Cybersecurity's New Quantum Shift: When Cryptographers Team Up Against Tomorrow's Qubits

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Benjamin David investigates the recent world-first commercial trial of a quantum secured metro network and what this means for cybersecurity.

Quantum technology heralds a new era for businesses, promising to revolutionize various sectors, from aviation and data analytics to medical research. How quantum technology will impact cybersecurity, however, has attracted a lot of attention in recent years, with advanced cryptography often seen as one of the most significant paradigm shifts in the industry. One of the major concerns is that if this technology reaches predicted levels of sophistication, it will likely crack existing encryption algorithms used to secure sensitive data.

Amid the threat posed by quantum computing, groundbreaking quantum technology, such as quantum-secured communication, offers a promising solution. In particular, quantum key distribution (QKD), is oft-advertised as a way to beef up data security. The benefits of this technology are so large that in April 2022, BT, Toshiba and EY announced the launch of a world-first commercial trial of a quantum-secured metro network (QSMN), providing data services secured using QKD and post-quantum cryptography (PQC). But what does this watershed moment mean for cybersecurity?  

Encryption and Q-Day

Almost all internet communications today use public-key cryptography (PKC), also called asymmetric cryptography. PKC enables secure communication at scale. For example, the famous asymmetric algorithm, RSA, is the basis of every secure web session with HTTPS or instant messaging encryption. The principal functions of PKC are key agreement, establishing a shared cryptographic key for secure communication and digital signatures – underpinning proof-of-identity and trust on a network. PKC security is underpinned by how difficult it is to solve mathematical problems of integer factorization and calculating discrete logarithms.

While existing encryption might sound robust, cyber experts have nonetheless admonished business leaders to realize future threats, particularly that said mathematical problems would be easy to solve on a large, general-purpose quantum computer, called cryptographically relevant quantum computer (CRQC). This is because quantum computers operate differently and can perform Shor’s algorithm with prime number factorization in polynomial time. Consider classical computing. The smallest element is a ‘bit,’ which can either be 0 or 1. The quantum equivalent is called a qubit¸ which can also be 0 or 1. However, a ‘qubit’ can also be in superposition – any combination of 0 and 1. A calculation using two bits will necessitate four calculations. Conversely, a quantum computer can do this calculation on all four states simultaneously. By operating using subatomic properties such as superposition, entanglement and interference, quantum computers can scale at an exponential rate.

In cybersecurity circles, they call this possibility ‘Q-day:’ the day when quantum computers will theoretically break the internet. Joseph Carson, chief security scientist and advisory CISO at Delinea, explains that “quantum computing exposes a serious risk to one of the most foundational building blocks of the security industry, and that is encryption since everything in the digital world that we encrypt with a private key today will be possible to decrypt with a quantum computer in the near future.” Just like in the movie Sneakers, we might face a world with no more digital secrets, and whoever has access to quantum computing will be extremely powerful.” Professor Andrew Lord, senior manager of optical research at BT, tells Infosecurity Magazine that the threat from quantum computing will be possible within five years, “and likely to occur within 10 years.”

Cyber experts also point to the fact that threat actors are presently harvesting massive amounts of encrypted data and storing the records until they’re able to break those keys using quantum computing. “Specifically, data which requires long-term security could be at risk of ‘store today, crack later’ attacks,” Professor Lord tells Infosecurity. Brad LaPorte, partner at High Tide Advisors, echoes this concern: “Cyber-criminals and nation-state threat actors may have collected data in a mass scale to be used in the future once quantum-computer technology is available.”

 Trial of a Quantum-Secured Metro Network

The threat from quantum computing will drive the need for cryptography to move beyond the current public key schemes, points out Professor Lord, “towards post-quantum algorithms.” Likewise, LaPorte details that post-quantum connections are required to address the threat from Q-day: “Quantum secure data transmission, including PQC, will aim to make it difficult for quantum computers to break digital signatures.” This is a view echoed by the UK’s National Cyber Security Centre (NCSC), who state in their Preparing for Quantum-Safe Cryptography that “quantum-safe cryptography provides the best mitigation for the quantum computing threat.” Kevin Hughes, senior director at FTI Consulting, explains why post-quantum algorithms (also known as quantum-resistant algorithms) offers a solution to the dangers posed by Q-day: “Quantum physics stipulates that an observation of a quantum state causes a deviation in that state. In quantum cryptography, this means that man-in-the-middle attacks designed to observe the transmitted photons will disrupt the transmission. This disruption will lead to transmission errors, which can be detected and lead to the verification of distributed public keys.”

Despite how promising post-quantum algorithms seem, moving beyond the PKC to post-quantum algorithms is no simple task. LaPorte tells Infosecurity that “many approaches and proposals are being explored to solve the problem that quantum computing is going to introduce.” However, the National Institute of Standards and Technology’s (NIST) Report on Post-Quantum Cryptography (NISTIR 81051) concluded that none of the major proposals are the perfect solution for quantum threats. LaPorte adds: “Nonetheless, NIST recently acknowledged four quantum-resistant encryption algorithms, which might be identified as a potential solution in two years.”

Aware of this need to shift beyond current PKC, BT, Toshiba and EY announced in April this year the launch of a world-first commercial trial of a QSMN. The groundbreaking infrastructure secures the transmission of valuable data and information between multiple physical locations over standard fiber-optic links using QKD. The network’s first commercial customer, EY, will utilize the network to connect two of its sites in London, UK. BT will operate the network and Toshiba will provide QKD hardware and key management software. In the network, QKD keys will be combined with the in-built ethernet security using public-key encryption, which will enable the resultant keys to be used to encrypt the data. The network’s preparation, technical deployment and testing took place in late 2021. This included equipment deployment in racks, adding security systems, resilience testing and running and optimizing the network.

Andrew Shields, head of the quantum technology division, Toshiba Europe, explained how QKD works at the launch: “In quantum communications, each bit is encoded on a single photon. Secrecy can be tested directly because quantum theory dictates that eavesdropping unavoidably alters the encoding of single photons. All of this means that we can detect unauthorized eavesdropping on fiber and distribute secret digital keys that are secure from all future advances in cryptanalysis and computers, even secure from a quantum computer.”

Carson believes that the work by the partnership between BT, Toshiba and EY will ensure that future communication across BT networks will be secure. “The work being done today is so critical as quantum computing is not so far away, and ensuring a stable digital world in a post-quantum computing era is one of the important priorities today,” he explains. “The success of this partnership is tied to the QKD, which is essential in maintaining a high level of trust in the communication security.” Likewise, Hughes states that the trial of a QSMN “marks an enormous leap in cybersecurity [...] the quantum network will afford an enhanced level of security against attacks from quantum computers.” Hughes also highlights other benefits to cybersecurity resulting from the trial, detailing that “it will drive innovation in the cybersecurity industry as more companies start to understand what is possible with quantum cryptography.”

Unsurprisingly, the London network represents a crucial step towards reaching the UK Government’s strategy to become a quantum-enabled economy. The UK Government’s ‘strategic intent’ over the next 10 years aims to make the UK a global center of excellence in quantum science and technology development, the ‘go-to’ place for quantum companies or for global companies to locate their quantum activities and a preferred location for investors and global talent.

Cybersecurity and Quantum-Secured Connection

Many related topics encircle the rollout of quantum-secured connections. One is what this means for cybersecurity, particularly existing cryptography. “The underlying cryptography infrastructure won’t be replaced; quantum communications will supplement the existing infrastructure by adding quantum keys,” Professor Lord tells Infosecurity. “The threat of quantum computers will drive the need for cryptography to move beyond the current public-key schemes towards post-quantum/quantum-resistant algorithms. It still is unclear whether quantum communications will be used across the future network or applied mainly to niche solutions.”

Another important line of inquiry concerns the rollout of quantum-secured connections and whether any country has the infrastructure for a larger rollout of it. Professor Lord explains that the commercial trial of a QSMN currently includes high bandwidth end-to-end encrypted links delivered over BT Openreach’s private fiber networks. “We have journeyed from developing a point-to-point quantum network to building a QSMN, and we are now looking forward to our next step in being a critical player in building a national quantum network,” notes Professor Lord. However, while existing fiber networks could support the larger rollout of quantum-secured connection, “fiber-based quantum communications will not be able to interconnect across oceans, given the distance limitations. Here we expect to see satellite-based quantum communications emerging in the next few years, which could interconnect terrestrial-based quantum regions.”

Yet, despite the promise that fiber-based quantum communications can offer, Professor Lord recognizes the rather perpendicular learning curve: “This is a commercial trial of QKD, so there is a lot still left to explore both in terms of our understanding of the role QKD can play in the broader landscape of securing future networks and in exploring other security technologies like PQC [...] Given that the market for quantum security is still nascent, there is operational learning, technological learning and market learning that needs to happen to address initial challenges and QKD is just a part of the overall system.” Despite this obstacle, Professor Lord is confident that the benefits outway these challenges: “Either way, QKD secured networks will be immune to future evolutions of quantum computers.”

Notwithstanding the challenges, cybersecurity experts appear aligned that the world-first commercial trial of a QSMN marks a critical step forward for cybersecurity. LaPorte tells Infosecurity that the trial is “enabling the global economy by implementing a strategy to become quantum-enabled and all of the benefits that come with it but in a more secure manner.” Although this is a great start, he concludes, “we are still many years away from solving this problem. The world will be watching closely.”

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