You can type control codes (except for NUL, DEL, CR, LF?) on the Linux console by pressing Ctrl+letter. Might add some security to your disk encryption password, unless you need to enter it from a GUI :)
How do you write DEL, which Ctrl+key is that? I had written this actually as ^H^@^@^A, but realized that ^H may remove characters but is not DEL, so I edited that out of my previous comment.
Yes, I don't know if there is any key combination to type DEL. Ctrl just clears bit 6. ^S and ^Q are also problematic because of XON/XOFF. I did use ^G (BEEP!) in a password once.
edit ^H is also swallowed by the line editor of course.