The Arrival of Quantum Computing - Threat to Bitcoin?

IBM has recently announced that it has opened up its 5-qubit quantum computer to the general public. Has quantum computing finally arrived and what impact will it have on Bitcoin?

Quantum computers

Quantum computers represent a new paradigm in computing.

While traditional digital computers store data in binary bits (zero or one), quantum computers store data in the form of qubits (where 2 data states can be superimposed.).

This enables large scale quantum computers to solve certain mathematical problems in a much more efficient way compared to traditional computers.

Asymmetric cryptography - the key to Bitcoin

The Bitcoin protocol uses asymmetric cryptography to ensure that bitcoins can only be spent by their rightful owner. Transactions signed by a private key can be verified using the corresponding public key.

Brute forcing private keys corresponding to a given public key using currently available computers is infeasible. While bitcoins have been lost by users to hackers, it is mainly due to the unsafe security practices of users.

However, asymmetric cryptography is one of the problems that can be solved efficiently by an effective quantum computer.