The massive calculating power of quantum computers will be able to break Bitcoin security within 10 years, say security experts.
A crucial feature of Bitcoin is its security. Bitcoins have two important security features that prevent them from being stolen or copied. Both are based on cryptographic protocols that are hard to crack. In other words, they exploit mathematical functions, like factorization, that are easy in one direction but hard in the other—at least for an ordinary classical computer.
But there is a problem on the horizon. Quantum computers can solve these problems easily. And the first quantum computers are currently under development.
That raises an urgent question: how secure is Bitcoin to the kinds of quantum attack that will be possible in the next few years?
Today, we get an answer thanks to the work of Divesh Aggarwal at the National University of Singapore and a few pals. These guys have studied the threat to Bitcoin posed by quantum computers and say that the danger is real and imminent.
But there is a different threat that is much more worrying. Bitcoin has another cryptographic security feature to ensure that only the owner of a Bitcoin can spend it. This is based on the same mathematics used for public-key encryption schemes.
The idea is that the owner generates two numbers—a private key that is secret and a public key that is published. The public key can be easily generated from the private key, but not vice versa. A signature can be used to verify that the owner holds the private key, without revealing the private key, using a technique known as an elliptic curve signature scheme.
In this way, the receiver can verify that the owner possesses the private key and therefore has the right to spend the Bitcoin.
The only way to cheat this system is to calculate the private key using the public key, which is extremely hard with conventional computers. But with a quantum computer, it is easy.
And that’s how quantum computers pose a significant risk to Bitcoin. “The elliptic curve signature scheme used by Bitcoin is much more at risk, and could be completely broken by a quantum computer as early as 2027,” say Aggarwal and co.
Indeed, quantum computers pose a similar risk to all encryption schemes that use a similar technology, which includes many common forms of encryption.
Read more here: www.technologyreview.com/s/609408/quantum-computers-pose-imminent-threat-to-bitcoin-security/