New security measure idea:

Write a computer virus and infect your own system. Write it so it infects all the files on your system but otherwise identifies your own system and does no harm lying dormant.

If anyone hacks your system and downloads a file it will activate the virus and infect the attackers system and destroy it.

No not serious but the idea made me smile.

@freemo If the police would do this it would be entrapment or something.