Is quantum computing the end of the blockchain?

What is the Blockchain?

There is a lot of hype around the blockchain and how it is changing the world, the economy and how we do things, and for good reason! It promises freedom and independence in a self-sustaining, self-regulating and self-governing system that you can visualize by watching this nicely explained video:

There are tons of great materials on the web explaining the blockchain, what we will talk about though is the blockchain's core principle, the hashing mechanism, which is an encryption method.

What is Cryptography?

Encryption dates back to the 1900 BCE, however it's use and power became evident in World War II with the invention of the Enigma Machine that allowed the Nazi army to communicate over great distances without the Allies understanding their messages.

If you're interested (and you should be) you can read more on that over here

The basic principle behind encryption is that you have a message that you would like to obfuscate so you pick an algorithm that will be your obfuscation method and a complex set of characters that will be the key to understanding the message. Nowadays encryption produces two keys though in order to resolve the communication problem:

• a private key that can be used to decrypt the message
• a public key that can be used to encrypt it.

By using the public key (which you share in order for people to be able to send you encrypted messages that only you can read) one could figure out the private key, however that would take years to do using today's processing technology.

I'm probably talking to people who are mining cryptocurrency and are very familiar to this whole process, but I needed to make sure these concepts are sort-of understood before talking about the elephant in the room.

What is Quantum Computing?

A great explanation of quantum computing is available in the following video:

Quantum computers don't seem to make much sense for every household, since the classical bit computer has more than enough power for every day tasks. What quantum computers seem to be aimed for is transforming logarithmic problems into linear ones, essentially bringing NP problems into polynomial time.

How far are we from Quantum Computing?

Back in 2016 researchers in Australia started putting Qubits on silicon chips which is a great step forward since silicon is readily available and cheap, all the major players (Google, Intel, China) are pouring lots of money into this technology, and IBM just pushed its supercomputer to 16 qbits.

Why should we care?

There are two important points where a quantum computer can attack cryptocurrency:

1. The private key

If someone had the computing power of a quantum computer he could deduce your private key from your public one, getting access to your wallet and encrypted communication making the whole system obsolete and futile.



For communication it would seem there is still some hope by using quantum entanglement, a connection that collapses when you measure it making it viable to send information from Bob to Alice knowing it can't get to John while in transit, but it would still pose the problem of John spying on either Bob or Alice directly to get the data.

2. The blockchain trust

The trust of the blockchain comes from the fact that no one individual or group (unless he's able to perform a 51% attack) can modify the previous blocks because the computational power to generate the hashes for let's say 10 blocks is too great, making it close to impossible to achieve using the current computers. That becomes a non-issue once we bring quantum computers into the mix, breaking the user trust in the blockchain.

What's next?

Quantum computers are great, they will help us solve a lot of unanswered problems but it's quite clear they will also create a few. Maybe a new way of encrypting is available in the quantum world, one that we are yet to discover, and maybe we need a quantum computer to do it.

What is your take on this subject? Hit me back in the comments below!

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