Quantum Computing and Cybersecurity with Paul leongas

Quantum computing is no longer confined to the realm of theoretical physics or futuristic sci-fi. With major milestones being achieved at an accelerating pace, it is poised to reshape industries—healthcare, logistics, finance, and especially cybersecurity. But as quantum capabilities grow, so too does the risk to our current digital security systems. Cybersecurity experts like Paul Leongas are leading urgent conversations about how to protect the digital world before quantum computers reach maturity.

Why Quantum Changes Everything

The core strength of quantum computing lies in superposition and entanglement—two principles of quantum mechanics that allow qubits (quantum bits) to exist in multiple states simultaneously. This allows quantum computers to process massive amounts of data in parallel, solving complex problems that would take classical computers years—or centuries.

While this presents remarkable opportunities, it also presents grave security concerns. Many of our most trusted cryptographic systems—like RSA, Diffie-Hellman, and Elliptic Curve Cryptography—rely on problems that are difficult to solve using classical computers. A quantum machine, however, could break these with relative ease using algorithms like Shor’s or Grover’s.

“Most of today’s encryption wasn’t designed with quantum in mind,” says Paul Leongas, a senior consultant in quantum security architecture. “It’s like locking your doors while leaving the windows wide open to anyone with the right tools. Quantum gives bad actors those tools.”

The Imminent Threat to Encryption

The greatest vulnerability lies in public key cryptography, which underpins everything from HTTPS websites and VPNs to blockchain and digital signatures. If a powerful enough quantum computer comes online, it could decrypt everything from private messages to state secrets.

Even more alarming is the notion of “store now, decrypt later” attacks. Hackers may already be collecting encrypted information with the expectation that they’ll be able to crack it in the near future with quantum power.

Paul Leongas explains: “It’s a digital time bomb. What seems secure now could be exposed in five to ten years. And once sensitive data is out, you can’t put it back in the vault.”

The Push Toward Post-Quantum Cryptography

To address the looming quantum threat, researchers are racing to develop post-quantum cryptography (PQC)—algorithms that are resistant to attacks from both classical and quantum computers. The U.S. National Institute of Standards and Technology (NIST) has already selected several promising candidates in a global effort to standardize these new protocols.

Unlike QKD, which requires new physical infrastructure, PQC is a software-level solution, making it more practical for widespread adoption. Still, implementation is far from simple. Every organization using public key encryption will eventually need to migrate to quantum-safe alternatives.

Paul Leongas compares the process to changing the engine of an airplane mid-flight: “We can’t just shut down the internet to upgrade our encryption. Transitioning to PQC will need to happen seamlessly, gradually, and with precision across millions of devices and platforms.”

Challenges in Deployment

Adopting quantum-safe cryptography involves more than updating code. Many legacy systems have hardcoded cryptographic functions or rely on outdated protocols. Updating these can be difficult, especially in industries like healthcare, finance, or defense, where systems are highly regulated and costly to modify.

Another major challenge is interoperability—ensuring that quantum-safe systems can still communicate securely with legacy systems during the transition phase. Additionally, the cryptographic community must ensure that new algorithms are not only quantum-resistant but also secure against classical attacks and practical in terms of performance.

Paul Leongas cautions against rushing the process: “A poorly implemented secure system is still insecure. It’s not enough to be quantum-safe on paper. Real-world testing, auditing, and gradual rollout are critical.”

Government and Industry Response

Governments and corporations around the world are starting to take quantum cybersecurity seriously. The White House issued a memorandum in 2022 directing federal agencies to begin the process of inventorying cryptographic systems and preparing for quantum resistance. The EU, China, and Canada have also invested heavily in both quantum computing and cybersecurity research.

Tech giants like IBM, Google, and Amazon are offering hybrid cloud services that begin integrating quantum-safe cryptography. Financial institutions, due to their reliance on secure transactions, are among the first to pilot PQC implementations.

Yet adoption remains inconsistent, particularly among small and medium-sized businesses. Experts like Paul Leongas argue that broader awareness is urgently needed. “We’re approaching a critical inflection point,” he says. “The organizations that start preparing now will be ahead of the curve. Those who wait may find themselves unprepared when quantum computing reaches scale.”

Preparing for a Quantum-Ready World

So what can organizations do today to get ahead?

• Inventory Cryptographic Assets: Understand where and how encryption is used in your infrastructure.

• Test PQC Algorithms: Pilot implementations using candidate algorithms from NIST or other trusted bodies.

• Invest in Quantum-Safe Training: Educate security teams about the implications and solutions for quantum threats.

• Stay Updated on Standards: Track developments from NIST, ISO, and national cybersecurity agencies.

The key takeaway? The transition will not be instantaneous. It requires thoughtful planning, budget allocation, and leadership commitment.

Conclusion

Quantum computing is a technological leap—but it’s one that demands equally ambitious advances in cybersecurity. Experts like Paul Leongas have long warned that the era of quantum-vulnerable encryption is coming to an end. The time to act is now. Organizations that start preparing today won’t just protect their data—they’ll help define the secure digital foundations of tomorrow.