Quantum Computers: A Threat to Blockchain?

In this article, I will look into quantum computers and their potential threats for blockchain projects.

The Concept of Quantum Computers

In 1982, the Nobel Prize winner Richard Feynman suggested how a quantum computer would be used in the modern world.

Just a year later, Apple introduced the “Apple Liza” – a home computer with a 7.89MHz processor, 5MB hard drive and a floppy drive.

Today we walk with portable devices that are thousands and millions of times more powerful, but our modern computers work in the same simple manner, simple math and with the same simple operators. They do it faster and more efficiently, so we forget what happens behind the scenes.

However, so far, in spite of this development, modern computers cannot crack cryptocurrency without the use of vast processing powers.

However, is this true for quantum computers?

To get a better understanding, let us look on Bitcoin address as a prime example.

What is a Bitcoin Address?

A bitcoin address is used to send and receive bitcoins. However, it consists of two parts.

A public key that is visible in general ledger and is needed for accepting payments and a private key that is obtained from the public key.

The private key is 256 bits of information in a random sequence. This 256-bit code consists of 64 characters (within 0-9 / a-f) and further compressed to a 52-character code (using RIPEMD-160).

Even though many people talk about Bitcoin encryption, Bitcoin does not use a hashing algorithm.

The bitcoin address “1EHNa6Q4Jz2uvNExL497mE43ikXhwF6kZm” is translated into the private key “5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAnchuDf”, which is then converted in 256 bits private key.

Now, to get access to this Bitcoin address, you first need a private address and, second, a public address obtained from this private key. Meaning by knowing the private address, you can find about the public address.

In addition to this, there is a technically proven theory that due to this “compression,” different private keys/addresses can be used to access the same public key (aka address). This means that your bitcoin address does not have one private key associated with it, but several, and if someone accidentally finds or hacks one of them, then this hacker will get access to all the BTC on this address.

It should be noted that the probability of finding a Bitcoin address with at least some means (or at least used) is minimal, although it is still possible!

How Can a Quantum Computer Pose a Threat?

There are two main concepts behind the quantum computer: superposition and quantum entanglement.

The superposition allows a quantum bit (qbit) to be in several states at the same time, and with the help of quantum entanglement, the observer can find out the parameters of a particle in any position in the universe. The connection is preserved, even if they are moved into different parts of the Universe.

In essence, a quantum computer can process and analyze infinite bits of information at the same time — and so quickly and differently than the human mind cannot grasp it.

How Can You Protect Yourself?

Of course, the best option is to sit straight and watch how Bitcoin and other blockchains introduce new cryptographic features to protect from potential quantum computers threat, but it takes time, and this process can be long at the scaling level.

Another option that can be implemented is to use the blockchain address only once to send a transaction. When quantum computers attack Bitcoin (and other cryptocurrencies), their first target will address that have outgoing transactions on the blockchain, which contains assets.

This is because when the computer first tries to crack the bitcoin address, the starting point is the moment when the transaction becomes public. In other words, this happens when a transaction is “signed up” for the first time — this digital signature, which is formed from a private key and confirms the transaction within the network. Compared to conventional computers, quantum computers could quickly process this information.

Initially, Bitcoin Core software can provide a certain level of protection because it uses only one address and then sends the remainder of funds (if any) to another address in your pool. However, third-party wallets can and use the address several times for outgoing transactions. For example, this can be a big problem for users who accept donations (unless they update their address every time they withdraw funds from there). The biggest drawback of Bitcoin Core software is the amount of space required on the hard drive, as well as the careful saving of updated copies of the entire blockchain. However, as quantum computers evolve, they will inevitably turn SHA256 into one significant vulnerability, and although this will be one of the first hashing algorithms hacked by quantum computers, it will not be the last!

Bottom Line

Developers in the crypto space are fully aware of quantum computer threats, and there are several projects that want to create quantum resistant blockchain, although currently, the main focus lies with other blockchain issues like scalability and transaction speed.

Featured image courtesy of Shutterstock. 

Vladislav Semjonov has a legal and financial background. He has been involved in crypto space since early 2017 in both ICO advising positions in several ICO consultancy firms, and as an ICO analyst for VC. He began contributing for Hacked.com in April 2017.