Proton Mail rolls out post-quantum encryption for all users as industry braces for ‘harvest now, decrypt later’ threat

Proton Mail has rolled out post-quantum encryption (PQC) to all users, including free accounts, as a defense against 'harvest now, decrypt later' attacks where adversaries collect encrypted data today to decrypt once quantum computers mature. The feature is opt-in via encryption key settings and applies to newly sent emails, layering on top of existing RSA and ECC standards rather than replacing them. Proton is also introducing OpenPGP v6 compatibility and collaborating with projects like Thunderbird to enable cross-provider quantum-safe email. NIST finalized its first PQC standards in 2024, and government mandates are accelerating, making Proton's consumer-facing rollout a notable milestone in the broader industry transition.