Erase the LUKS keys with a special password on the unlock prompt

 Installing this package lets you configure a special "nuke password" that
 can be used to destroy the encryption keys required to unlock the encrypted
 partitions. This password can be entered in the usual early-boot prompt
 asking the passphrase to unlock the encrypted partition(s).
 .
 This provides a relatively stealth way to make your data unreadable in
 case you fear that your computer is going to be seized.
 .
 After installation, use “dpkg-reconfigure cryptsetup-nuke-password” to
 configure your nuke password.