The Cypherpunks Tapping Bitcoin via Ham Radio

Jan 11, 2021

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goTenna is advancing universal access to connectivity by building the world's most intelligent and scalable mobile mesh networks. goTenna is the world's leading mobile mesh networking company, providing off-grid connectivity solutions for smartphones and other devices, as well as augmenting traditional communications networks. This technology enables mobile, long-range connectivity without cell, wifi, or satellite connectivity. goTenna's drive to create resilient connectivity began during Hurricane Sandy in 2012 when approximately a third of cell towers and power stations in affected areas failed. goTenna's products are currently used by over 300 law enforcement, military, and public safety agencies worldwide. goTenna is backed by investors including Founders Fund, Union Square Ventures, Comcast Ventures, Collaborative Fund, and Bloomberg Beta.

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Every six hours, at his home in the high desert outside Kingman, Arizona, midway between Phoenix and Las Vegas, Brian Goss downloads the latest blocks from the bitcoin blockchain via satellite. He receives the transmission through a dish he installed this January; it arrives with messages, too---tweets, blogs, odes to Satoshi---sent by bitcoiners around the world. Goss rebroadcasts them from a radio device perched on his roof, in case the neighbors care to tune in. There’s nothing wrong with Goss’ terrestrial internet connection, he assures me---Kingman is not that remote. But if bitcoin is truly digital gold, as he believes, contingencies are important. If the internet goes down, how else will you access your cache?

For some, the trouble with bitcoin, the internet’s native currency, is the internet. Sure, bitcoin may be “decentralized,” with copies of its ledger stored on computers all over the world. But is it really decentralized if it relies on the pipes of your local internet provider? For those wary of tracking and censorship, analog signals---through satellites and land-based radio devices---offer a welcome buffer from central control. Plus, if you believe that bitcoin, which is again worth more than $10,000, is the right place to store your wealth, satellites offer the comfort of redundancy.

The idea isn’t totally irrational. Consider India, where officials recently proposed jailing people for 10 years for using bitcoin. Or Egypt, where the government unplugged the internet in 2011. Perhaps you live on a remote island tethered to the internet by a single undersea cable, or a place without any internet access at all.

Bitcoin’s celestial coverage comes from Blockstream, a blockchain software company. To be clear, Blockstream isn’t launching satellites itself; it rents a small portion of the bandwidth on commercial satellites, which are mainly used for TV. The data is beamed up with enough bandwidth to ensure the blockchain stays up to date. Users can also send along messages, paid through the Lightning Network, a technology that allows small bitcoin payments. The satellites broadcast the signals back down to whoever might be listening.

Listening is the hard part. “It was super outside my technical skill,” says Goss, a radiologist by day. “I didn’t know anything about any of this.” It took him about a week to install the equipment, which he estimates would cost about $100 to buy new. He mostly used spare parts: a 2014 Mac Mini and an idle satellite dish that came with the house. (“We’re not much of a TV family,” he says.) There was some fiddling with software and a few hours of drilling in the equipment, but most of his time went into figuring out where to point the thing.

“This is why you hire someone to install DirectTV,” says Elaine Ou, a blockchain engineer who set up a receiver, with no small effort, at her Bay Area home. Beyond cypherpunk cred, there are practical reasons for receiving blockchain by satellite, she says. Cryptocurrency exchanges have been hit with so-called partition attacks, where data is surreptitiously delayed or faked, knocking the targeted computers out of sync with the rest of the blockchain network. Those attacks happen over the internet, so having an alternate, analog connection means you’re less likely to be fooled.

Ou first started experimenting with alternative ways to send and receive bitcoin back in 2016, around the time China was considering a cryptocurrency ban. Recalling the difficulty the Soviets had jamming American radio transmissions, she and her colleague Nick Szabo, a well-known digital currency researcher, devised a plan to bypass the Great Firewall by sending bitcoin transactions via ham radio. The method offered at least one advantage over satellite: Satellites let you receive data without an internet connection, but you can’t use them to send.

The Chinese ban never materialized. But in March, Ou was able to test out the concept, sending a Lightning payment over the airwaves to an engineer in Toronto. The process wasn’t exactly seamless, she says. It required plenty of coordination over Twitter and Telegram to ensure they communicated across the same narrow band. And it’s not much good for maintaining stable access to your digital hoard, either; low bandwidth means you can’t transmit the data fast enough, so you’ll end up falling behind the network as it updates. She says she’ll stick with satellite for that.

GoTenna, a startup known for making communication devices used in natural disasters, thinks it has an answer to the send-and-receive problem of satellites: radio mesh networks, which work by relaying information over short distances from person to person. The company, which mainly deals with text messages, started supporting bitcoin transactions last year, and it recently partnered with Blockstream to let people use GoTenna’s device to rebroadcast the satellite data they receive.

For now, bitcoin is “still kind of niche” in the mesh networking community, says Richard Myers, who engineers “decentralized applications” for GoTenna. But the company is also exploring how bitcoin could be used to incentivize people to build mesh networks in places with low connectivity. Basically, you’d get paid for forwarding somebody else’s texts.

For now, Goss is happily part of that niche. He tunes into the Blockstream dispatches from time to time: There’s a person who blasts out the news of the day, and a user in Eastern Europe transmits regular blogs. On the anniversary of the Tiananmen Square massacre, someone broadcast the Wikipedia article about the event, in case anyone in China was listening. Sometimes the messages are encrypted, seeking out a listener with the keys. “It’d be a great thing for a spy,” Goss muses. “Plausible deniability.” He does his part by broadcasting the messages down to the interstate, which is just within range of the GoTenna. Anyone driving by with a device set to listen will carry it with them to Vegas or Phoenix.

For the most part, the conversation is idle and directionless, sporadic on its most active days and entirely one-sided. Why listen at all? Goss tells me about mining bitcoin nine years ago, when the cryptocurrency world was so small that his home desktop at times made up 1 percent or more of the computing power on the network. It was an era before massive bitcoin mines, before billion-dollar crypto funds, before a Facebook cryptocoin. “This is what bitcoin felt like back then,” he says.

— Wired