What is quantum communication
Let's start with the basics and take a look at the phrase itself.
The most developed direction within the technology- quantum cryptography, or, more precisely, quantum key distribution. This is a set of methods aimed at generating a shared secret key between remote users, which is then used for encryption.
Another task of quantum communications is the transmissionquantum information between quantum computers. Technologies are smoothly moving toward the development of distributed quantum computing, that is, the creation, for example, of a central quantum computer and many peripheral machines that solve some subtasks and transmit data to each other. An alternative to this could be a set of interconnected remote quantum processors. In February 2021, a group of researchers from Germany demonstrated the possibility of transferring quantum information between two modular quantum processors. The results of the experiment were published in the journal Science. This is an important step in the development of technology, which showed that it is possible to increase the power of quantum computing technologies by combining several devices into a network.
An interesting technological feature isThe fact is that if in quantum computers we choose a platform that is most effectively suitable for solving certain problems, then with the exchange of quantum information everything is obvious: photons, that is, particles of light, do the best job. There are practically no alternatives. Therefore, researchers are already aware of what the element base will be. The only difficulty is that quantum information, which arises, for example, as part of the operation of a superconducting quantum computer, is somehow translated into a photon that can be transmitted over long distances. And then convert it again into the form that is accessible to a quantum computer. If quantum cryptography is a clear technological front that is at a very high stage of readiness, then the field of quantum communications associated with the exchange of quantum information between quantum computers is a big task that is at a fairly early stage.
While in quantum computing it is common practicetalking about quantum volume - increasing the number of qubits and the accuracy of operations, in quantum communications in a broad context there is not yet a single metric. In quantum cryptography, scientists focus on the rate of key generation over any distance. Most often, the key generation speed of 50 km is considered, which allows you to compare different devices. Sometimes they also study some limiting characteristics, for example, the maximum distance for generating keys.
Railway quanta
There are several areas around the rail transport system where quantum communications (including cryptography) could be useful.
First of all, this is a story about fiber opticcables. Fiber optic cable is one of the main tools for transmitting quantum information. In quantum cryptography, we use it to transmit photons that form cryptographic keys.
Secondly, the railway infrastructure itself -a set of complex technical objects that must be protected. Ideally, if we had a quantum distribution of keys along railway lines, we could use these quantum keys to solve information security problems arising in the railway industry.
And, finally, many railway routes -not only the transport of people, but also the transport of a large amount of various data. For example, Moscow - Petersburg, one of the flagship projects of Russian Railways. The value of the route is obvious: there is a colossal number of data users in Moscow and no less number in St. Petersburg. They exchange a large amount of meaningful information that needs to be protected, so the idea of using quantum cryptography is without a doubt economically justified.
Usually the implementation of quantum distributionkeys between two points A and B, located at a distance of more than a hundred kilometers, is carried out by adding additional intermediate trusted nodes on the route from A to B. Such a network is called a "backbone" (in English. backbone - "Hi-tech"). A ring structure is also possible in the world: when a part of a ring fails, information can be sent to another part of the ring. With a star system design, the central office and the peripheral architecture work - they are suitable for a distributed architecture. There can be closed and open structures, ramified, like the Beijing-Shanghai network, this is a kind of "backbone" with a set of long-distance networks.
Quantum and post-quantum cryptography
Не стоит считать, что криптография — exclusively for companies in the financial or banking sector, it concerns everyone. We all have to exchange data in encrypted form, because some of the information we use is actually of high value. For example, we want to make a purchase on the Internet using a credit card. To do this, we need to somehow transfer the credit card details to the bank, but so that the bank can write off the money, but the attacker does not.
The cryptography paradigm is based on the fact that the methodtransformation is known to the attacker. That is, he knows how we encrypt, but he does not know the only secret encryption parameter - the cryptographic key. This means that in order to implement the encryption cycle, we need to somehow exchange a cryptographic key with the recipient of the information.
How can I transfer keys?To solve this problem, special couriers were used at the state and company level. The method is partially implemented to this day - for example, by diplomats. The disadvantages of this approach are obvious: it is complex, not economically feasible, and is functionally suitable only for a very small number of operations—you won’t be able to buy a book on the Internet this way.
Somewhere in the mid-70s and 80s a newconcept is public key cryptography. The idea is that we can generate a cryptographic key by implementing some set of mathematical procedures. So, we, legitimate users, will only need to perform efficient mathematical operations, such as multiplying numbers. And in order for attackers to gain access to our keys, they will need to implement a complex operation - for example, factoring numbers into prime factors.
This concept still works great today, butAt some point, it became clear that the moment a sufficiently powerful quantum computer appeared, the current generation of algorithms, built on problems such as factoring numbers into prime factors, would cease to be stable. New means of generating cryptographic keys will be needed, since the main vulnerable element of cryptography with the advent of a quantum computer will be key distribution and digital signatures.
There are two fundamentally new approaches tosolving the problem. The first is quantum cryptography, that is, quantum key distribution (which we described earlier). Quantum cryptography works like this: we encode bits of information into single quantum states of light (photon) and transmit them. By the level of errors in transmission, you can immediately determine the degree of intrusion of intruders. If the error rate does not exceed a certain threshold, we say that we can shorten our keys in a special way so that the interceptor information about the shortened keys is negligible. This procedure is called "hardening" and is necessary to obtain the final secret keys.
Thus, we solve the problem of distributioncryptographic keys if intruders have a quantum computer, since quantum cryptography cannot be broken with a quantum computer. Benefits: Fundamental, physics-based security. Disadvantages: restrictions on distance, cost and speed of key generation. It is also important to note that quantum key distribution systems are complex hardware and software systems. Despite the fact that the security of quantum-generated keys is proved on the basis of the axioms of quantum mechanics, there is always a danger of vulnerabilities in a specific physical implementation.
Второй подход — постквантовая криптография — идея creation of new asymmetric cryptographic algorithms, built not on the problems of decomposing numbers into prime factors, but on other complex mathematical problems, in the solution of which a quantum computer will have no advantages. For example, searching for a collision of a hash function. It turns out that if we build the signature or distribution of keys on such, as they say, post-quantum primitives, we can defend ourselves against attacks using a quantum computer.
Post-quantum cryptography is sufficient todaywell developed: commercial libraries, solutions, products are already presented. Now the technology is going through the stage of standardization: both in Russia and in the world there is a process of deciding which solutions will be standardized. I think that on the horizon of 2024 the standards will be fixed. Advantages of the technology: simplicity and high speed of integration (since we are talking about software), regular software updates. Already today, such solutions are used to strengthen the protection of valuable data of a wide range of services and applications of corporate users and individuals (web, mobile and desktop applications). The main disadvantage is that the secrecy of post-quantum cryptography is still based on some assumptions about the difficulty of solving certain classes of mathematical problems. There is always some hypothetical probability that a “post-quantum” computer will appear, with which it will be possible to hack post-quantum algorithms. Unlike quantum key distribution. There is no fundamentally provable strength here - such algorithms continue to be studied from the point of view of their strength.
It is worth noting that these two technologies can bevery well combined. Thus, highly loaded backbone data transmission channels between, for example, data centers of large companies can be protected using quantum cryptography. And our correspondence or a bank transaction for a thousand rubles is done using post-quantum cryptography. That is, quantum and post-quantum cryptography should not be opposed, but productively think of them as synergistic technologies. It's just that one is more focused on the stack layer related to the infrastructure, and the other is related to the user.
The quantum cryptography standard is alsois being formed. The standard will be a specific protocol, that is, a specific method of what quantum state needs to be taken, how to prepare and measure it, and what to do with it next. So far there is one candidate for standards - the BB84 protocol with deceptive states. This protocol guarantees secret key generation. But new protocols appear constantly.
Quantum blockchain and startups
In recent years, much attention has been paid toblockchain technologies - technologies for managing distributed databases. Blockchains use two important cryptographic tools. First, electronic signatures to confirm the authorship of transactions that we want to send to blocks. Secondly, a variety of methods for achieving consensus. For example, one of the methods, proof of work (in English, proof-of-work - “High-Tech”), is based on cryptographic hash functions.
Blockchain is vulnerable against a quantum computer inparticularly if electronic signatures and consensus mechanisms are used, which are not resistant to quantum computer attacks. However, it is possible to create blockchains that are resistant to such attacks—quantum-secure (quantum) blockchains. Quantum blockchain uses either quantum or post-quantum cryptography (or a combination of them) and allows signatures and consensus to be made more resistant to a quantum computer.
При условии интереса российских пользователей we can expect the emergence of a quantum blockchain in the country in the future two to three years. Initially, it is necessary to create an infrastructure of quantum communication networks, on which a distributed system will be created in the future.
Квантовые коммуникации — наиболее популярное direction for the work of Russian startups. Several divisions of large companies, vendors of classical information security, operate on the market. These are startups based on ITMO University, Quanttelecom, divisions of companies specializing in information security, InfoTeKS and Cryptosoft. QRate is a spin-off of the Russian Quantum Center since 2017. Startups are more likely to work with grants and private investment. Venture deals in Russia are still unknown to me.
Internet of Things and Quantum Security
Many Internet of Things devices - sensors -can be both classical and quantum. Let's say we have a set of classic sensors, Internet of Things devices, control gateways that have confidential information. To connect them together, you need a cryptographic protection protocol - again, quantum communications.
In this direction, so far there are onlyprototypes that protect individual elements or devices - it’s too early to talk about industrial scale. First, the world needs to understand the value of the direction, select the Internet of Things device that needs protection and effectively implement quantum communication. In addition, a number of technical barriers need to be overcome.
Today it is not entirely clear what exactly is inThe Internet of Things needs to be protected at such a high level. However, as Internet of Things technology spreads, so will the value of information and the value of hacking it. In theory, hacking can be especially dangerous in fully automated production. Thus, if sensors transmit incorrect information to the decision-making center, decisions will be made incorrectly, and the economic damage from such an attack can be quite significant.
Five Industries Where Quantum Communications Will Be Applied Soon
- Finance.Banks are the first adopters of new technologies.
- Public sector.Here, communications are related to user data, government systems, elections, that is, all areas in which a high level of protection is important.
- Telecommunications.Remote information storage services (good protection is also important for them). Data for storage can be encrypted using a quantum method.
- Medicine.The world is collecting more and more genetic data,which determine the whole life of a person and its features. In a number of countries, a process is already underway to give legal force to a part of a person's genetic data, equating it with passport data. It is also important to protect them from attacks and manipulation.
- Energy.It is important to protect the management of large infrastructure, automation systems, and energy transmission. Cryptography is already used at many points in such systems.
Quantum communications in the world and in Russia
Quantum communications around the world have become part ofnational programs on quantum technologies. Experts consider China to be the world leader, but communications are also actively developing in the European Union. The Japanese company Toshiba maintains a laboratory in Cambridge, several projects are working in the UK and in the USA (but the latter are still more focused on quantum computing).
The sphere of quantum communications in Russia looks likeinvestment attractive. The technological level of Russian quantum cryptography today is comparable to the global one, and some solutions for the post-processing of keys look better than their world counterparts.
Like any fairly young technology,Quantum communications have certain difficulties with widespread development. Until there is a precedent in the world with hacking or theft of any valuable information using a quantum computer, quantum encryption looks more like insurance. People do not understand whether its potential is being fully realized, which in turn makes it difficult to attract investment. To prove potential, you need at least one hack. Also, to reveal it, the Russian market lacks projects like a road map; mass production of devices and attempts to improve them.
Not all companies openly share data on whetherwhat stage of development are their solutions. QRate has a finished product ready for industrial use, it is being tested by potential clients - for example, Gazprombank. Sber also tested the company's systems for fault tolerance for a year. The startup is developing quantum communication technology with a focus on fiber optic implementation.
Construction started in December 2020the main quantum network Moscow - St. Petersburg by Russian Railways. This is a line that will consist of segments at a distance of 100-200 km. They are needed to reduce losses in signal transmission, re-encryption of the signal at the nodes. Classical trusted nodes in the network are used because quantum repeaters are not yet sufficiently developed (another of the big scientific problems). In general, this network is an example of an economically viable project in the field of quantum communications with a large amount of data circulating between Moscow and St. Petersburg. The network will help, among other things, to protect the communication channels through which unmanned Sapsans and Swallows will be controlled.
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