Breaking into a lock without being noticed no longer means having to actually have the key ahead of time in order to make a copy. Computer geniuses at UC San Diego have written a computer program that can copy a key based solely on a photograph of it.

The theory is really quite simple: If a photo of a key can be captured with enough detail, the image can be translated into a numeric code that can then be used to recreate the key. Software allows for accounting for whatever angle the photo is shot at.

The spy needn't be up close and personal in order to snap the photo, either. The research shows that a photo shot with a telephoto lens from 200 feet away can offer high enough detail in order to create a copy.

One of the goals of the research is to encourage people to protect their keys in the same manner they would a credit card -- by not leaving them out in the open and not allowing them to be photographed. (The researchers note that people take great pains to blur out credit card numbers whenever they're visible, but that you'll find numerous photos of people's keys on photo sharing sites like Flickr. Voting machine company Diebold got caught up in just such an embarassing scenario early last year when it put photos of the master keys used for its machine on its website.)

Practically speaking, there's probably little worry that a common thief will attempt to burglarize you by taking a picture of your keys and then having a copy made, considering the far simpler and lower-tech alternatives available -- stealing the key, picking the lock, drilling it, or simply breaking a window next to the door and climbing in that way. But it is food for thought: What we had previously taken for granted -- that keys must be physically present in order to be copied -- is actually completely wrong.