# Quantum computers and digital currencies; Everything you need to know

Quantum computers are powerful machines that have much greater ability to solve complex problems than ordinary computers. Some experts estimate that these computers can crack encrypted passwords in minutes; The work that today’s fastest computers need to do at least a thousand years to do. Therefore, these new computers are likely to jeopardize the security of the digital space, especially the underlying encryption of Bitcoin and other digital currencies.

This Content Published on the Binance Vision website, it first explains the difference between quantum computers and ordinary computers, and then examines the risks that these computers can pose to digital currencies and other digital infrastructures.

## Asymmetric encryption and Internet security

Asymmetric cryptography (also known as public key cryptography) is a very important component of the digital currency ecosystem and Internet infrastructure. This is done with a pair of keys to encrypt and decrypt the information, called the public key and the private key, respectively. In contrast, we have symmetric encryption that uses only one key to encrypt and decrypt the data.

In asymmetric encryption, we can give the public key to others and use it to encrypt information. But then, decryption of this information is possible only with the private key corresponding to that public key. This ensures that only the key holder can access the information.

One of the main advantages of asymmetric cryptography is the ability to exchange information without having to share a public key in a trusted channel. Without this very important feature, it is impossible to secure information on the Internet. For example, it is even difficult to imagine having online banking without securely encrypting information between unreliable parties.

Asymmetric encryption is secure because the key-pair algorithm makes it extremely difficult to calculate the private key from the public key, while it is easily possible to calculate the public key from the private key. Consider this example: The answer 250 plus 250 is certainly equal to 500, but how many cases are there that add two numbers together to be 500? Obviously, there are many choices. This is what in mathematics is called the Trapdoor Function. A function that is very easy to calculate on the one hand and very difficult on the other.

Currently, the most advanced algorithms for generating key pairs are based on the valve function. Solving these valve functions is not possible for current computers at any time. Doing these calculations takes a lot of time, even for the most powerful machines.

However, with the development of new computing systems called quantum computers, the situation is likely to change soon. To understand why quantum computers are so powerful, let’s first look at how ordinary computers work.

## Classic computers

The computers we all know and use are called classic computers. The calculations on these computers are done sequentially, ie first a computational task is performed and after that, the next calculation starts. This is because the memory of classical computers must follow the laws of physics and therefore can only accept one of two modes, 0 or 1 (on or off).

Various hardware and software allow computers to break down complex computations into smaller pieces to increase system performance. But the principle of the work does not change, one computational task must always be completed to begin the next.

Let’s take an example:

Suppose a computer wants to guess a 4-bit key. Each of the four bits can be 0 or 1. So there are 16 possible scenarios shown in the next image.

The classical computer can only guess one at a time and try each one separately. If it’s still unclear to you, suppose you have a lock with a keychain that has 16 keys. You must try each of the 16 keys separately. If the first one does not unlock, you try the next one and so on until the end.

The situation is the same with classic computers. In fact, as the key length increases, the number of possible combination states increases exponentially. In the example above, by adding just one bit that will make the key 5-bit, the number of states will increase from 16 to 32. Adding another bit will give us 64 possible modes. It is estimated that at 256 bits, the number of possible states will be equal to the number of atoms in the universe. Can you imagine what a big number we are facing?

As the number of states increases exponentially, the processing speed of the computations increases linearly. If you double the processing speed of the computer, the number of guesses made over a period of time will double, which is definitely not noticeable at all as the number of states increases.

It is estimated that a classical computing system would take thousands of years to guess a 55-bit key. The minimum recommended size for a Seed statement in Bitcoin is 128 bits and for many wallets it is 256 bits. This means that it is almost impossible to guess these phrases. Therefore, it seems that classical computing can not threaten asymmetric cryptography used in digital currencies and Internet infrastructure.

## Quantum Computers

Quantum computers are a group of computers that are very easy to solve the above problems. These computers are still in the early stages of development.

The principles on which quantum computers are based are the same principles of how subatomic particles behave that can be explained through the theory of quantum mechanics.

Classic computers use bits to represent information that can accept one of two values, 0 or 1. Quantum computers work with quantum bits or qubits. Qubit is the basic unit of quantum information processing in quantum computers. Just like bits, qubits can accept two values, 0 or 1, except that thanks to the strange behavior of quantum mechanical phenomena, qubits can have both values 0 and 1 at the same time.

Because of this interesting feature, universities as well as private companies have devoted a lot of time and energy to this new field to conduct research and development in the field of quantum computing. Dealing with the problems that exist in the abstract theory and engineering operations of this field is one of the most advanced human technical achievements.

Unfortunately, one of the downsides of quantum computers is that they are likely to be able to easily solve the algorithms that underlie asymmetric cryptography. This puts systems based on these algorithms at risk.

Let’s take the example of a 4-bit key again, except that here we have qubits instead of bits. A quantum computer would theoretically be able to compute 16 different states at a time. The probability of finding the correct answer within the time when this computational task is completed is 100%.

## Cryptography-resistant cryptography

The development of quantum computing technology could undermine asymmetric cryptography, which forms the basis of most of our modern digital infrastructure, including digital currencies. This technology can endanger the security, operations and communications of the whole world, from governments and multinational corporations to ordinary users. It is therefore not surprising that so much research is being done to find countermeasures against this technology. These cryptographic algorithms, which are supposed to be safe from the threat of quantum computers, are called “quantum resistant” algorithms.

It seems that the risk of quantum computers can be reduced by symmetric encryption through a simple increase in key length. As you know, in symmetric cryptography there is only one key that is used for cryptography and decryption. There are risks involved in sharing this public key in the open. As a result, this method was abandoned and replaced by asymmetric cryptography. Due to the mathematical relationship between the two keys in asymmetric cryptography, the general key length in this method must be much longer than the key length in symmetric cryptography to provide a high level of security. For this reason, after the advent of quantum computers, we may have to use symmetric cryptography again.

On the other hand, research is underway to find ways to deal with eavesdropping. Eavesdropping in an open public channel will be identical to the same principles and methods needed to develop quantum computers. This way you can probably tell if a symmetric public key has already been read or tampered with by a third party.

In addition, other research is underway to counter possible quantum-based attacks. This research focuses on methods such as hashing (using hash function) to create large-scale messages, lattice-based encryption, and the like. The goal of all this research is to develop a variety of encryption methods that are difficult for quantum computers to crack.

## Quantum computers and bitcoin mining

Cryptography is also used to extract bitcoins. Miners perform calculations to solve a cryptographic puzzle in exchange for block rewards. If a miner accesses a quantum computer alone, he or she may dominate the entire network. This reduces network decentralization, thus putting the network at a 51% risk of attack.

However, according to some experts, this threat may be the last thing we need to worry about. ISICs (integrated circuits with special applications) can reduce the impact of such an attack, at least in the near future. In addition, if multiple miners access quantum computers, the risk of such an attack is significantly reduced.

## Conclusion

It seems that only time will tell what problems quantum computing will create for current asymmetric encryption. However, there are huge theoretical and engineering barriers that must first be overcome before worrying about threats.

Since there are many threats to information security, it makes sense to start taking action against attack vectors in the future. Fortunately, extensive research is being done on potential solutions that can later be embedded in existing systems. These solutions could theoretically protect our critical infrastructure against quantum computers and are unlikely to become obsolete over time.

Quantum-resistant standards can be made available to the public in the same way that well-known browsers and well-known encryption messaging applications flourished. Once these standards are finalized, the digital currency ecosystem can be integrated with the strongest possible defense against these attack vectors.

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