Understanding the Solutions for Quantum Threat

This note is part of a series of brief discussions addressing the most common and important questions we encounter around quantum-safe migration, as highlighted in the article, "What's Your Most Important Question When It Comes to Quantum Safe Migration?"

In this installment, I focus on the question, "What solutions are available to mitigate the quantum threat? Are there any recommendations or guidelines?"

The Role of Cryptography in Security

Cryptography plays a vital role in securing digital communication, data, and systems by providing essential security features such as confidentiality, integrity, authentication, and non-repudiation. It protects sensitive information through encryption, ensuring that only authorized parties can access data, and cryptographic hashes verify data integrity. Authentication and digital identity rely on cryptographic methods, such as digital certificates and multi-factor authentication, to verify users and devices. Cryptography also enables secure communication over untrusted networks, such as the internet and wireless channels, through protocols like TLS/SSL. Digital signatures provide authenticity and prevent denial of involvement in transactions. Overall, cryptography is the backbone of trust and security across industries and applications.

The Quantum Threat

However, as quantum computers advance, they will be capable of breaking the cryptographic systems that currently safeguard sensitive information, including financial data, intellectual property, personal information, and national security secrets. These systems rely on mathematical problems like integer factorization and discrete logarithms, which are difficult for classical computers but relatively easy for sufficiently powerful quantum computers. This breakthrough could have devastating consequences for individuals, businesses, and governments.

There are two primary solutions to mitigate quantum threats focusing on upgrading cryptographic infrastructure to quantum-safe alternatives - Post Quantum Cryptography (PQC) and Quantum Key Distribution (QKD).

Post-Quantum Cryptography (PQC)

Post-Quantum Cryptography (PQC) focuses on developing algorithms resistant to attacks from both quantum and classical computers. These algorithms are expected to be computationally intractable for quantum computers, efficient enough for practical real-world applications, and capable of providing strong security against both known and potential quantum attacks. PQC algorithms still operate within the classical binary world.

To facilitate this transition, the National Institute of Standards and Technology (NIST) conducted a multi-year standardization process to select PQC algorithms for widespread adoption. This process involved several rounds of public evaluation and feedback from the global cryptographic community. NIST considered specific classes of algorithms that are expected to offer strong resistance to quantum attacks:

• Lattice-based cryptography: Built on solving problems related to lattices—multi-dimensional grids of points—this is one of the most promising areas of PQC.

• Hash-based cryptography: Relies on the security of cryptographic hash functions. It is one of the simplest forms of PQC and has been extensively studied for decades.

• Code-based cryptography: Based on the difficulty of decoding general linear codes, this method is resistant to quantum and classical attacks, though its large public key size is a drawback.

• Multivariate cryptography: Relies on the difficulty of solving systems of multivariate polynomial equations over finite fields. While secure, it has not gained as much traction as other PQC methods.

• Isogeny-based cryptography: A more recent approach that depends on the difficulty of finding isogenies (mappings) between elliptic curves.

In August 2024, NIST published the first batch of PQC algorithm specifications: ML-KEM FIPS 203 (CRYSTALS-KYBER), ML-DSA FIPS 204 (CRYSTALS-Dilithium), and SLH-DSA FIPS 205 (SPHINCS+).

PQC represents the next frontier in securing our digital world against quantum computing threats. By transitioning to PQC algorithms, organizations can protect sensitive data and communications from future quantum attacks. However, the shift to PQC requires careful planning, from performing quantum risk assessment, conducting cryptographic inventories to adopting hybrid solutions that ensure secure operations during and after the transition. Embracing PQC now allows organizations to stay ahead of quantum threats and maintain trust in their security systems into the future.

Quantum Key Distribution (QKD)

Quantum Key Distribution (QKD) is a cryptographic technique that uses the principles of quantum mechanics to establish a secure communication channel between two parties. Unlike classical cryptography, which relies on mathematically complex problems, QKD leverages the fundamental properties of quantum particles to guarantee the security of transmitted information.

The key principles of QKD include:

• Quantum Entanglement: Pairs of quantum particles can become entangled, meaning the state of one particle instantaneously affects the state of the other, regardless of the distance between them.

• Uncertainty Principle: According to Heisenberg's Uncertainty Principle, it is impossible to measure the properties of a quantum particle without disturbing its state.

Any attempt to intercept or measure these quantum particles will disturb their state, alerting the communicating parties to potential eavesdroppers. QKD provides unconditional security, meaning the security of the key is not dependent on the eavesdropper’s computational power. The BB84 protocol, proposed by Charles Bennett and Gilles Brassard in 1984, is the most well-known QKD protocol, though many others have since been developed.

As we approach the era of quantum computing, QKD could be crucial for ensuring the security of our most critical communications. The future of secure communication lies in the quantum realm, with QKD leading this transformation.

Challenges in Adopting Quantum-Safe Solutions

Despite the availability of solutions to address quantum threats, there are challenges in adopting both PQC and QKD.

Challenges with PQC:

• Performance: PQC algorithms have different profiles compared to classical algorithms and also among themselves. They often require more computational resources and larger key sizes than classical systems.

• Interoperability: Ensuring compatibility between PQC algorithms and existing systems can be complex, especially in global distributed infrastructures like the internet or blockchain networks.

• Evolving Standards: The NIST PQC competition has made strides toward standardizing quantum-resistant algorithms, but widespread adoption across industries and systems will take time as standards across other areas of security protocols and industries are yet to be completed.

• Long-Term Viability: While PQC algorithms are designed to withstand quantum attacks, advancements in quantum computing could eventually challenge some of these algorithms. Ongoing research is essential.

Challenges with QKD:

Despite its theoretical advantages, QKD faces several practical challenges that limit its widespread adoption in the current situation:

• Distance Limitations: Quantum states degrade over long distances, limiting the range of QKD. While quantum repeaters are being developed, they are not yet commercially viable.

• Infrastructure Costs: Implementing QKD requires dedicated quantum communication infrastructure, which can be expensive.

• Complex Implementation: QKD systems require precise control over quantum states, making them technically challenging to implement and maintain.

• Lack of Peer Authentication: QKD still relies on classical mechanisms to authenticate communicating parties, such as pre-shared keys or post-quantum signature schemes.

Guidelines and recommendations from Cybersecurity Agencies

Every organization is very keen to ensure they have right solutions protecting their digital systems against quantum threat and the solutions are compliant to industry standards and guidelines. Below are key guidelines from various national cybersecurity agencies:

• Guidelines from US National Security Agency/Central Security Service: The NSA views quantum-resistant cryptography (PQC) as a more cost-effective and easily maintained solution than QKD, stating that it does not support QKD for protecting National Security Systems.

• Position of UK’s National Cyber Security Centre : The NCSC cautions against the use of QKD for government or military applications and advises against sole reliance on QKD for business-critical networks, especially in Critical National Infrastructure sectors.

• A Joint Position Paper on Quantum Key Distribution by French Cybersecurity Agency (ANSSI), Federal Office for Information Security (BSI), Netherlands National Communications Security Agency (NLNCSA) and Swedish National Communications Security Authority, Swedish Armed Forces: Agencies from France, Germany, the Netherlands, and Sweden state that QKD is not yet mature enough for widespread use and recommend prioritizing the quantum safe migration with PQC.

• European Commission Recommendation on a Coordinated Implementation Roadmap for the transition to Post-Quantum Cryptography: Encourages Member States to adopt a coordinated strategy for transitioning to PQC, including hybrid schemes that combine PQC with existing cryptographic approaches or QKD.

Cybersecurity agencies across the U.S., UK, and Europe recommend PQC as the most immediate solution for quantum-safe cryptography. However, as the technology matures, hybrid solutions combining PQC and QKD could become part of a layered defense strategy or defense in depth strategy, offering greater quantum resilience. Many organizations in banking, telecom, space, and defense sectors are already exploring both solutions. In addition, research into QKD remains vital for long-term quantum communications and the development of the quantum internet.

Conclusion:

As the quantum computing era approaches, the urgency to secure our digital infrastructure grows. Both Post-Quantum Cryptography (PQC) and Quantum Key Distribution (QKD) offer robust solutions to safeguard against quantum threats, but each comes with its own set of challenges. While PQC provides a more immediate and practical solution, especially with the recent NIST standardization of quantum-resistant algorithms, QKD represents a glimpse into the future of secure communications, driven by the unique principles of quantum mechanics.

Cybersecurity agencies globally advise organizations to prioritize PQC in the short term, while keeping an eye on the evolving landscape of quantum security solutions. While PQC is ready for adoption today, ongoing research in QKD and its future integration with PQC could enhance security in the quantum age. By taking proactive steps now, businesses, governments, and individuals can ensure that their data and systems remain secure in a post-quantum world.

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