Imagine a woman—Max, we’ll call her—is lost in the forest. She’s walking down a path looking for her cabin and every time she takes a step, she must pick which fork in the road she wishes to take. She can walk myriad paths, but she will only find her cabin if she picks a specific combination of “correct” paths. Computers work the same way—they use algorithms to guess at different solutions, and use different paths to arrive at the same conclusion.
So, an algorithm to find Max’s best path through the forest to her cabin might look like this: First, make lefts at all forks. Then, if you haven’t reached the cabin, start again, and make a right at the first fork, but otherwise keep making lefts. If you still aren’t there, start again, make two rights, then make all lefts—and so on. This could take some time, and that time depends on how many forks in the road she will encounter.
On the blockchain, miners are effectively using computers to guess at different paths each time they solve a verification process. They test a number of paths, but once the solution is found, it’s relatively simple to look back and be sure that the path they took worked.
As time goes on, the paths continue to get more difficult—there may be trees in the way, a river to cross, and a large hill to climb at the end. It would be really difficult for Max alone to navigate this winding path to find the cabin, but the computer can do it efficiently by testing a number of algorithms.
On the blockchain, it’s a good thing that the paths to the cabin get increasingly complex—it requires many computers, each with a lot of computational power to function. This increases the blockchain’s security because it prevents one person or group from seizing too much power.
This method of navigation works well for now. But what if a new method of navigation emerged that upended the entire way Max arrived at her destination? What if Max could use a helicopter to find the path back to the cabin instead?
Quantum computing is effectively that helicopter—it would allow Max to see all possible routes back to her cabin all at once, because she could now view the problem from a different plane (no pun intended). Instead of taking the time to test many possible paths on the ground—wading into the river or hiking back up one of the hills to get a better vantage point—from the helicopter, she can spot her cabin almost immediately. She can even see each possible route that she could have taken from the ground and mark it on her map for later.
Using a quantum computer to mine bitcoin is like bringing a helicopter to a foot race—the quantum computer will trounce the competition every single time.
Quantum computing is a truly mind-blowing technology. I like this explanation from Motherboard:
“Present day computers are limited by their hardware. They use electrical circuits that are switched on or off, in a 0 or 1 position. Quantum computing would change that by using particles called qubits, which are suspended in a super-cold environment where the temperature nears absolute zero. The network formed by these particles allows for processing power to grow exponentially, as the qubits can be simultaneously at a 0 and a 1.”
Tasks that supercomputers find challenging today—like verifying transactions on the blockchain—are painfully simple for the quantum computer. This could have far-reaching consequences. A 4,000-qubit quantum computer, for instance, could break the blockchain. The first person or group to have access to a powerful quantum computer could both solve and verify each additional transaction, which could allow them to monopolize all remaining future bitcoin not yet in circulation and eliminate the cryptocurrency’s system of trust, since power would no longer be distributed across the network.
“But Natalie, we’re a long way off from quantum computing being possible,” you say.
Ten years! And Google has even thrown the gauntlet—recently claiming that it’ll produce a commercially viable quantum computer in just five.
In the early 2000s, the general consensus was that we were at least 30 to 50 years away from a functional quantum computer. However, as I wrote about in a previous Medium post, technology is changing at an accelerating rate. So it makes sense that the advances toward quantum computing are compounding quickly year over year. In 2018, we might only be 5% of the way there, but next year, we could be 10%, the next year 30%, and so on. Then boom—it’s 2028. The Time magazine cover reads, “Year of the Quantum Computer.”
At the Crypto 2017 Conference, a meeting of the world’s leading blockchain cryptographers, in November, “nobody seemed too concerned” over the risk quantum computing may pose, according to a Fortune report. One expert said it would be a “very expensive operation” and likely require “government level” spending, “while another expert, who also asked to remain nameless, scoffed at the idea completely, waving a hand and saying by the time quantum computers become available, public key cryptology will have advanced too far for it to matter.”
The experts have a good point here—the advent of quantum computing will jeopardize the security of all existing cryptographic encryption methods, including RSA tokens. Quantum computers will affect the security of the entire finance and banking industry, not just the blockchain.
Even so, I’m surprised that security is not a more common conversation throughout the blockchain community. For a group deeply rooted in futurism, this seems shockingly shortsighted. It feels as if we’re building the blockchain for the next 50 years, but what if we only get to the next five or 10? What can be done to ensure that blockchain is dynamic enough to outlive quantum computing?
Here’s one thought: We need to focus less on trading and more on building quantum-resistant platforms. For every one creator there are 100 crypto-junkies riding the token-trading wave with little understanding of the horses they are betting on. Unfortunately, the crypto-junkies are making money—lots of money—and the bright, shiny objects are distracting us from the industry-changing Model T being developed around the corner.
I’d like to issue a challenge to the blockchain community: Pretend, for the sake of argument, that quantum computing will be viable by 2028. What adaptations need to be made to ensure that the nascent blockchain industry will stand the test of time? Where should we focus over the next six months? The next year?
It’s time for less trading and more building. Go forth and create, but create with a quantum future in mind.
Natalie Fratto is the vice president of the Early Stage Practice at SVB Financial Group.