work; in fact if I insert 'tty' before the first 'echo', it tells me that /dev/console is the tty being used for input anyway.

Is there a way round this? I can use plymouth ask-for-password, but that doesn't seem very portable, and it interacts badly with the graphics driver on one of my machines.