Question

A financial services company must begin migrating its externally-facing TLS infrastructure to resist future quantum attacks while maintaining compatibility with a large base of legacy clients that only support classical algorithms. The security architect wants an approach that provides protection against 'harvest-now, decrypt-later' attacks without breaking interoperability during the transition. Which approach best meets these requirements?

Accepted Answer

Deploy hybrid key exchange that combines a classical algorithm (e.g., ECDHE) with a NIST-selected post-quantum KEM (e.g., ML-KEM) in the TLS handshake

Answer

Immediately replace all RSA and ECC certificates with pure ML-DSA (Dilithium) certificates and disable classical cipher suites

Answer

Increase RSA key sizes to 15360 bits across all certificates to achieve quantum resistance

Answer

Enable perfect forward secrecy with ECDHE and rotate session keys more frequently to defeat quantum decryption