• Cybersecurity Glossary
What is Post-Quantum Cryptography (PQC)?
Post-Quantum Cryptography (PQC) is the set of cryptographic algorithms designed to remain secure against attacks from both classical and quantum computers. Classical public-key systems RSA, Diffie-Hellman, and ECC rely on mathematical problems that quantum computers can solve efficiently using Shor’s algorithm. PQC algorithms replace those foundations with problems that remain hard for quantum machines: lattice problems, hash functions, and error-correcting codes. NIST finalized the first three PQC standards in August 2024 (FIPS 203, 204, 205), and migration has become a regulatory requirement. For enterprise networks protected by IPsec and SD-WAN tunnels, the transition to quantum safe cryptography is no longer optional.
Post-Quantum Cryptography definition
Post-Quantum Cryptography (PQC) is a family of cryptographic algorithms designed to resist attacks from quantum computers while running on classical hardware. The term distinguishes these algorithms from quantum cryptography which requires quantum hardware such as QKD devices because PQC can be deployed on existing network infrastructure without physical modifications.
Modern public-key cryptography rests on the computational hardness of two problems: integer factorization (RSA) and discrete logarithms (Diffie-Hellman, ECC). Both are solved efficiently by Shor’s algorithm on a quantum computer with enough stable qubits. PQC replaces those foundations with problems in different mathematical domains lattice geometry, hash functions, and linear error-correcting codes for which no efficient quantum algorithm is known.
NIST launched a formal standardization process in 2016 and published the first finalized standards in August 2024: FIPS 203 (ML-KEM, for key encapsulation), FIPS 204 (ML-DSA, for digital signatures), and FIPS 205 (SLH-DSA, for hash-based signatures). The U.S. government has mandated federal agencies to begin migration, with RSA and ECDSA scheduled for deprecation by 2030 and full disallowance by 2035.
NIST standards: ML-KEM, ML-DSA, SLH-DSA
NIST’s 2024 standards define the first quantum safe algorithms for production deployment. Each addresses a different cryptographic function, and together they cover the two categories that enterprise networks rely on most: key exchange and digital signatures.
PQC vs Classical cryptography
Classical cryptography and post-quantum cryptography are not competing for the same function PQC replaces the quantum-vulnerable components while symmetric encryption (AES-256) remains safe with no changes. The table below covers the attributes that matter most for enterprise network migration planning.
| Dimension | Classical cryptography | Post-Quantum Cryptography |
|---|---|---|
| Mathematical basis | Integer factorization (RSA) / discrete logarithm (ECC, DH) | Lattice problems (MLWE), hash functions, linear codes no known efficient quantum algorithm |
| Quantum vulnerability | Broken by Shor’s algorithm on a cryptographically relevant quantum computer | Designed to resist both classical and quantum attacks |
| Key / ciphertext size | Compact: 256-bit ECC key, 2048-bit RSA key | Larger: ML-KEM-768 public key ≈ 1.2 KB; ML-DSA signature ≈ 2.4 KB |
| Performance | Highly optimized after decades of deployment | Comparable on modern CPUs; some hardware acceleration recommended at scale |
| Standardization | Mature: PKCS, RFC, decades of production use | NIST FIPS 203/204/205 finalized August 2024; ecosystem maturing |
| Migration effort | No migration needed for symmetric (AES-256 stays safe) | Key exchange and signature algorithms must be replaced or augmented via hybrid |
| TLS / IPsec support | Fully integrated in all current implementations | Hybrid support in OpenSSL 3.x, BoringSSL, wolfSSL, IKEv2 via RFC 9370 |
| Regulatory status | RSA/ECDSA deprecated by U.S. federal mandate from 2030 | ML-KEM, ML-DSA, SLH-DSA: recommended for immediate deployment |
Why the urgency? The harvest-now-decrypt-later threat means the migration clock started before quantum computers exist at scale. Data captured today with a long confidentiality horizon VPN traffic, healthcare records, financial transactions can be decrypted later. Organizations that start migration now have time to phase in PQC without disrupting production networks.
The harvest-now-decrypt-later threat
The quantum threat is not purely future: one of its most dangerous dimensions is already active. Understanding the attack landscape helps security teams prioritize which systems to protect first.
The action threshold: NIST’s NCCoE recommends that organizations begin migration if their data has a confidentiality requirement exceeding five years. For SD-WAN operators, this means deploying PS-PPK now as an immediate HNDL mitigation, followed by ML-KEM integration as part of a structured quantum transition roadmap.
Migration challenges
Transitioning enterprise cryptography to PQC is a multi-year effort. Each challenge below has a defined mitigation none of them is a reason to delay, but all of them require planning.
Deployment framework
A phased approach allows organizations to address the most urgent risks immediately while building toward full PQC migration over time. The steps below follow current NIST NCCoE and NSA CNSA 2.0 guidance, adapted for enterprise network operators.
Teldat Quantum SD-WAN solutions
Teldat has built post-quantum protection directly into its SD-WAN infrastructure, allowing organizations to address quantum threats at the network layer without waiting for a full cryptographic overhaul of every application and endpoint. The Quantum SD-WAN roadmap is built on four technological pillars, each addressing a different phase of the quantum threat timeline:
The Teldat quantum advantage: As a network hardware manufacturer and cybersecurity provider, Teldat delivers quantum safe SD-WAN capabilities from a unified ecosystem. PS-PPK for immediate protection, ML-KEM for standards-based quantum resistance, QKD for future-proof key generation, embedded NGFW for defense in depth, and CNM for centralized management are all integrated into a single platform. Organizations can begin their quantum transition today without replacing their network infrastructure or managing multiple vendor solutions.
Frequently asked questions about Post-Quantum Cryptography – (FAQ’s)
❯ What is Post-Quantum Cryptography in simple terms?
Post-Quantum Cryptography (PQC) is a set of cryptographic algorithms designed to be secure against attacks from both classical and quantum computers. Unlike current public-key systems that rely on factoring large numbers or discrete logarithm problems both solvable by a quantum computer using Shor’s algorithm PQC algorithms are based on mathematical problems for which no efficient quantum algorithm is known, such as finding short vectors in high-dimensional lattices.
❯ Why is current encryption vulnerable to quantum computers?
Classical public-key cryptography RSA, Diffie-Hellman, and ECC relies on the computational hardness of integer factorization and discrete logarithm problems. Shor’s algorithm, running on a sufficiently powerful quantum computer, solves both problems in polynomial time, effectively breaking the key exchange and signature mechanisms that protect virtually all encrypted communications today. Symmetric ciphers like AES-256 are much less affected and remain safe with no algorithm change.
❯ What is ML-KEM and why does it matter?
ML-KEM (Module Lattice Key Encapsulation Mechanism), standardized as NIST FIPS 203, is the primary post-quantum algorithm for key exchange. It replaces ECDH in TLS and IKEv2/IPsec handshakes, providing a quantum-resistant key agreement based on the hardness of the Module Learning With Errors (MLWE) lattice problem. It is the algorithm at the core of Teldat Quantum SD-WAN post-quantum key exchange.
❯ What is the harvest-now-decrypt-later threat?
Harvest-now-decrypt-later (HNDL) is an active attack strategy where adversaries capture and store encrypted network traffic today, then decrypt it once a quantum computer powerful enough to break the key exchange becomes available. It is particularly dangerous for data with long confidentiality requirements SD-WAN tunnel traffic, classified communications, healthcare records, financial contracts. The attack is occurring now; the decryption happens in the future.
❯ How does Teldat protect against quantum threats?
Teldat Quantum SD-WAN provides a layered quantum transition roadmap: PS-PPK (Pre-Shared Post-Quantum Keys, RFC 8784) for immediate harvest-now-decrypt-later mitigation on existing tunnels; ML-KEM (FIPS 203) integration for NIST-standardized post-quantum key exchange in IKEv2/IPsec; and QKD compatibility for future quantum safe key generation. All capabilities are managed centrally through Teldat CNM, with be.Safe Pro SSE extending protection to cloud delivered security services.
❯ When should organizations start migrating to PQC?
Now. NIST, NSA (CNSA 2.0), and ENISA all recommend beginning migration immediately, given the active harvest-now-decrypt-later threat and the long timelines involved in enterprise cryptographic migration. The recommended first step is a cryptographic inventory to identify quantum-vulnerable algorithms in use, followed by PS-PPK deployment as an immediate near-term mitigation, and then phased integration of ML-KEM for key exchange and ML-DSA for digital signatures.
Prepare your network for the Quantum Era with Teldat
From PS-PPK for immediate harvest-now-decrypt-later protection to ML-KEM for NIST standardized post-quantum key exchange, Teldat Quantum SD-WAN delivers quantum safe network security from a single integrated platform.
