LAS VEGAS, Nevada (AFP) - Security specialists on Sunday showed that cracking top-rated locks said to secure the US Pentagon and Britain's royal family is child's play. Marc Tobias was in a sea of hackers practicing lock picking at a DefCon gathering in Las Vegas when he easily opened Medeco's flagship lock with a paper clip and a key cut from plastic sheets in a Shrinky Dinks toy. "We think this is a pretty serious threat, and the government guys here we've been talking to agree," Tobias told AFP.