Post-Quantum Cryptography Readiness

Posted: March 6, 2026 to Quantum Computing.

Post-quantum cryptography (PQC) readiness is your organization's preparedness to replace RSA, ECC, and Diffie-Hellman encryption with quantum-resistant algorithms before quantum computers can break them. NIST finalized three PQC standards in August 2024 (ML-KEM, ML-DSA, SLH-DSA), and Google announced a 2029 migration deadline on March 25, 2026. With harvest-now-decrypt-later attacks already underway and cryptographic migration historically taking 5 to 10 years, the window to act is now, not when the first cryptographically relevant quantum computer (CRQC) arrives.

Post-Quantum Cryptography Readiness: Why Your Business Must Start Preparing for Quantum Computing Threats Now

Quantum computers capable of breaking current encryption standards are no longer a distant theoretical threat. NIST finalized its first three post-quantum cryptographic standards in 2024, and the migration timeline is measured in years, not decades. Organizations that wait until quantum computers can crack RSA and ECC encryption will find themselves scrambling to replace cryptographic infrastructure across every system, application, and communication channel simultaneously.

The threat is not just future-facing. "Harvest now, decrypt later" attacks are happening today. Adversaries, particularly nation-state actors, are intercepting and storing encrypted communications and data with the intention of decrypting them once quantum computing makes current encryption obsolete. If your data has long-term sensitivity, measured in years or decades, it is already at risk from quantum threats.

Understanding the Quantum Threat to Encryption

What Quantum Computing Changes

Current encryption relies on mathematical problems that classical computers cannot solve in reasonable time. RSA encryption depends on the difficulty of factoring large numbers. Elliptic curve cryptography depends on the discrete logarithm problem. These problems are computationally infeasible for classical computers but can be solved efficiently by a sufficiently powerful quantum computer running Shor's algorithm.

This means that RSA, ECC, Diffie-Hellman key exchange, and DSA digital signatures, the cryptographic foundations of virtually all secure communications and data protection, will become breakable. TLS/SSL connections, VPN tunnels, encrypted email, digital signatures, code signing, blockchain, and encrypted storage all rely on these algorithms.

What Remains Secure

Symmetric encryption algorithms like AES are less affected by quantum computing. Grover's algorithm provides a quadratic speedup for brute-force attacks on symmetric keys, which means AES-256 provides roughly AES-128 equivalent security against quantum attacks. This is still considered secure for most applications. The primary threat is to asymmetric (public key) cryptography.

Hash functions

SHA-256 and SHA-3 are also quantum-resistant with larger output sizes. The cryptographic infrastructure that needs replacement is primarily the public key algorithms used for key exchange, digital signatures, and authentication.

NIST Post-Quantum Cryptographic Standards

NIST finalized three post-quantum cryptographic algorithms that will replace current standards:

ML-KEM (formerly CRYSTALS-Kyber): A key encapsulation mechanism for secure key exchange. This replaces RSA and Diffie-Hellman for establishing encrypted connections. ML-KEM is recommended for TLS, VPN, and any application requiring secure key agreement.

ML-DSA (formerly CRYSTALS-Dilithium): A digital signature algorithm for authentication and integrity verification. This replaces RSA and ECDSA signatures used in code signing, document signing, certificate authorities, and authentication protocols.

SLH-DSA (formerly SPHINCS+): A hash-based digital signature algorithm providing an alternative signature scheme based on different mathematical assumptions. This serves as a backup in case lattice-based cryptography faces unexpected attacks.

A fourth algorithm, HQC, is in the final stages of standardization and will provide an alternative key encapsulation mechanism based on code-based cryptography.

Why Migration Must Start Now

Cryptographic Migration Takes Years

The last major cryptographic migration, from SHA-1 to SHA-2, took over a decade despite being a relatively simple hash algorithm replacement. Post-quantum migration is exponentially more complex because it affects key exchange, digital signatures, and authentication across every connected system. Large organizations have thousands of systems, applications, and integrations that rely on public key cryptography.

Harvest Now, Decrypt Later

Data encrypted today using RSA or ECC can be stored by adversaries and decrypted later when quantum computers become available. This means that data with long-term confidentiality requirements, including classified information, trade secrets, medical records, attorney-client communications, and intellectual property, is effectively at risk now. Organizations handling this type of data must begin transitioning to post-quantum encryption immediately.

Regulatory Requirements Are Emerging

Federal agencies are mandating post-quantum readiness timelines. NSA has directed National Security Systems to begin migration planning. CMMC and NIST frameworks will incorporate post-quantum requirements as standards mature. FIPS 140-3 will include post-quantum algorithms. Organizations that begin preparation now will be ahead of regulatory mandates rather than scrambling to meet deadlines.

Post-Quantum Readiness Assessment

Step 1: Cryptographic Inventory

Identify every use of public key cryptography in your environment. This includes TLS certificates, VPN configurations, SSH keys, code signing certificates, email encryption, disk encryption key management, database encryption, API authentication, and any custom applications that implement cryptographic functions. Most organizations are surprised by the breadth of their cryptographic footprint.

Step 2: Prioritize by Risk

Classify cryptographic usage by data sensitivity and longevity. Systems protecting data that must remain confidential for ten or more years are highest priority for migration. Systems with short-lived data sensitivity have more time but should still be included in migration planning.

Step 3: Evaluate Vendor Readiness

Contact your major software and infrastructure vendors to understand their post-quantum migration plans. Operating system vendors, cloud providers, VPN vendors, PKI providers, and application developers all have roles in the migration. Vendor readiness will determine your migration timeline for many systems.

Step 4: Test Hybrid Approaches

Hybrid cryptographic implementations that combine classical and post-quantum algorithms provide a transition path. TLS connections can negotiate hybrid key exchange that is secure against both classical and quantum attacks. Testing hybrid approaches in non-production environments builds organizational experience before production migration.

Step 5: Develop Migration Roadmap

Create a phased migration plan that addresses highest-risk systems first, accounts for vendor readiness timelines, includes testing and validation procedures, and maintains backward compatibility during the transition period. Budget for the migration over multiple fiscal years.

Post-Quantum Cryptography for Specific Industries

Defense contractors: Organizations handling CUI and classified information face the most urgent timelines. NSA and DoD directives will require post-quantum migration on specific schedules. Begin cryptographic inventory and planning immediately.

Healthcare: HIPAA requires encryption of protected health information. As post-quantum standards are incorporated into HIPAA guidance, organizations must be prepared to upgrade encryption across all PHI-handling systems.

Financial services: Banking and financial data has long-term confidentiality requirements that make it a prime target for harvest-now-decrypt-later attacks. Financial regulators will incorporate post-quantum requirements into existing cybersecurity frameworks.

Legal and professional services: Attorney-client privilege and confidential business information require long-term protection. Law firms and consulting organizations handling sensitive client data should prioritize post-quantum readiness.