Hybrid TLS
Major browsers and content delivery networks now default new TLS 1.3 handshakes to a hybrid of X25519 and ML-KEM-768, so a break of either algorithm alone isn't sufficient to compromise the session.
Part Two · Post-quantum cryptography
What is post-quantum cryptography, and why now?
Post-quantum cryptography (PQC) refers to cryptographic algorithms designed to run on today's classical computers while resisting attacks from both classical and quantum computers. Unlike quantum key distribution, PQC requires no special hardware — it's a software and standards migration, and it's already underway.
Why the migration is starting now, not later
The driving threat model is known as “harvest now, decrypt later.” An adversary intercepts and stores encrypted traffic today, with no ability to read it — but with the intention of decrypting it once a cryptographically relevant quantum computer exists. For data with a long confidentiality lifetime — medical records, state secrets, infrastructure designs, intellectual property — that data is already exposed under this model, even though no such machine has been built yet. Researchers currently project the arrival window for cryptographically relevant quantum computers at roughly 2033–2037.
Where PQC has already shipped
Post-quantum cryptography has moved from research into production faster than most enterprise cryptography transitions typically do, largely through hybrid deployments that combine a classical algorithm with a post-quantum one during the transition period.
Secure messaging
Apple's iMessage PQ3 protocol incorporates post-quantum key establishment specifically to defend against harvest-now-decrypt-later collection of message traffic.
Crypto-agility
Enterprises are increasingly building a dedicated “crypto-agility” control plane — inventory, policy, enforcement and telemetry layers — so algorithms can be swapped quickly if a standard is later weakened, rather than hard-coded into individual applications.