# Hey, buddy, can you spare some cycles?

From Netly News Writer Stan Gunn

How much do you really use your computer? Oh sure, you might spend eight hours a day pecking away at the Great American Novel. Maybe you work 60-hour weeks preparing budget reports. You may even be a member of some hotshot Quake clan, fragging your enemies every night. Point is, though, for the majority of the time, your computer, a device that represents more processing power than existed on the planet 30 years ago, is being wasted. Not to invoke the Puritan work ethic, but do you realize your computer is spending the greater part of its day drawing 3-D pipes to provide you with screensaver eye candy?

Why not harness that extra power for the greater good? Why not use it to search for intelligent life on other planets?

Before we get to the voices from outer space, let's talk about Mersenne primes for a minute. Bear with me. Like other primes, a Mersenne prime number can be divided only by itself and by 1. What makes a Mersenne prime special is its structure -- Mersenne primes all follow the format 2^x-1. What makes them even more special is that there are only 36 of them known, and before August 24, 1997, there were just 35. Gordon Spence found the current world record, the longest Mersenne prime ever found: 2^2976221-1 -- that's 895,932 digits if you write it out.

So what? A few days on a Cray and you could probably find a new one too. Except that Spence didn't find it on a Cray, he used a 100Mhz Pentium. Spence is one of the 2,000 members of the Great Internet Mersenne Prime Search (GIMPS). According to the GIMPS press release, it would have taken Spence on his own more than 940 years for his computer to find this prime number. But by throwing the PC power of all the members of GIMPS at the problem, two new Mersenne primes have been discovered in the last 10 months (number 35 was found in November 1996, also by the GIMPS team). So who makes up GIMPS? Volunteers, people just like you and me, except maybe a little more interested in mathematics.

GIMPS is just one of many projects that uses the idea of distributed computing, breaking up a problem into manageable chunks and handing out pieces over the Internet. Of course, not all distributed computing projects are as purely intellectual as GIMPS. Two groups are currently working to win one of RSA's secret-key encryption contests by harnessing the power of volunteers recruited on the Internet. If the Finland-based RC5 Project organizers win, they plan to split RSA's \$10,000 reward with the user who manages to break the key. The Bovine RC5 Project will give \$1,000 to the lucky person or group who finds the number, keep \$1,000 to cover its own expenses, and donate the other \$8,000 to Project Gutenberg.

Adam Beberg, currently pursuing his master's in computer science at the Illinois Institute of Technology, writes the client software that makes Bovine work. He finds that project participants have different motivations. "Well, there's lots of crypto people who are doing it for fun or to show the weaknesses of 56-bit encryption," he says. "Then you have the folks who are interested in distributed computing and operating systems. For a lot of the people who participate it's a team competition thing. Our servers rank each team by how many keys they've done each day and in total, so you can always see your rankings against everyone else. Finally, a lot of people just do it out of curiosity." There must be a lot of curiosity -- Beberg estimates that the computing power being aimed at the Bovine RC5 effort daily is equivalent to about 10,000 200Mhz Pentium Pro PCs.

One of Bovine's volunteers, who asked to remain nameless since he's running the RC5 cracking client on several of his company's servers, expresses a different purpose. "It reminds me of the old days of the Internet, before banner ads and spam," he says. "I hope I don't win, it would cause too many problems at work. I just like the idea of participating in this big group effort, accomplishing something none of us could do alone."

But let's get back to the aliens.

If you wouldn't know a Mersenne prime from a prime rib and could care less about breaking the latest cryptography algorithm, you can still find a worthy cause for your PC's idle moments. SETI@home, scheduled to start in the spring of 1998, will look like a screensaver as it runs on your PC. In the background, however, it will be downloading and analyzing data recorded at the radio telescope at Arecibo, Puerto Rico, and searching for meaningful bleeps and clicks from outer space. Big Science plans SETI@home as a two-year project, whose aim is to do real science. The chief scientist, Dr. Dan Werthimer, has been involved in SETI projects for the last 17 years and designed some of the hardware that will be used to capture the data.

David Gedye, the project director for SETI@home, hopes that thousands or even hundreds of thousands of people will be willing to run the software. He summed up the project this way: "Most people are interested in the Big Questions. There may never be a general consensus on whether there is a God, and what He or She is like, but nearly as mind-boggling as the religious questions are the ones like 'Are we alone?' With this project we have at least some chance of answering that one."

And that's what distributed computing is all about -- answering the big questions and winning bragging rights to having answered them first. It's the same competitive volunteer spirit that started the Internet and the reason that Beberg wants the RC5 winnings to go to Project Gutenberg. "It's because of what they do," he said. "They digitize books and give them away for free. I like that."

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