Post-quantum encryption refers to cryptographic methods designed to remain secure even if attackers gain access to practical quantum computers. It is meant to replace or supplement today’s widely used public-key systems, which could become vulnerable to quantum attacks against certain mathematical problems.
It matters because encrypted data can stay valuable for years. In a “harvest now, decrypt later” attack, adversaries steal encrypted traffic or stored files today and wait for future advances to crack them. Defenders use post-quantum encryption to protect long-lived secrets such as records, identity systems, certificates, and secure communications. Adopting it usually requires a cryptographic inventory, careful migration planning, and testing to avoid breaking applications that depend on older standards.