Cyber security experts say bitcoin will disappear when the first quantum computer appears.
A quantum computer processor is pictured without its protective thermal canisters at D-Wave Systems' lab in Burnaby, British Columbia, Canada, March 11, 2013.KIM STALKNECHT/NEWSWEEK/REDUX
Rumors of bitcoin’s demise
have been greatly exaggerated. According to a site tracking “bitcoin obituaries,” the media has
proclaimed the seven-year-old cryptocurrency dead more than 100 times, yet a
recent resurgence has led to a tripling in bitcoin’s price over the last
year. It has survived price crashes, cyber heists and community infighting, but
bitcoin’s biggest threat may still be lying dormant: quantum computers.
Since they were first
theorized by the physicist Richard Feynman in 1982, quantum computers have
promised to bring about a new era of computing. It is only relatively recently
that theory has translated into significant real-world advances, with the likes
of Google, NASA and the CIA working towards building a quantum computer.
Computer scientists are now warning that the arrival of the ultra-powerful
machines will cripple current encryption methods and as a result bring a close
to the great bitcoin experiment—collapsing the technological foundations that
bitcoin is built upon.
“Bitcoin is definitely
not quantum computer proof,” Andersen Cheng, co-founder of U.K. cybersecurity
firm Post Quantum, tells Newsweek. “Bitcoin will expire the very day the first quantum
computer appears.”
The danger quantum computers
pose to bitcoin, Cheng explains, is in the cryptography surrounding what is
known as the public and private keys—a set of numbers used to facilitate
transactions. Users of bitcoin have a public key and a private key. In order to
receive bitcoin, the recipient shares the public key with the sender, but in
order to spend it they need their private key, which only they know. If
somebody else is able to learn the private key, they can spend all the bitcoin.
“If you have a quantum
computer then you’re able to just basically calculate the private key from the
public key,” says Martin Tomlinson, a professor in the Security, Communications
and Networking Research Centre at Plymouth University. “It would take just a
minute or two. So by learning all the private keys using a quantum computer,
you’d have access to all the bitcoin that’s available.”
Tomlinson doesn’t have a date
for when he believes the first quantum computer will appear that is capable of
doing this, but points to vast research efforts currently underway that are
bringing them ever closer. Earlier this year, a new €1 billion ($1.1 billion)
project was announced by the European Commission aimed at bringing about a
“quantum revolution.”
Some companies, most notably
Canada’s D-Wave, claim to have already built quantum computers, however,
leading computer scientists contend that the machines should not be referred to
as such. Tomaso Calarco, director of Integrated Quantum Science and Technology
recently told Newsweek that “D-Wave’s machines
are not recognized by the scientific community,” but Ilyas Khan, co-founder of
Cambridge Quantum Computing said that it is “only a matter of relatively short
time” before quantum technologies become of practical importance in the real
world.
To safeguard bitcoin from
quantum computers, new quantum cryptography standards will need to be
incorporated into the bitcoin protocol. Such quantum-proof technologies already
exist; the issue will be with introducing them. Llew Claasen, executive director
of the Bitcoin Foundation, says “many very smart cryptographers” are already
working on a solution and that quantum proof technologies could potentially be
phased in to the network gradually. However, Tomlinson disagrees, pointing to
existing problems with bitcoin that have yet to be solved.
“It will be doomed,” Tomlinson
says. “Any disruption needs the consensus of the bitcoin community and that
can’t even be realized when it comes to the transaction limit problem . That’s a relatively
simple problem compared to redoing the entire digital signature method.
“It’s probably impossible, so
bitcoin has had it.”
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