Quantum computing is no longer a far-fetched scenario. Governments and tech giants are racing to build machines that could render current cryptographic systems obsolete. The threat is real and it’s already begun.
This article walks you through a practical, technical approach to Post-Quantum Cryptography (PQC), including performance benchmarks, hybrid stacks, and a migration readiness calculator.
Why It Matters: “Harvest Now, Decrypt Later”
Even if quantum computers can’t break encryption today, attackers are already stockpiling encrypted data with plans to decrypt it in the future.
This strategy Harvest Now, Decrypt Later is already being used. That means the urgency isn’t theoretical anymore.
NIST Finalists: The New PQC Standards
NIST has selected several algorithms for post-quantum cryptography:
- ML-KEM (key encapsulation, based on Kyber)
- ML-DSA and SLH-DSA (digital signatures)
These will define future standards for cryptographic safety in TLS, VPNs, and secure messaging protocols.
Real-World Benchmark: RSA-2048 vs ML-KEM-768
| Operation | RSA-2048 | ML-KEM-768 | Overhead |
|---|---|---|---|
| Keygen | 84ms | 0.05ms | 0.0006x |
| Encapsulation | 0.08ms | 0.07ms | 0.875x |
| Decapsulation | 2.4ms | 0.08ms | 0.033x |
| Public Key Size | 256 bytes | 1,184 bytes | 4.6x |
| Ciphertext Size | 256 bytes | 1,088 bytes | 4.25x |
Key insight: ML-KEM is faster and more efficient for computation but larger in size. For most systems, the performance gain is worth the storage tradeoff.
Using Hybrid Cryptographic Stacks
Many cloud providers and browsers now support hybrid key exchanges. This means combining post-quantum and classical algorithms in the same handshake—for example:
- X25519 + ML-KEM
- RSA + ML-DSA
This ensures backward compatibility while adding quantum resistance.
Interface-Level Readiness
For engineers and architects, building cryptographic agility means thinking in versioned APIs, migratable keys, and algorithm-aware interfaces.
PQC isn’t a drop-in replacement. You need systems that can:
- detect algorithm versions
- upgrade encrypted keys
- monitor post-quantum security status
Try the PQC Migration Calculator
Not sure how ready your organization is for PQC?
This tool will calculate your estimated migration timeline based on:
- Infrastructure scale
- Primary cryptographic use
- Data sensitivity
- Current readiness
- Technical constraints
Conclusion: The Clock Is Ticking
After 18 months of diving into post-quantum crypto, one thing is clear:
We're not waiting for quantum computers. We're racing adversaries who already are.
The organizations that survive won’t be the biggest or richest. They’ll be the ones who prepared early, stayed agile, and treated cryptography as a living system not a frozen dependency.
Full article + visuals:
https://ncse.info/post-quantum-cryptography/
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