Also known as: PQC · quantum-resistant cryptography
Post-quantum cryptography refers to cryptographic algorithms designed to remain secure against attacks by quantum computers, which would break the public-key algorithms such as RSA and elliptic-curve cryptography that currently secure most internet traffic.
The urgency is driven by harvest-now-decrypt-later: an adversary recording encrypted traffic today could decrypt it once a sufficiently capable quantum computer exists. For data with a long confidentiality lifetime, that threat is present-tense regardless of when the hardware arrives.
NIST has standardised an initial set of post-quantum algorithms, and major browsers and messaging platforms have begun deploying hybrid schemes that combine a classical and a post-quantum algorithm — so the result is no weaker than today's cryptography even if the new algorithm proves flawed.
Forward Secrecy
Forward secrecy is a property of encryption protocols ensuring that if a long-term private key is later compromised, past recorded sessions still cannot be decrypted, because each session used ephemeral keys that were discarded afterwards.
End-to-End Encryption
End-to-end encryption (E2EE) is a system in which messages are encrypted on the sender's device and decrypted only on the recipient's, so that no intermediary — including the service provider — can read the content in transit or at rest on its servers.
TLS
TLS (Transport Layer Security) is the cryptographic protocol that encrypts data in transit between clients and servers, providing confidentiality, integrity, and server authentication — most visibly as the S in HTTPS.
Encryption at Rest
Encryption at rest is the encryption of stored data — on disks, in databases, or in backups — so that physical access to the storage medium does not yield readable data.