Post-quantum cryptography, or PQC, is a new generation of encryption and digital-signature algorithms designed to stay secure even against a powerful quantum computer. This guide explains what post-quantum cryptography is, why it is needed, and what the recent NIST standards mean, all in plain terms and without assuming a background in cryptography. Why quantum computers threaten today's encryption Much of today's security relies on mathematical problems, such as factoring very large numbers, that ordinary computers cannot solve in any reasonable time. A sufficiently powerful quantum computer could solve some of these problems dramatically faster, breaking the public-key cryptography used almost everywhere. That would undermine the encryption protecting web traffic, the digital signatures that prove authenticity, and vast amounts of stored data. In short, a core assumption behind modern digital trust would no longer hold. How post-quantum cryptography responds PQC algorithms are built on different mathematical problems that are believed to resist attacks from both classical and quantum computers. Importantly, they run on today's ordinary hardware, so no quantum computer is needed in order to use them. In 2024, NIST finalised its first PQC standards, including a key-encapsulation mechanism and a digital-signature scheme, giving organisations concrete, vetted algorithms to begin adopting rather than research prototypes. Why it matters now The risk is not confined to the future. Encrypted data captured today could be stored and then decrypted once quantum computers mature, a strategy widely described as harvest now, decrypt later. Any data that must stay confidential for years is therefore already exposed. For that reason, forward-looking organisations are beginning to inventory where they use cryptography and to plan a gradual, orderly migration to quantum-resistant algorithms. What organisations can do first The practical starting point is visibility: understanding where cryptography and digital certificates are used across the business. From there, organisations can prioritise the systems that protect long-lived or sensitive data and pilot the new standards in a controlled way, building the agility to change algorithms as guidance evolves. Get ready for the quantum era eMudhra helps organisations understand and prepare for post-quantum cryptography. Want a place to start? Talk to an eMudhra expert. Tags: Post Quantum Cryptography About the Author eMudhra Limited eMudhra Editorial represents the collective voice of eMudhra, providing expert insights on the latest trends in digital security, cryptographic identities, and digital transformation. Our team of industry specialists curates and delivers thought-provoking content aimed at helping businesses navigate the evolving landscape of cybersecurity and trust services with confidence.