Comment 1 for bug 1320486

xlockmore is dead upstream and was removed from the Debian repositories in 2012. There hasn't been a version in the 'buntu repositories since Quantal (12.10). xlockmore 1:5.31-1.1 was dropped from Debian testing because it was left in a buggy, unmaintained state with obvious security flaws. Since the package isn't meant to exist in the 'buntu repositories, this isn't a bug and is being closed as such. Thank you for taking the time to file a report.

Refer to:
http://packages.qa.debian.org/x/xlockmore.html
https://launchpad.net/ubuntu/+source/xlockmore