Perfect Forward Secrecy (PFS)
Definition
Property of a key exchange where compromise of a long-term private key does not let the attacker decrypt past sessions. Achieved by ephemeral Diffie-Hellman (DHE or ECDHE).
Related terms
- Brute Force
- Exhaustive search over the key space. The benchmark every other attack must beat. AES-128 brute force is computationally infeasible on classical hardware;...
- Cryptanalysis
- The study of breaking cryptographic systems. Complement to cryptography. Goals include recovering the key, recovering the plaintext, or distinguishing a cipher's output...
- Diffie-Hellman
- Key exchange protocol by Diffie, Hellman and Merkle (1976) that lets two parties agree on a shared secret over a public channel....
- Padding Oracle
- An attack that uses an error-message distinction (or a timing distinction) between 'padding invalid' and 'authentication invalid' to recover plaintext from CBC-mode...
- Post-Quantum Cryptography (PQC)
- Algorithms designed to resist attacks by sufficiently capable quantum computers. NIST standardised CRYSTALS-Kyber as ML-KEM and CRYSTALS-Dilithium as ML-DSA in 2024.
- Side-Channel Attack
- Attack that exploits information leaked by a correct implementation: timing, power consumption, electromagnetic emanation, cache state, acoustic noise. Independent of the algebra...
Explained in
- Cryptanalysis, Cryptographic Attacks and Diffie-Hellman Key ExchangeProperty of a key exchange where compromise of a long-term private key does not let the attacker decrypt past sessions. Achieved by ephemeral Diffie-Hellman (D...