The quantum threat explained
Understanding why today's cryptography is at risk — and what you can do about it right now.
Why quantum computers threaten today's cryptography
Two quantum algorithms — discovered decades ago — are capable of breaking the cryptographic foundations that secure virtually all digital communications today.
Grover's Algorithm
Threat to symmetric cryptography
Target: Symmetric Cryptography (AES)
Grover's algorithm effectively halves the security strength of symmetric encryption. A 256-bit AES key becomes as secure as a 128-bit key in the quantum era — significantly reducing the effort required to brute-force encrypted data.
Impact: Organisations must double their symmetric key lengths (e.g., move from AES-128 to AES-256) to maintain equivalent security against quantum adversaries.
Shor's Algorithm
Threat to asymmetric cryptography
Target: Asymmetric Cryptography (RSA, ECC)
Shor's algorithm completely breaks asymmetric encryption by enabling attackers to derive private keys from public keys — rendering RSA and ECC fundamentally insecure. This affects HTTPS, digital signatures, email encryption, and more.
Impact: No key length increase can fix this. RSA and ECC must be replaced entirely with NIST-approved post-quantum algorithms (ML-KEM, ML-DSA, SLH-DSA).
Harvest Now, Decrypt Later (HNDL)
Nation-state adversaries don't need a quantum computer today to start attacking your data. They are harvesting encrypted traffic right now and storing it for when quantum computers become powerful enough to decrypt it.
This strategy is particularly effective against data with long-term sensitivity: government secrets, financial records, medical data, intellectual property, and private communications.
The consequence is that even data encrypted today with the strongest classical algorithms may be exposed in the future. The window to act is now — before your most sensitive data becomes retroactively vulnerable.
How HNDL works
Intercept
Adversary captures and stores your encrypted network traffic — today, using classical computers.
Store
Encrypted data is stored in large-scale archives, waiting for the quantum era.
Decrypt
Once a sufficiently powerful quantum computer exists, all stored data is decrypted using Shor's algorithm.
The harvesting is happening right now — the threat is not theoretical.
The future is quantum-safe
Quantum computing won't arrive overnight — but when it does, cryptography must already be ready. A full migration of critical infrastructure takes 2 to 5 years. Cryptography is embedded in thousands of systems. Most enterprises don't even know where.
Today
HNDL attacks are in progress. NIST standards have been finalised. Start your inventory now.
2025–2028
Regulatory deadlines in EU, UK, and CH require discovery and migration planning to be underway.
2030+
High-risk migrations must be complete. Quantum computers may reach sufficient capability.
The platform built for this transition
Unmatched scope and automation
QComply leads in depth of cryptographic discovery and automated scanning across hybrid environments.
Use your existing agent infrastructure
Deploy QComply using your existing agent infrastructure for fast, frictionless rollout — no rip and replace.
Predictable fixed cost
Unlimited service at a fixed price. No per-asset billing, no surprises — just complete coverage.
Multi-jurisdiction compliance reporting
Quantum-safe compliance reporting for EU, Switzerland, and the UK — from one integrated platform.
Read our EU compliance overview
A detailed guide to PQC regulatory requirements in the European Union.
Read EU Compliance Overview ↗Ready to make your organisation quantum-safe?
With QComply, your organisation gains the tools to discover, assess, and migrate at scale — ensuring your data stays protected in the post-quantum world.