Marc Weber Tobias is a lock breaker. It's what he does for a living, the way he makes some of his money and much of his name. But for a guy like Tobias, it's far more than a job.

Hacking locks, when you pick your targets, can be a sort of geek revenge-as-hobby, an adolescent life view morphing into a dangerous adult obsession. And like addiction, obsession doesn't need provocation. It needs an excuse.

Tobias' excuse, the way he remembers it, was that he was pissed off at Japan — the country, in general — because the 50th anniversary of Pearl Harbor had come and gone without a formal apology from the Japanese government. He was also aware that one of Japan's more prominent lock companies, Showa, was making significant inroads into the US hotel lock market. So therefore Showa, Tobias reasoned, was a legitimate target. Never mind that the brand name for a magnetic hotel lock has no more relationship to the reign of Emperor Hirohito or the bombing of the US Pacific fleet than Alamo Rent A Car has to the bloodline of Davy Crockett — Marc had decided to take it personally, and ensure that, for Showa at least, December 7, 1994, would be a day that would live on in infamy.

He drove from his frozen home in South Dakota to the warm sands of Southwestern Florida and checked into a hotel equipped with Showa locks. His plan was to right this historic wrong — to activate his superpower, Hulk out, and smash their puny company. But first, of course, his inner Bruce Banner had to learn how to hack the Showa lock.

The hotel lock Showa made at the time was a variant of the familiar type you'd find outside most modern hotel rooms, the kind where a credit card-shaped key slides into a slot. The design was simple, elegant, and straight-forward, and solved a specific problem.

For generations, hotels had suffered from the problem of lost or stolen room keys. Replacing the keys not only cost hotels money and time, but also opened them up to all sorts of liability — at any given moment, they had no idea how many people out there had keys to the rooms of their sleeping guests. Unless they replaced each lock after each guest, a hotel could be on the hook for hundreds of potential home invasions.

The Showa credit card-style keys solved the key-loss problem. Unlike physical keys, they were programmable and reprogrammable — and inscrutable, too, because you couldn't just take them to a hardware store and make a copy.

The reason was magnets. Each of the credit card-like keys was imprinted with a unique fingerprint of small, round magnets, each with a north (or positive) or south (or negative) polarity. These magnets, N or S, were arranged across the card like dots on a domino. Each domino configuration represented a unique key code.

Each room lock had its own unique arrangements of dots. A lock's magnet pattern was exactly the same arrangement as the one on its corresponding credit card key, but with the opposite polarity, like a photograph and its negative. Slide the right key into the right lock and the magnetic spots in the lock would pair up with the magnetic spots on the card; you'd get a green light, and click — the door would open.

With this system, you didn't have to shell out to a locksmith every time you lost a key. Instead, you'd use a little electromagnetic zapper at the hotel's front desk. The zapper programmed the domino dots on the credit card key, so that they matched up with the magnets inside a specific room lock. Change the dots and you change the key; turn the magnets off together and the key was junk. Key loss problem solved. But a Marc Tobias problem created.

To torpedo the lock company, Tobias needed to demonstrate that its tech was junk — and that any hotel using that technology had a finger in the dyke of corporate liability. To prove his tech junk idea, Tobias needed to come up with a low-fi hack that could beat the lock.

If Tobias wanted to hack into one room, he'd need to copy the magnetic fingerprint of the individual room lock. But Tobias wanted to show that the locks, the entire lock system, was worthless. So what he needed was a hack that would open every single room in the whole hotel. He needed to hack the Showa master key.

Tobias theorized that while every lock in the hotel system was unique, all of them must share a common piece of code. This common piece of code would be the master key that would be able to open all of the doors in the hotel.

He looked at each room key as a master key — each of which also had extra, unique information that would code specifically for one room and not the others. The wrong extra information essentially told a lock not to open, but * no* additional information told the lock nothing. This is why a master key, which has no additional code, opens everything — a concept familiar to anyone who's been walked in on by housekeeping.

If Tobias could collect enough room keys, he could compare their magnetic signatures and see what they had in common. Separate the common code from the extra information of individual room codes and voilà — he had a blueprint for a master key. In theory it was easy. But what was the next step?

Every Marc Weber Tobias problem is built with the basic assumption that all locks, however complicated, can be broken down into a series of simple steps; confront each in turn and you may break the lock. Now Tobias sat on the rented bedspread of Deerfield Beach Hotel, staring at the lock, breaking it down step-by-step in his mind. He knew he needed to compare the magnetic fingerprints of dozens of locks, which meant he first needed to collect those dozens of magnet fingerprints from locks up and down the hallway. This meant that he needed to invent a fast-and-dirty Showa hotel lock decoder, one small enough to fit through a credit card-sized key slot, and one smart enough to read those magnets, record the data, and present it all back to him. And he had to do it himself in his Florida hotel room.

Tobias stewed over the problem over complimentary breakfasts of mini boxes of cereal and cranny-less English Muffins, during early-bird dinners of rib tips and tap water, which usually ended with him eking out a tip using a calculator. At night he sat on the rented sheets, staring at the credit card key, turning it over in his hand. What sort of technology could he make himself that was as thin as a playing card and could decode a magnetic lock?

The answer was, duh, videotape. In fact, duh, when you thought about it, of course videotape, because that's exactly what videotape is for, reading and copying magnetic signatures. What he needed specifically was old-school, magnetic, pre-Betamax television tape. At an archaic 2 inches wide, it is the mei fun noodle of magnetic tape, more than big enough to read a credit card-sized magnetic domino.

Tobias drove around the unfamiliar town until he found a box of the stuff at a local pawn shop. Then he stopped off at a craft shop and stocked up on glue sticks and scissors, X-Acto knives and razor blades, spool wire and hard plastic. Then Tobias squirreled himself back in his hotel room to fix snippets of film onto 12 hard plastic cards. And late that night, after perving down his hallway left and right to ensure he was alone and not on camera, Tobias tested his decoder on his own rented door.

And it worked — sorta. Yes, sliding magnetic tape into the lock slot recorded a magnetic snapshot. But the act of sliding it in and out gave him the equivalent of a blurry picture. The result was imprecise enough to be useless.

Tobias sat in his room for a whole day, idly flipping through the cable package, waiting for the answer. Again and again, he came across old movies in which fedora-wearing press photographers used the old-style cameras — the kind where the unexposed film negative is encased in a sliding light shield.

Click-click, open-closed, they got a picture. It was stupid, obvious even. It always is. Tobias had been trying to take a photograph without a shutter. His missing killer app was 100 years old. He built his prototype hotel lock magnet decoder and waited.

Nothing is so dead as a Saturday afternoon in a Florida hotel, when business travelers are home and vacation travelers are beaching. The hallways belonged to Tobias. He trolled the carpet with ribbons of old-school magnetic tape encased in his jerry-rigged shutter, a long thin metal wallet with a sliding sunroof. He tiptoed door to door, in and out, stuffing each sample into his coat before trotting back to his own room. Then Tobias spread his samples on the tightly made bed and started decoding the magnetic dot configurations with his handy traveling Gauss Meter. Each of the samples was different, but all of them had one small section of magnetic dots in common, just as he'd theorized. That section had to be the master key.

Tobias razored thin rounds off a small kitchen magnet and glued the shavings onto a plastic card, one on each of the common spots he believed to be the master key code. The finished product didn't look like much, sort of a Frankenstein credit card with ladybug acne. But when the glue dried he could walk down any hall in the hotel, opening doors at random. He owned the place, him and this ugly stick in his pocket. Nobody was there. Nobody cheered. Nobody witnessed Tobias hulk out and go green and wield a little piece of plastic which could take down a company.

In fact, as Tobias remembers it, it was about six months later when the company lawyers asked what it would take for this particular Marc Weber Tobias problem to go away. The lawyer thinking: money, a contract, something with a number. It was mid-spring in South Dakota, but Tobias was still hooked on the Pearl Harbor thing. So Tobias said, simple: All he needed was for the Emperor of Japan to formally apologize to George Bush.

It didn't happen of course, it never does — Tobias has done a couple of the nationalistic torpedo things, targeting French and English companies for WWII debts and the Boston Tea Party respectively, and damn it, they never seem to work out as dramatically as you'd like, no lawyers jigging to hornpipes, no reparations or apologies or boatloads of Vichy Francs. Tobias would have to be content with the consolation that Showa no longer does business in the United States. And that nobody would have to stay in another hotel room, protected by a magnetic lock of such a stupid domino design.

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