Police Garage Door Tip
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Police Garage Door Tip

Paul Skelton, 37, was fed up. It was the second time thieves had stolen a bicycle from his garage. The first time, they broke in. This time, they walked in – they cracked the garage door opener code. Paul didn’t realize that his old style opener was easy to hack. The police have a tip for people like Paul – use a modern garage remote that defeats hackers.

Police Garage Door TipPaul did some research before calling his Skokie IL garage door repair guy. He learned how thieves got the old opener to open – they stole the transmission. Old style remotes use a fixed numeric code that translates to specific set of radio frequencies. This allows eavesdroppers to mount a replay attack, in which they record the remote’s transmission and replay it later when you’re not home. The dumb old opener thinks the transmission is authentic and faster than you can say “open sesame”, your garage door is wide open and your bicycle is gone. Pretty clever, but definitely old school.

The solution is to use a modern remote that incorporates rolling code technology. A new code is transmitted each time the garage door is opened, so eavesdropping won’t do a criminal any good. Here’s how it works:

  1. The opener has a logic circuit that creates an encrypted random number in the remote and the opener.
  2. The remote transmits what is called the “next” sequential code.
  3. The opener compares this code with what it expects as the next code.
  4. If they match, the door opens.

It’s actually a little more complicated, involving radio frequency transmissions composed of fixed and rolling codes. By comparing the received transmission with pre-stored codes, the opener can decide whether the transmission is legitimate. Thieves can still find a way into your garage if you give them enough time, but it won’t be through eavesdropping. Paul specified the newest model opener and remote, which the repairman was happy to install. His model works at the 315 MHz frequency range, which means it avoids interference from frequencies used by the U.S. military. The new remote works fine and the opener is much quieter than the old one.

Even though the new technology solves one crime problem, police offer a second tip: remember to close your garage door. Believe it or not, police report that the majority of thefts from garages occur because the owner left the door open! Let’s all try remembering to close our garage doors – don’t make it too easy for the thieves.