midCryptography
What is Perfect Forward Secrecy (PFS)?
Updated Apr 28, 2026
Short answer
A feature of specific key agreement protocols that ensures that session keys are not compromised even if private keys are compromised later.
Deep explanation
Mid-level cryptography moves into protocol design and implementation details. Understanding how primitives like Diffie-Hellman combine with AES to create a secure channel is key.
Real-world example
VPNs use Diffie-Hellman to establish a shared secret without ever sending the secret key over the wire.
Common mistakes
- Reusing an Initialization Vector (IV) with the same key in AES-GCM.
Follow-up questions
- What is the difference between AES-CBC and AES-GCM?
- Why is RSA slower than AES?