Rethinking Quantum-safe key distribution

Author: Melchior Aelmans

As the threat of quantum computing looms over traditional encryption methods, organizations are exploring quantum-safe alternatives to secure their data. The primary challenge lies in key distribution, how to securely exchange cryptographic keys in a way that is resistant to both classical and quantum attacks.

Two well-known approaches have gained a lot of interest: Post-Quantum Cryptography (PQC) and Quantum Key Distribution (QKD). However, there is a third option that is often overlooked but offers significant advantages: Distributed Symmetric Key Establishment (DSKE). This blog explores why traditional asymmetric cryptography falls short in a post-quantum world, the challenges with existing quantum-safe solutions, and why DSKE presents a compelling alternative.

The problem: Why PKI and asymmetric cryptography fall short

Most modern security frameworks rely on Public Key Infrastructure (PKI) and asymmetric cryptography (such as RSA and ECC) for secure key exchange. However, these methods are fundamentally vulnerable to quantum computers due to Shor’s algorithm, which can efficiently break RSA and ECC encryption. As quantum computing advances, organizations must transition to new cryptographic approaches to ensure long-term security.

The challenges with existing Quantum-safe solutions

1. Post-Quantum Cryptography (PQC)

PQC algorithms aim to replace RSA and ECC with cryptographic schemes resistant to quantum attacks. However, they come with challenges:

• Mathematical assumptions: PQC algorithms rely on complex mathematical problems that are currently believed to be hard to be solved for both classical and quantum computers. But history has shown that mathematical breakthroughs can render cryptographic schemes obsolete overnight.
• Performance overhead: PQC algorithms are significantly more demanding in terms of computation and memory. Their codebases are, on average, 50% larger than classical asymmetric algorithms, and key sizes can be orders of magnitude larger, making them impractical for lightweight devices such as IoT sensors.
• Complexity: The increased codebase could considerably increase the attack surface as more code means more room for implementation errors and side-channel attacks.

2. Quantum Key Distribution (QKD)

QKD is another approach which leverages the principles of quantum mechanics to securely distribute encryption keys. Although QKD technology is evolving fast there are important limitations today:

• Infrastructure Requirements: QKD requires specialized hardware and fiber-optic networks or satellite links, making it costly and complex to deploy at scale.
• Distance Limitations: Current QKD implementations are constrained by distance, requiring trusted relay nodes that introduce security risks.
• Authentication: QKD channels rely on an authenticated classical channel, typically secured using a pre-shared key, which in turn necessitates a separate key distribution system independent of the QKD channel itself.

The third option: Distributed Symmetric Key Establishment (DSKE)

DSKE offers an alternative that provides strong quantum-safe security without relying on quantum hardware. Instead, it is based on information-theoretic security, meaning that its security does not depend on the difficulty of solving mathematical problems but on (physical) distribution methods that are fundamentally secure.

How DSKE Works

DSKE leverages a distributed approach to key establishment by securely synchronizing the creation of keys between multiple endpoints. Instead of relying on public-key cryptography, it uses pre-shared secrets, physical and network-based entropy distribution, and authenticated key synchronization protocols to establish cryptographic keys securely. This ensures that even if an attacker intercepts communications, they cannot reconstruct the keys.

DSKE also provides forward secrecy and resilience against both classical and quantum adversaries, as key material is frequently refreshed and never actually exchanged, communication flows through secure channels and the system works without reliance on computational hardness assumptions. This makes DSKE particularly well-suited for high-security environments, IoT networks, and large-scale infrastructure deployments where performance and security must be balanced.

Why DSKE is a game-changer

• Mathematically unbreakable: Unlike PQC, DSKE does not rely on computational hardness assumptions, making it resistant to both classical and quantum attacks.
• Lightweight and efficient: DSKE is computationally efficient and does not require the large key sizes associated with PQC, making it ideal for resource-constrained environments like IoT and embedded systems.
• No special hardware required: Unlike QKD, DSKE can operate over existing network infrastructure, reducing deployment costs and complexity.
• Regulatory alignment: Many cybersecurity regulations, including the White House directives, and the position paper from BSI and AIVD, emphasize the need for quantum-safe key distribution. DSKE provides a practical and compliant alternative that enterprises can start evaluating today.
• Standardisation ongoing in the Internet Engineering Task Force

Preparing for a Quantum-Safe Future

As enterprises and governments assess their quantum resilience, it is crucial to recognize that there is no single answer to quantum-safe key distribution. Organizations should evaluate their current security landscape and map out which quantum-safe solutions align with their operational needs. DSKE presents a viable option that can complement or even replace existing approaches in many scenarios.

Final Thoughts

Quantum Bridge is at the forefront of quantum-safe key distribution solutions innovation, helping organizations transition to a quantum-safe future without the limitations of PQC and QKD. Now is the time to assess your security posture and plan your quantum-safe roadmap.

Are you ready to explore DSKE as part of your quantum-safe strategy? Start by analyzing your current security landscape and evaluating how DSKE can enhance your defenses. 

Ready to dive deeper? Reach out to our experts.