Post-Quantum Cryptography (PQC) is a new generation of cryptography designed to resist attacks by quantum computers, while running on the computers and networks we use today. It does not require quantum hardware.

INFOGRAPHIC
Harvest now, decrypt later: why planning must start early
01
Today: capture the data
Attackers store data encrypted with RSA/ECC
02
Later: a capable quantum computer exists
Nobody knows the exact date
03
Decrypt retroactively
Data that should still be secret is exposed
INFOGRAPHIC
What is affected, and what still holds

AFFECTED

  • RSAEncryption and signatures
  • Diffie-Hellman and ECCKey exchange and signatures

STILL OK / REPLACEMENT

  • AES-256 and strong hashesSymmetric encryption remains usable
  • ML-KEMReplaces key exchange (FIPS 203)
  • ML-DSA and SLH-DSAReplace digital signatures (FIPS 204, 205)

The quantum risk to today's cryptography

  • RSA and ECC can be broken in theory: Shor's algorithm on a large enough quantum computer can solve the problems that RSA, Diffie-Hellman, and ECC rely on. This affects TLS, VPNs, digital certificates, and digital signatures
  • Harvest now, decrypt later: attackers can capture encrypted data today and decrypt it once a capable quantum computer exists. Data that must stay secret for decades is already at risk
  • Nobody knows the exact date: no quantum computer can break this cryptography today, but migrating an organization's cryptography takes years, so work should start before it is urgent
  • What is less affected: symmetric encryption such as AES-256 and strong hashes remain usable. The main problem is key exchange and digital signatures

NIST PQC standards already published

In 2024 NIST published its first PQC standards: ML-KEM (FIPS 203) for key exchange, and ML-DSA (FIPS 204) and SLH-DSA (FIPS 205) for digital signatures, with more in development. Several providers and browsers already support hybrid key exchange in TLS.

How to prepare your organization for PQC

  • Build a crypto inventory: find where RSA/ECC is used, such as TLS, VPNs, PKI, code signing, databases, and embedded devices
  • Prioritize by data secrecy lifetime: data that must stay confidential for many years (health, financial, national security) comes first
  • Design for crypto-agility: avoid hard-coding algorithms in code or hardware that can't be changed
  • Ask vendors for their plans: request PQC roadmaps for firewalls, VPNs, PKI, HSMs, and software, and make them a criterion in the next procurement round
  • Pilot hybrid modes: start with lower-risk systems such as outbound TLS or internal services to measure performance and compatibility impact
  • Follow regulator guidance: such as the RSA/ECC deprecation timelines published by NIST and national agencies

Start preparing for PQC today

Begin with a crypto inventory and identify the data that must stay secret long-term. Neither needs new tools, and every later step depends on them.

Automated certificate rotation is the foundation for changing algorithms later. See Certificate Lifecycle Management in the 47-Day Era.

Designing for crypto-agility and building a cryptographic inventory are covered in Crypto-Agility and CBOM: Getting Ready for Post-Quantum.

References and further reading