Does quantum computing break the blockchain?

Blockchain is just the latest technology that will change the way we work and live, but there is a new technology that is starting to emerge and, according to the researchers, it looks set to destroy the disruptor. That technology is quantum computing. Recently, an article by computer scientists published in the journal Nature even suggests that the blockchain could be rendered obsolete by quantum computing.

Scientists say that within a decade, quantum computers will be able to break the cryptographic codes of a blockchain. Bearing in mind that by 2025, up to 10% of global gross domestic product is likely to be stored on blockchain, the size of the problem becomes clear.

What the Blockchain do

Blockchain is a structure for storing data in which groups of valid transactions, called blocks, form a chronological chain, with each block cryptographically linked to the previous one. Although it has been widely associated with bitcoin and cryptocurrency, it is also increasingly used to store business data.

Blockchain is first and foremost a public (or sometimes private or hybrid) database open and decentralized. Open means that anyone can read it unconditionally and anyone can write it after fulfilling certain conditions. There is no governing body that can arbitrarily modify data, nor does there exist a single point of error from which the database can be hacked or destroyed.

The data in the blockchain can be opened or encrypted and readable only by those for whom it is intended. Quantum computing, however, could change everything.

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What the quantum calculation will do

Quantum computing poses a threat to blockchain technology because it reduces the underlying security assumption of elliptic curve cryptography, meaning that computers can not effectively count on large numbers, said Adam Koltun, chief strategist of the cryptocurrency Quantum Resistant Ledger.

In today's traditional and legacy blockchains, the most common form of public / private key mapping is based on the Elliptic Curve digital signature algorithm (ECDSA). ECDSA works on the assumption of safety that computers, even the very powerful ones, can not break down large numbers in terms of human time and break the blockchain keys. Most legacy blockchains are based on ECDSA.

In ECDSA public key cryptosystems, anyone can send transactions or messages to a public key, but only the owner of the paired private key can access what has been sent to the public key / address. It's like a mailbox – anyone can enter letters in the front slot, but you need the (private) key to open the back and take anything out of it. "The security of a blockchain is guaranteed by its cryptographic functions and the most common in the industry is at risk in the face of quantum computing, and, unlike centralized systems, decentralized systems require active consent and the participation of all. users to get something like total address type migration, which is what would be needed to achieve quantum resistance, "he said.

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Quantum calculation limits

Alexander Leo-Hansen, founder and CEO of Coinbox.dk, a digital bitcoin / Ethereum vendor, said that while quantum computing poses a threat, it is not the only technology at risk. Banks, companies and countries that use blockchain will be targeted if they develop to the point where quantum computers can unveil blockchain codes. But, he said, it will not go that far. There are two reasons:

1. Advanced cryptography: Quantum Computing will soon be a reality. It can, and will be used to break the current standard that is RSA. However, if quantum computing is applied to cryptography, cryptography becomes tighter and it becomes harder to break blockchain codes.

2. Blockchain society: IBM, Google and a number of other technology giants are the current engines in the development of quantum computing. It is likely that they will not allow users of quantum computing to decrypt cryptography or bank blockchain. "Doing this is illegal and would destroy those companies, I believe every cryptography in the future [system] it will be improved by quantum computing. Blockchain is getting better day by day, "he said.

The theoretical threat goes beyond the blockchain

In practice, quantum computing is only a marginal threat, said Gabriel Bianconi, founder of Scalar Research and researcher of quantum computing. Public-key cryptography is a common technique used for cryptography and authentication. Internet connections (HTTPS), blockchain and many other applications use this technique. In most cases, their security is based on complex mathematical problems such as integers of integers, which can not easily be deciphered by a traditional computer.

In theory, a sufficiently powerful quantum computer would, however, be able to solve these problems efficiently. If that happens, he said, the problem is much bigger than just bitcoin: people would be able to decipher most of the cryptographic forms used today. However, there are two reasons why this is not an immediate concern:

1. Maturity of quantum calculation – This calculation is still in its infancy. A sufficiently powerful quantum computer will not necessarily be available by 2025.

2. Safe algorithms for quantities – There are other cryptographic algorithms called quantum-safe or post-quantum algorithms that can not be deciphered by quantum computers. There are cryptocurrencies that are already experimenting with these technologies (eg QTUM). If quantum computing becomes a risk, the bitcoin would probably switch to a similar algorithm.

The long-term threat of Quantum Computing

Predicting the future is difficult. Building a quantum computer is extremely challenging, but the potential to solve important problems that classic computers are not able to solve is motivating large companies to spend a lot of time and resources to be the first to be able to build one, and progress has been done quickly.

Tim Hollebeek, DigiCert's technical strategist and industry strategist, points out that, unlike classical computers, quantum computers are best at solving some very specific problems. However, for these problems, they are far better than classic computers will ever be. Examples include the simulation of other processes of quantum mechanics, the resolution of complex interconnected equations for meteorological forecasting or artificial intelligence and the factoring of very large numbers.

It is likely that quantum computers capable of solving interesting problems will emerge in the coming years. Those that can threaten modern cryptographic algorithms are farther away, but could arrive no earlier than seven or ten years.

The most important danger is that both the asymmetric cryptographic algorithms (RSA and ECC) that underlie all the modern cryptography of the world are weak defenses against quantum computers. Now that actual quantum computers are becoming a reality, cryptographic systems will have to switch to new cryptographic algorithms designed to be strong against quantum computers. "It's hard to overemphasize the scale of this transition – virtually all our cryptographic software and hardware will need to be rebuilt and replaced in the next decade or two," he said. "It will be a long and complex process and industry experts are working hard to prepare for this important transition."