// #proton-mail

Proton Mail Adds Post-Quantum Encryption for New Emails to Counter Harvest-Now-Decrypt-Later Attacks

Proton Mail has added optional post-quantum encryption for new emails sent between Proton Mail accounts, protecting against harvest-now-decrypt-later (HNDL) attacks in which adversaries collect encrypted communications today with the intention of decrypting them when sufficiently powerful quantum computers become available. The feature uses the CRYSTALS-Kyber (ML-KEM) algorithm standardised by NIST in 2024. Existing encrypted emails are not retroactively re-encrypted.