Forward secrecy
A property of a key exchange in which a later compromise of long-term keys does not expose past session keys, because each session uses ephemeral keys that are then discarded. TLS 1.3 provides it through (EC)DHE key exchange, though resumption with a pre-shared key alone does not.
- Also called
- perfect forward secrecy
Covered in
Choose cryptographic algorithms and parameters by job
A sourced quick reference for October 2026: which algorithm and parameters to use for encryption, hashing, passwords, MACs, signatures, key agreement, key derivation, randomness and TLS, the matching APIs in Node.js, Python, Java, Go and .NET, and where post-quantum migration stands.
Operate TLS and certificates: configuration, renewal and verification
Configure a modern TLS profile with hybrid post-quantum key exchange, automate renewal for certificate lifetimes that fall to 47 days, and verify every termination point with a fresh handshake.
Practice: Insecure randomness lab: Generate unguessable API keys