The division of physics that explains the behavior of extremely small objects, on the scale of atoms and subatomic particles is referred to as quantum physics. Matters at the quantum level work very differently than at our scale of interaction in our day to day lives. Quantum physics gives rise to some useful and amazing properties that quantum technology exploits. I will only briefly describe three of those properties here.
Superposition
Classical bits possess many more quantum properties than do quantum bits. The classical bit is represented by a single amount of information: it has value zero, or value one. Qubits are either a zero or one or any combination of these two values. A quantum bit in a mixture of zero and one is said to be in a combination of its two values. Since the qubits can be a zero and one at the same time, the quantum computers can then perform multiple calculations simultaneously. This makes it possible to speed up computer performance on numerous challenging problems.
Measurement
Observation or measuring a qubit collapses the qubit into a single value. Eg: You could send me a qubit in a superposition of zero and one, that is, it could be either zero or one or something somewhere in between. Upon the reception of the qubit, I measure the qubit: I check that the qubit is either a zero or one. There is a qubit, which will become 0 with an exact probability (0) or 1 with an exact probability (1) after I measure it, and it will no longer be a mix of these two values. Since the measurement collapses a superposition of a qubit, measurement is essential to quantum security: an eavesdropper who intercepts a quantum message can be detected by measurement. Instead, in a case where you sent me an encryption key via qubits and somebody intercepted that message, the interception will alter that quantum message indicating to us that that encryption key is no longer secure.
Entanglement
The coupling of qubits into each other can be done in a manner that measuring one qubit will alter the state of the other qubit, or even other qubits. This form of coupling is called entanglement. Coupled in this manner, qubits are entangled. What is so amazing about entanglement is that measuring a single qubit will have a direct impact on the state of the qubit or of the qubits that it is entangled to, even when these qubits are many light years apart. Such is the spooky action at a distance that so disturbed Einstein (and many other physicists) in the early early 20th century. A property that quantum technologies are founded on is entanglement. Indicatively, quantum computers would not be able to be quicker than classical computers in lack of entanglement. The key to the exciting uses that quantum technology will unlock – such as efficient drug discovery, cleaner materials science, and discoveries in imaging – is entanglement.
The list of fantastic benefits of quantum technology is extensive; the list of security threats that can be catastrophic and immediate is also extensive.
Our cybersecurity is threatened by the existence of quantum computers. The most well known quantum algorithm is the Shor algorithm, which quantum computers can use to perform some mathematic tasks, including factoring large numbers and computing discrete logarithms, exponentially quicker than would be possible using classical technology. Quantum computers with the ability to run the Shor algorithm will be capable of breaking the asymmetric key algorithms of RSA, DSA and Diffie-Hellman, upon which we base our authentication and key distribution. Cybersecurity depends on authentication and key distribution. In essence, the future quantum computers will make all data transmitted over the Internet susceptible. This will affect all of them; governments, businesses and individuals. Key schemes that are at risk include defensive and military data, intellectual property, financial and medical records and even infrastructure operations such as electricity and water management. One can easily see how catastrophic this can be in case such information is in the wrong hands.
The algorithm that has been used by Shor is nearly 30 years old, and has been found to effectively break such important security schemes. We should only wait before the quantum computing technology will be advanced to execute the Shor algorithm on large inputs. Such quantum computers are expected to be present by the turn of the decade. The day where quantum computers are able to crack these currently-in-use security techniques is sometimes called the Q Day. Q Day is not coming until the end of the decade, but that does not imply that we have until the end of the decade to worry about quantum attacks. There are also Harvest Now Decrypt Later attacks that threaten the information we are transmitting currently. Harvest Now Decrypt Later (HDNL) attacks are attacks where an opponent steals ciphertext data, which cannot be decrypted at present. The opponent stores this cipher-text data until he/she can decrypt it. That in the case of Q Day would be when they get access to a quantum computer with the capability to execute the Shor algorithm. Much of what we currently, and which we will continue to be communicating in the foreseeable future, must be kept secure over long durations of time and even well after the year the year 2030. Due to the current danger of Q Day, and the current danger of Harvest Now Decrypt Later, we must find a counter to this quantum menace as soon as we can.
Techniques that are now being implemented to reduce security vulnerability to quantum threats.
Post Quantum Cryptography (PQC)
As opposed to the currently employed classical security algorithms which will be destroyed by quantum computers, PQC adopts quantum safe classical security algorithms. The new security algorithms are premised on math problems which quantum computers are thought to find difficult to solve. PQC is a strictly classical solution, and can be implemented over the classical internet. This implies that it is relatively fast and simple to apply and due to this is considered a good short-term solution. However, PQC algorithms are not mathematically known to be safe. Quantum or even classical computers may break PQC algorithms in the future. It is not only a hypothetical concern with PQC. Regular classical computers, not even supercomputers, were needed to break two of the most promising PQC algorithms, RAINBOW and SIKE. RAINBOW and SIKE were cracked in less than a weekend and in basically one hour respectively. PQC is dangerous in the long run because its security cannot be proven.
Quantum Key Distribution (QKD)
Quantum Key Distribution, QKD, generally describes prepare-and-measure quantum key distribution protocols functioning on and facilitated by prepare-and-measure networks called QKD networks. It is a physics solution, and is dependent on the laws of superposition and measurement. These quantum properties can always be used to sense the presence of an eavesdropper. Thanks to this fact, you can use quantum information to create a key of which you are certain it has not been intercepted. This is good in theory or on the protocol level. Nonetheless, it has some implementation vulnerabilities like it makes use of trusted relay nodes which makes it less vulnerable in practice. You will require trusted relay nodes to use QKD to distribute a key between nodes that are too far apart. The trusted bit of this term is deceptive. Trusted relay nodes are not trusted nodes, but those that you must trust. Should they be compromised, then your key will be compromised too. Along with extra optical fiber, other resources, including QKD devices, must be deployed to support QKD networks as well. The single purpose in the QKD networks is the key distribution. The best solution would not be vulnerable to implementation, and would possess multi-purpose applications which allow more than key distribution.
Quantum Secure Communication (QSC)
Quantum Secure Communications, QSC, is adopted to describe the entanglement-based security mechanisms that are over and facilitated by the entanglement-based quantum networks. It is a physical solution, which builds on the concept of entanglement. Just as the QKD protocols, you can apply these quantum properties to never miss the presence of an eavesdropper. This quantum information can be used to set up a key of which you are certain has not been intercepted. This work does not only go well in theory or at the protocol level, but also at the implementation level as well. These implementation problems that have plagued QKD can be evaded in the use of entanglement in QSC. Entanglement based quantum teleportation is employed to transmit quantum information to endpoints in the network in QSC, and quantum information is not placed on the network. The quantum networks on which QSC operates are multi-purpose, based on entanglement. It is decades that the QSC security schemes have been around all that needed to happen was the development of the technology to the point where they can actually be utilized. These plans have been experimented and confirmed. The technology is maturing rapidly, entanglement-based quantum networks are appearing everywhere in North America and across the globe. On some of these networks, it has even been possible to test and run QSC.
Hybrid methodology
A common of the offered solutions is the combination of PQC and QSC. PQC will work in the short term, and we will soon require the provable security and value of QSC in the long term. A combination of a hybrid PQC /QSC solution will be as powerful as either solution alone. A hybrid solution is only compromised in case the involved PQC and QSC algorithms are compromised.
Reducing security risks and taking advantage of the merits of quantum technology.
An important and efficient countermeasure against the impending quantum threat is the quantum entanglement-based quantum networks, which provide the concept of quantum network and quantum communication as quantum secure communication (QSC). QSC is safe at least partially due to quantum teleportation, which enables us to transmit quantum information between network users without this quantum information ever being sent on the network. This is because although a centre point of the network can be breached, this will not breach the quantum data.
QSC is an excellent value. The advancements in computing, sensing, and future distributed quantum applications will be possible with the use of the same entanglement-based quantum networks that make this solution possible with the help of the application of the quantum secure communication. QSC can be implemented in the near-term. The security plans are in place and have been tested; the entanglement-based quantum networks capable of executing those plans exist and are currently under construction.
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