Quantum Computing's Cybersecurity Impact: Key Considerations for CISOs -

Quantum computing is moving from theory to reality—and with it comes a serious challenge for today’s encryption systems. For Chief Information Security Officers (CISOs), the threat isn’t in the distant future. It’s already starting to take shape.

The rise of quantum computers capable of breaking modern encryption (known as cryptanalytically relevant quantum computers or CRQCs) could expose sensitive data and secure communications. This threat is often called “Y2Q” or “Q-Day.”

Even though quantum computers can’t yet crack encryption like RSA or ECC, hackers are already collecting encrypted data to decrypt later. This “harvest now, decrypt later” tactic puts long-term secrets at risk.

Why It Matters

Encryption methods like RSA and ECC are based on problems that are hard for classical computers but easy for quantum ones using Shor’s algorithm. Symmetric encryption like AES is safer, but key lengths need to be doubled to stay secure.

The big problem? It can take years to replace current cryptographic systems with quantum-resistant alternatives. That’s why it’s crucial to start planning now.

A helpful concept here is Mosca’s Theorem: if the lifetime of your data + time needed to upgrade encryption > the time until quantum computers arrive, you’re vulnerable.

What CISOs Should Do Now

1. Assess Quantum Risks:
Identify where your organization uses public-key cryptography. Focus on the systems that handle the most sensitive and long-lasting data.

2. Build Crypto-Agility:
Design systems that can switch encryption methods easily. Crypto-agility helps your business adapt quickly as new algorithms are approved.

3. Follow NIST Standards:
NIST is finalizing post-quantum cryptography (PQC) standards, including algorithms like CRYSTALS-Kyber and CRYSTALS-Dilithium. Start testing these now in non-production environments.

4. Educate Leadership:
Help executives understand that quantum threats are real—and that acting early is a competitive advantage. Frame it as a long-term business risk, not just a technical one.

5. Strengthen Your Architecture:
Use network segmentation and zero-trust models to reduce your attack surface. These practices boost your defenses even before quantum threats become widespread.

Transitioning to Post-Quantum Security

Migrating to PQC is more complex than past cryptographic changes. It affects digital signatures, secure communications, and identity systems across your organization. PQC algorithms often need larger key sizes and more processing power—especially challenging for legacy systems.

To manage this, consider a hybrid approach. Use both traditional and post-quantum algorithms during the transition. This protects you now and prepares you for the future.

Strategic Focus Areas

Create a Migration Roadmap:
Start with the most critical cryptographic assets and build a phased, risk-based plan. Align it with tech refresh cycles to spread out costs and efforts.
Explore Quantum as a Defense Tool:
Quantum tech isn’t just a threat—it’s also an opportunity. For example, quantum random number generators improve encryption, and quantum machine learning can boost threat detection.

The shift to quantum-safe security is one of the biggest transformations in cybersecurity history. It will take vision, coordination, and early action. CISOs who start today will protect their organizations tomorrow—ensuring resilience in the age of quantum computing.