Little Brother, Cory Doctorow [thriller novels to read .TXT] 📗

plain old banking and e-commerce and other encrypted communication. You couldn't find out who was tying the Xnet, let alone who was using the Xnet.

But what about Dad's "Bayesian statistics?" I'd played with Bayesian math before. Darryl and I once tried to write our own better spam filter and when you filter spam, you need Bayesian math. Thomas Bayes was an 18th century British mathematician that no one cared about until a couple hundred years after he died, when computer scientists realized that his technique for statistically analyzing mountains of data would be super-useful for the modern world's info-Himalayas.

Here's some of how Bayesian stats work. Say you've got a bunch of spam. You take every word that's in the spam and count how many times it appears. This is called a "word frequency histogram" and it tells you what the probability is that any bag of words is likely to be spam. Now, take a ton of email that's not spam -- in the biz, they call that "ham" -- and do the same.

Wait until a new email arrives and count the words that appear in it. Then use the word-frequency histogram in the candidate message to calculate the probability that it belongs in the "spam" pile or the "ham" pile. If it turns out to be spam, you adjust the "spam" histogram accordingly. There are lots of ways to refine the technique -- looking at words in pairs, throwing away old data -- but this is how it works at core. It's one of those great, simple ideas that seems obvious after you hear about it.

It's got lots of applications -- you can ask a computer to count the lines in a picture and see if it's more like a "dog" line-frequency histogram or a "cat" line-frequency histogram. It can find porn, bank fraud, and flamewars. Useful stuff.

And it was bad news for the Xnet. Say you had the whole Internet wiretapped -- which, of course, the DHS has. You can't tell who's passing Xnet packets by looking at the contents of those packets, thanks to crypto.

What you can

do is find out who is sending way, way more encrypted traffic out than everyone else. For a normal Internet surfer, a session online is probably about 95 percent cleartext, five percent ciphertext. If someone is sending out 95 percent ciphertext, maybe you could dispatch the computer-savvy equivalents of Booger and Zit to ask them if they're terrorist drug-dealer Xnet users.

This happens all the time in China. Some smart dissident will get the idea of getting around the Great Firewall of China, which is used to censor the whole country's Internet connection, by using an encrypted connection to a computer in some other country. Now, the Party there can't tell what the dissident is surfing: maybe it's porn, or bomb-making instructions, or dirty letters from his girlfriend in the Philippines, or political material, or good news about Scientology. They don't have to know. All they have to know is that this guy gets way more encrypted traffic than his neighbors. At that point, they send him to a forced labor camp just to set an example so that everyone can see what happens to smart-asses.

So far, I was willing to bet that the Xnet was under the DHS's radar, but it wouldn't be the case forever. And after tonight, I wasn't sure that I was in any better shape than a Chinese dissident. I was putting all the people who signed onto the Xnet in jeopardy. The law didn't care if you were actually doing anything bad; they were willing to put you under the microscope just for being statistically abnormal. And I couldn't even stop it -- now that the Xnet was running, it had a life of its own.

I was going to have to fix it some other way.

I wished I could talk to Jolu about this. He worked at an Internet Service Provider called Pigspleen Net that had hired him when he was twelve, and he knew way more about the net than I did. If anyone knew how to keep our butts out of jail, it would be him.

Luckily, Van and Jolu and I were planning to meet for coffee the next night at our favorite place in the Mission after school. Officially, it was our weekly Harajuku Fun Madness team meeting, but with the game canceled and Darryl gone, it was pretty much just a weekly weep-fest, supplemented by about six phone-calls and IMs a day that went, "Are you OK? Did it really happen?" It would be good to have something else to talk about.


"You're out of your mind," Vanessa said. "Are you actually, totally, really, for-real crazy or what?"

She had shown up in her girl's school uniform because she'd been stuck going the long way home, all the way down to the San Mateo bridge then back up into the city, on a shuttle-bus service that her school was operating. She hated being seen in public in her gear, which was totally Sailor Moon -- a pleated skirt and a tunic and knee-socks. She'd been in a bad mood ever since she turned up at the cafe, which was full of older, cooler, mopey emo art students who snickered into their lattes when she turned up.

"What do you want me to do, Van?" I said. I was getting exasperated myself. School was unbearable now that the game wasn't on, now that Darryl was missing. All day long, in my classes, I consoled myself with the thought of seeing my team, what was left of it. Now we were fighting.

"I want you to stop putting yourself at risk, M1k3y." The hairs on the back of my neck stood up. Sure, we always used our team handles at team meetings, but now that my handle was also associated with my Xnet use, it scared me to hear it said aloud in a public place.

"Don't use that name in public anymore," I snapped.

Van shook her head. "That's just what I'm taking about. You could end up going to jail for this, Marcus, and not just you. Lots of people. After what happened to Darryl --"

"I'm doing this for Darryl!" Art students swiveled to look at us and I lowered my voice. "I'm doing this because the alternative is to let them get away with it all."

"You think you're going to stop them? You're out of your mind. They're the government."

"It's still our country," I said. "We still have the right to do this."

Van looked like she was going to cry. She took a couple of deep breaths and stood up. "I can't do it, I'm sorry. I can't watch you do this. It's like watching a car-wreck in slow motion. You're going to destroy yourself, and I love you too much to watch it happen."

She bent down and gave me a fierce hug and a hard kiss on the cheek that caught the edge of my mouth. "Take care of yourself, Marcus," she said. My mouth burned where her lips had pressed it. She gave Jolu the same treatment, but square on the cheek. Then she left.

Jolu and I stared at each other after she'd gone.

I put my face in my hands. "Dammit," I said, finally.

Jolu patted me on the back and ordered me another latte. "It'll be OK," he said.

"You'd think Van, of all people, would understand." Half of Van's family lived in North Korea. Her parents never forgot that they had all those people living under a crazy dictator, not able to escape to America, the way her parents had.

Jolu shrugged. "Maybe that's why she's so freaked out. Because she knows how dangerous it can get."

I knew what he was talking about. Two of Van's uncles had gone to jail and had never reappeared.

"Yeah," I said.

"So how come you weren't on Xnet last night?"

I was grateful for the distraction. I explained it all to him, the Bayesian stuff and my fear that we couldn't go on using Xnet the way we had been without getting nabbed. He listened thoughtfully.

"I see what you're saying. The problem is that if there's too much crypto in someone's Internet connection, they'll stand out as unusual. But if you don't encrypt, you'll make it easy for the bad guys to wiretap you."

"Yeah," I said. "I've been trying to figure it out all day. Maybe we could slow the connection down, spread it out over more peoples' accounts --"

"Won't work," he said. "To get it slow enough to vanish into the noise, you'd have to basically shut down the network, which isn't an option."

"You're right," I said. "But what else can we do?"

"What if we changed the definition of normal?"

And that was why Jolu got hired to work at Pigspleen when he was 12. Give him a problem with two bad solutions and he'd figure out a third totally different solution based on throwing away all your assumptions. I nodded vigorously. "Go on, tell me."

"What if the average San Francisco Internet user had a lot

more crypto in his average day on the Internet? If we could change the split so it's more like fifty-fifty cleartext to ciphertext, then the users that supply the Xnet would just look like normal."

"But how do we do that? People just don't care enough about their privacy to surf the net through an encrypted link. They don't see why it matters if eavesdroppers know what they're googling for."

"Yeah, but web-pages are small amounts of traffic. If we got people to routinely download a few giant encrypted files every day, that would create as much ciphertext as thousands of web-pages."

"You're talking about indienet," I said.

"You got it," he said.

indienet -- all lower case, always -- was the thing that made Pigspleen Net into one of the most successful independent ISPs in the world. Back when the major record labels started suing their fans for downloading their music, a lot of the independent labels and their artists were aghast. How can you make money by suing your customers?

Pigspleen's founder had the answer: she opened up a deal for any act that wanted to work with their fans instead of fighting them. Give Pigspleen a license to distribute your music to its customers and it would give you a share of the subscription fees based on how popular your music was. For an indie artist, the big problem isn't piracy, it's obscurity: no one even cares enough about your tunes to steal 'em.

It worked. Hundreds of independent acts and labels signed up with Pigspleen, and the more music there was, the more fans switched to getting their Internet service from Pigspleen, and the more money there was for the artists. Inside of a year, the ISP had a hundred thousand new customers and now it had a million -- more than half the broadband connections in the city.

"An overhaul of the indienet code has been on my plate for months now," Jolu said. "The original programs were written really fast and dirty and they could be made a lot more efficient with a little work. But I just haven't had the time. One of the high-marked to-do items has been to encrypt the connections, just because Trudy likes it that way." Trudy Doo was the founder of Pigspleen. She was an old time San Francisco punk legend, the singer/front-woman of the anarcho-feminist band Speedwhores,