A property of secure communication protocols that protects past sessions even if long-term private keys are compromised. In cryptographic systems without PFS, if a private key is stolen, attackers could decrypt previously captured traffic. With PFS, however, each session generates unique, ephemeral keys through mechanisms like Diffie-Hellman or Elliptic Curve Diffie-Hellman key exchange.
This design ensures that even if an attacker later obtains a private key, they cannot retroactively decrypt past communications. PFS is widely used in protocols such as TLS, SSH, and VPNs, and it has become a best practice for securing sensitive internet traffic.
For businesses, enabling PFS means better protection of customer data and reduced exposure in the event of a breach. For consumers, it ensures that encrypted web traffic, messaging, or online banking remains private even if attackers attempt to exploit stolen credentials or certificates years later.
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