FORWARD SECRECY in TLS means

1. FORWARD SECRECY (also: 'Perfect Forward Secrecy'): a property where compromising the LONG-TERM key does NOT reveal past session data. 2. HOW: TLS handshakes that use EPHEMERAL Diffie-Hellman (ECDHE) generate a FRESH key per session. The session key isn't stored anywhere after the session ends. 3. CONTRAST with older RSA key exchange: the session key was encrypted with the server's long-term public key. If the private key leaks years later, all past sessions can be decrypted. 4. TLS 1.3 REQUIRES forward secrecy — all key exchanges use ECDHE. 5. Defends against: state-level adversaries recording today's traffic to decrypt years later. _Source: Boneh & Shoup, §21.4 (Forward secrecy in TLS) + RFC 8446._