It's not much of a spoiler to say the aliens in District 9 have the snazziest trigger lock around. The Prawns, as they are known in the movie, have some strange ideas for safety, though. Their trigger lock is DNA-encoded not to keep little Prawns away from dangerous gear, but to prevent any other species from activating the weapons. (That's the sort of detail that raises all sorts of questions about just who the Prawns were fighting that they needed this kind of security, and whether the enemy also had DNA-locked rifles.)
While the Prawns seem to have mastered DNA-detecting technology, it remains a bit beyond our reach out here in the real, human world. But that may be the next big frontier in biometrics. Because, let's face it, the typical kinds of biometric security used in of the lairs of movie super-villains isn't science-fiction anymore—it's reality.
Fingerprint scan? We can do that on a laptop, or even a mere thumb drive. Palm scan? Pssh. Placing a hand on the scanner is passé. Retinal scan? Of course. Facial recognition? Voice recognition? Done and done. All of these different biometrics has been exploited by security companies trying to make money in a world where verifying authenticity is becoming an increasing problem. But the biological signature big business and national governments really want to capture is DNA. Unlike our faces and voices, it never changes. Unlike our fingerprints, it's very difficult to fake. And except for identical twins, it's totally unique to each individual (and it may soon be possible to distinguish even identical twins [pdf]). Because this technology would be so valuable, everyone from the Austrian national government to major corporations is toiling away (pdf) in their R&D departments to develop a DNA biometric lock.
But fear not, defenders of privacy: Science is still reasonably far (pdf) from using DNA for a biometric lock. First, there's the sampling problem. There was a time when the only way to get a useful DNA sample was to get a drop of blood or a swab of tissue from inside the person's mouth. And while it would probably be fair to force Tom Cruise to prick his finger every time he wanted to gain entry to the Mindhead—err, the Scientology—err, his secret hideaway, useful DNA can be extracted from skin cells just by using a simple adhesive piece of paper. Still, not optimal for a lock and key device.
Then the DNA has to be amplified and sequenced. It's a staple of Hollywood crime shows that DNA this process can be accomplished in a matter of minutes, but in reality it takes hours to run the polymerase chain reaction. Then the amplified DNA has to be sequenced, and only then can it be matched up to an encoded "lock" to see if the person can be admitted. Again, watching Tom Cruise stand fuming for three hours outside the fortress of solitude is a pleasing thought, but it's not really going to happen.
Still, there are a number of other DNA-oriented tricks companies are trying. Applied DNA Sciences, a company in Stony Brook, NY, has discovered a way to layer plant DNA into one-of-a-kind objects, like art work, or antiques, that they swear will have no effect on the object. They also can layer the DNA into ink and toner, allowing the possibility of printing money or credit cards with a DNA signature that could be read with a special scanner.
Of course, the fast way to figure this stuff out would be to reverse-engineer some handy alien weapons and see just what makes the weapons work or not work. Did the human scientists in District 9 think of that? Well, that would be a spoiler, now wouldn't it?