CompTIA Exam Prep - ITF+, A+, Network+, Security+, CySA+

 Perfect Forward Secrecy  Perfect Forward Secrecy (PFS) is a property of secure communication protocols that ensures: If long‑term keys are ever compromised in the future, past encrypted communications remain secure. In other words, even if an attacker steals your server’s private key years later, they still cannot decrypt old traffic they recorded. This is a huge deal for long‑term privacy. Why PFS Exists Traditional encryption (without PFS) works like this: A server has a long‑term private key Clients use that key to negotiate encryption If someone records the traffic and later steals the private key, they can decrypt everything This is a catastrophic failure mode. PFS fixes that by ensuring each session uses a unique, temporary key that is destroyed after use. How PFS Works (Step-by-Step) 1. Ephemeral key exchange Protocols with PFS use ephemeral Diffie–Hellman: DHE (Diffie–Hellman Ephemeral) ECDHE (Elliptic Curve Diffie–Hellman Ephemeral) “Ephemeral” means the key exists o...

 What PGP Actually Is Pretty Good Privacy (PGP) is a cryptographic system used for: Encrypting data (emails, files, backups) Digitally signing data (proving authenticity and integrity) Managing keys (public/private keypairs) PGP uses a hybrid cryptosystem: Asymmetric encryption (public/private keys) to exchange a session key Symmetric encryption (fast algorithms like AES) to encrypt the actual data This gives you the best of both worlds: strong identity verification and efficient encryption. How PGP Works (Step-by-Step) 1. Keypair creation You generate: A public key (shared with the world) A private key (kept secret) 2. Encrypting a message The sender encrypts the message using your public key Only your private key can decrypt it 3. Signing a message The sender signs the message with their private key Anyone can verify the signature using the sender’s public key This gives: Confidentiality (only the intended recipient can read it) Integrity (message wasn’t altered) Authentication (...