Hybrid migration is a staged transition in which legacy cryptographic methods operate alongside post-quantum methods. It lets organizations update systems gradually, rather than replacing every cryptographic component at once.
In post-quantum security, this overlap can help maintain compatibility while teams test new algorithms across applications, devices, and integrations. It also adds complexity: systems must correctly negotiate or verify both methods, and defenders need to track where each is used. A cryptographic inventory and clear transition plan help reduce configuration errors and ensure legacy methods are eventually retired where appropriate.