Post-Quantum Cryptography for Enterprise Infrastructure: The Migration Guide

Quantum computers capable of breaking RSA-2048 and ECC don't exist yet. But "harvest now, decrypt later" attacks do — adversaries collecting encrypted data today to decrypt when quantum computers arrive. For regulated enterprises handling sensitive data with multi-decade retention requirements, the migration to post-quantum cryptography must start now.

The Quantum Threat

• Shor's algorithm — Breaks RSA, DSA, ECDSA, ECDH, and Diffie-Hellman in polynomial time on a quantum computer
• Grover's algorithm — Halves the effective security of symmetric algorithms (AES-128 → 64-bit security). AES-256 remains safe
• Timeline — Estimates range from 2030-2040 for cryptographically relevant quantum computers. NIST considers the threat imminent enough to standardize PQC now
• Harvest now, decrypt later — Data encrypted today with RSA/ECC can be stored and decrypted when quantum computers exist

NIST Post-Quantum Standards (Finalized 2024)

• ML-KEM (FIPS 203) — Module-Lattice-Based Key Encapsulation Mechanism (formerly Kyber). Replaces RSA/ECDH for key exchange
• ML-DSA (FIPS 204) — Module-Lattice-Based Digital Signature Algorithm (formerly Dilithium). Replaces RSA/ECDSA for digital signatures
• SLH-DSA (FIPS 205) — Stateless Hash-Based Digital Signature Algorithm (formerly SPHINCS+). Hash-based alternative for signatures
• FN-DSA (draft) — FFT over NTRU-Lattice-Based Digital Signature Algorithm (formerly Falcon). Compact signatures

Migration Strategy for Enterprises

Phase 1: Cryptographic Inventory (Now)

You can't migrate what you can't find. Inventory every use of vulnerable cryptography: TLS certificates, code signing, VPN tunnels, database encryption keys, API authentication tokens, document signatures. Automated scanning tools: CryptoSense, IBM Quantum Safe Explorer, custom AST-based scanning.

Phase 2: Hybrid Deployment (2025-2027)

Use hybrid key exchange — classical + post-quantum algorithms combined. If either is secure, the connection is secure. Chrome and Firefox already support X25519+ML-KEM-768 hybrid key exchange. Deploy hybrid TLS on your infrastructure to protect against harvest-now attacks.

Phase 3: Full Migration (2027-2030)

Transition to PQC-only where possible. Update PKI infrastructure, HSMs, and key management systems. Replace RSA/ECC certificates with PQC certificates as ecosystem support matures.

Infrastructure Actions Today

• Enable hybrid PQC key exchange on TLS endpoints (OpenSSL 3.2+, BoringSSL)
• Test application compatibility with PQC — larger key sizes and signatures impact performance
• Ensure HSMs support PQC algorithms (or plan replacement)
• Update procurement requirements — new cryptographic products must support PQC