Post-Quantum Cryptography Guide

Quantum computers will eventually break RSA and ECC encryption. Post-quantum cryptography (PQC) provides quantum-resistant alternatives. The migration has already begun.

Why Act Now?

The threat model is "harvest now, decrypt later" — adversaries collect encrypted data today, planning to decrypt it once quantum computers are powerful enough. If your data has a long shelf life, you need PQC now.

NIST finalized its first PQC standards in 2024:

• ML-KEM (Kyber) — key encapsulation
• ML-DSA (Dilithium) — digital signatures
• SLH-DSA (SPHINCS+) — stateless hash-based signatures

Hybrid PQC/TLS Deployment

The safest migration path uses hybrid mode — combining classical and post-quantum algorithms:

# Nginx configuration for hybrid TLS
ssl_protocols TLSv1.3;
ssl_ecdh_curve X25519Kyber768Draft00:X25519:P-256;
ssl_prefer_server_ciphers on;

This ensures security even if one algorithm is compromised.

Infrastructure Migration Checklist

1. Inventory all cryptographic usage — TLS certificates, SSH keys, API tokens, database encryption, secrets management
2. Classify data by sensitivity and lifespan — Healthcare records, financial data, and government secrets need PQC first
3. Update TLS libraries — OpenSSL 3.x and BoringSSL support PQC algorithms
4. Test performance impact — PQC key sizes are larger, affecting handshake times
5. Migrate certificates — Start with internal services, then external-facing
6. Update key management — KMS and HSM systems need PQC support
7. Audit CI/CD pipelines — Ensure build and deploy processes use PQC-safe crypto

Performance Considerations

PQC algorithms have different performance characteristics:

Larger key and signature sizes increase bandwidth and storage requirements. Plan for 2-5x larger TLS handshakes.

Kubernetes and PQC

For Kubernetes clusters, focus on:

• etcd encryption: Rotate encryption keys to PQC-safe algorithms
• Service mesh TLS: Update Istio/Linkerd CA certificates
• Secrets management: Ensure Vault or KMS supports PQC
• Container image signing: Update Sigstore/cosign to PQC signatures

Cloud Provider PQC Support (2026)

• AWS: KMS supports ML-KEM, S3 hybrid encryption available
• GCP: Cloud KMS PQC preview, Certificate Authority Service with hybrid certs
• Azure: Key Vault PQC preview, hybrid TLS on Application Gateway

FAQ

When will quantum computers break current encryption? Estimates range from 2030 to 2040+. The exact timeline is uncertain, which is why migration should start now.

Can I just switch to PQC overnight? No. PQC migration is a multi-year process. Start with inventory and hybrid deployments.

Does PQC affect application performance? Slightly. Larger keys increase TLS handshake time by 10-30ms. For most applications, this is negligible.

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