NOAH ADAMS, host:

From NPR News, this DAY TO DAY. A message from World War II encoded by the infamous Nazi Enigma machine has finally been cracked. It's one of three such messages left over from the war that has never been read until now. The code-breaking was pulled off by a vast team of computers working together by way of the Internet. And here to tell us how this was done is Ira Flatow, host of Science Friday, a regular Thursday contributor to DAY TO DAY.

First of all, what, Ira, does the message say?

IRA FLATOW reporting:

Well, it apparently was just a very simple short message sent by a submarine describing how it had been forced to submerge during a battle in 1942 in the North Atlantic, and it merely states its position and a little bit of the weather data that it collected.

ADAMS: Now, how was the code broken, this code that has been unbroken since the war?

FLATOW: Well, it's actually quite interesting. This was broken by something called the M4 Project, and what's really interesting about this project is that it's open to all of us, Noah, to participate. You remember the SETI Project, the search for life in outer space?

ADAMS: This is one where it would hook up computers at home, sometimes even at night when you're sleeping?

FLATOW: Exactly. Well, this one mimics that kind of distributed computing, as its called.

ADAMS: It just creates a giant supercomputer?

FLATOW: Exactly, all over the Web.

ADAMS: Now, take us back a bit, and remind us how the Enigma code machine worked.

FLATOW: Yeah, it sort of looked like that old-fashion manual Remington typewriter, I know, Noah, that you still have under your desk, but this one had a set of rotors, and you would set the rotors to map all the letters in the alphabet. You could use three rotors. You could use more rotors. The more rotors you used, the tougher the code was, and this code was made using four rotors, and the Germans thought that this was code was so difficult to crack by using all those rotors that it basically indecipherable.

Well, the British set up a decoding center at Blechley Park in England and actually created some of the world's first computers, these room-sized, super-secret, glowing, vacuum-tubed jobs, you know, in the 1940s, and they hired top computer minds to decode the Enigma and other Nazi codes. What they were trying to do was to figure out how the original rotors were set up on the Enigma machine that made the code.

So if they could figure out how those rotors were set up, they could mimic the machine, and with a little bit of luck, having German encoders slip up every once in a while, they were actually successful in breaking some of these codes.

ADAMS: Now, can you still get in on the project to go after what's on the other two messages?

FLATOW: Absolutely, you can download a little bit of software and run it on your PC or Linux machine. Unfortunately, Mac folks are out in the cold again, unless they know how to compile a computer on their Linux machine. And they basically use a brute force method. They're going to try to use all the rotor settings and then try to use all the electronic settings and hopefully together everybody will be able to break all the codes.

ADAMS: And why?

FLATOW: Noah, why do hackers do anything? I think it's just to show that this can be done. I mean there's no reason to decode a submarine position in the North Atlantic. After all, you know, why do computer geeks do anything if not for the challenge, and I think, Noah, if you have to ask, you just don't belong here.

ADAMS: Ira Flatow, host of Science Friday, regular Thursday contributor too, DAY TO DAY. Thank you, Ira.

FLATOW: You're welcome.

ADAMS: And a bit of a caveat here. To avoid any security problems with the computer, if you want to take part safely in the M4 project, be sure to customize your username and your password. Transcript provided by NPR, Copyright NPR.