Unless you want your identity more easily stolen, it might be a good idea to remove your birth date and hometown from online profiles.

That is, according to Alessandro Acquisti and Ralph Gross, two enterprising Carnegie-Mellon University professors who say they’ve “cracked the code” used to issue Social Security numbers.

It’s pretty common knowledge that geography and birthdays play a role in determining Social Security numbers. Since many people now willingly give up their hometown and birthdays on social networking sites and in other public records, Acquisti and Gross set out to determine if the precious digits really could be predicted using publicly available information.

Turns out, they can be.

According to ABC News, the researchers studied people born after 1988, when the government began issuing numbers at birth. The researchers were able to correctly identify — in one attempt — the first five digits of the number for 44 percent of individuals. And, for 8.5 percent of those people, they got all nine digits correct in fewer than 1,000 attempts.

That means that a very simple computer program — given only a modicum of information about you — will be able to produce a relatively small number of possibilities for your Social Security number, and then input those possibilities into one of those ridiculous “instant” credit approval sites until it hits upon the correct number.

If any criminals figure out the system — and you can bet they will soon, if they haven’t already — the results could be devastating. Americans spent almost $50 billion in 2007 alone fighting identity theft, according to the ABC News article.

It’s bad enough that criminals already have no problem sifting through our trash, stealing our mail, and buying lists of names and numbers obtained through illegal means, but now they won’t even have to leave their computer to get our numbers. Any criminal with your name, birth date and Social Security number can get just about anything in your name, from a loan to a utility account.

Fortunately for those who will be born starting next year, the Social Security Administration will begin assigning the numbers randomly in 2010 — meaning that birth dates and hometowns won’t tell any more about you than your horoscope will. Kudos to the SSA for this move, but it might be too little, too late for some Americans.

Acquisti and Gross’s study will be published in today’s edition of Proceedings of the National Academy of Sciences.