Little Brother

I missed Harajuku Fun Madness. The company had suspended the game indefinitely. They said that for “security reasons” they didn’t think it would be a good idea to hide things and then send people off to find them. What if someone thought it was a bomb? What if someone put a bomb in the same spot?

What if I got hit by lightning while walking with an umbrella? Ban umbrellas! Fight the menace of lightning!

I kept on using my laptop, though I got a skin-crawly feeling when I used it. Whoever had wiretapped it would wonder why I didn’t use it. I figured I’d just do some random surfing with it every day, a little less each day, so that anyone watching would see me slowly changing my habits, not doing a sudden reversal. Mostly I read those creepy obits — all those thousands of my friends and neighbors dead at the bottom of the Bay.

Truth be told, I was doing less and less homework every day. I had business elsewhere. I burned new stacks of ParanoidXbox every day, fifty or sixty, and took them around the city to people I’d heard were willing to burn sixty of their own and hand them out to their friends.

I wasn’t too worried about getting caught doing this, because I had good crypto on my side. Crypto is cryptography, or “secret writing,” and it’s been around since Roman times (literally: Augustus Caesar was a big fan and liked to invent his own codes, some of which we use today for scrambling joke punchlines in email).

Crypto is math. Hard math. I’m not going to try to explain it in detail because I don’t have the math to really get my head around it, either — look it up on Wikipedia if you really want.

But here’s the Cliff’s Notes version: Some kinds of mathematical functions are really easy to do in one direction and really hard to do in the other direction. It’s easy to multiply two big prime numbers together and make a giant number. It’s really, really hard to take any given giant number and figure out which primes multiply together to give you that number.

That means that if you can come up with a way of scrambling something based on multiplying large primes, unscrambling it without knowing those primes will be hard. Wicked hard. Like, a trillion years of all the computers ever invented working 24/7 won’t be able to do it.

There are four parts to any crypto message: the original message, called the “cleartext.” The scrambled message, called the “ciphertext.” The scrambling system, called the “cipher.” And finally there’s the key: secret stuff you feed into the cipher along with the cleartext to make ciphertext.

It used to be that crypto people tried to keep all of this a secret. Every agency and government had its own ciphers and its own keys. The Nazis and the Allies didn’t want the other guys to know how they scrambled their messages, let alone the keys that they could use to descramble them. That sounds like a good idea, right?

Wrong.

The first time anyone told me about all this prime factoring stuff, I immediately said, “No way, that’s BS. I mean, sure it’s hard to do this prime factorization stuff, whatever you say it is. But it used to be impossible to fly or go to the moon or get a hard-drive with more than a few kilobytes of storage. Someone must have invented a way of descrambling the messages.” I had visions of a hollow mountain full of National Security Agency mathematicians reading every email in the world and snickering.

In fact, that’s pretty much what happened during World War II. That’s the reason that life isn’t more like Castle Wolfenstein, where I’ve spent many days hunting Nazis.

The thing is, ciphers are hard to keep secret. There’s a lot of math that goes into one, and if they’re widely used, then everyone who uses them has to keep them a secret too, and if someone changes sides, you have to find a new cipher.

The Nazi cipher was called Enigma, and they used a little mechanical computer called an Enigma Machine to scramble and unscramble the messages they got. Every sub and boat and station needed one of these, so it was inevitable that eventually the Allies would get their hands on one.

When they did, they cracked it. That work was led by my personal all-time hero, a guy named Alan Turing, who pretty much invented computers as we know them today. Unfortunately for him, he was gay, so after the war ended, the stupid British government forced him to get shot up with hormones to “cure” his homosexuality and he killed himself. Darryl gave me a biography of Turing for my 14th birthday — wrapped in twenty layers of paper and in a recycled Batmobile toy, he was like that with presents — and I’ve been a Turing junkie ever since.

Now the Allies had the Enigma Machine, and they could intercept lots of Nazi radio-messages, which shouldn’t have been that big a deal, since every captain had his own secret key. Since the Allies didn’t have the keys, having the machine shouldn’t have helped.

Here’s where secrecy hurts crypto. The Enigma cipher was flawed. Once Turing looked hard at it, he figured out that the Nazi cryptographers had made a mathematical mistake. By getting his hands on an Enigma Machine, Turing could figure out how to crack any Nazi message, no matter what key it used.

That cost the Nazis the war. I mean, don’t get me wrong. That’s good news. Take it from a Castle Wolfenstein veteran. You wouldn’t want the Nazis running the country.

After the war, cryptographers spent a lot of time thinking about this. The problem had been that Turing was smarter than the guy who thought up Enigma. Any time you had a cipher, you were vulnerable to someone smarter than you coming up with a way of breaking it.

And the more they thought about it, the more they realized that anyone can come up with a security system that he can’t figure out how to break. But no one can figure out what a smarter person might do.

You have to publish a cipher to know that it works. You have to tell as many people as possible how it works, so that they can thwack on it with everything they have, testing its security. The longer you go without anyone finding a flaw, the more secure you are.

Which is how it stands today. If you want to be safe, you don’t use crypto that some genius thought of last week. You use the stuff that people have been using for as long as possible without anyone figuring out how to break them. Whether you’re a bank, a terrorist, a government or a teenager, you use the same ciphers.

If you tried to use your own cipher, there’d be the chance that someone out there had found a flaw you missed and was doing a Turing on your butt, deciphering all your “secret” messages and chuckling at your dumb gossip, financial transactions and military secrets.

So I knew that crypto would keep me safe from eavesdroppers, but I wasn’t ready to deal with histograms.