Perfect forward secrecy (PFS) explained

Perfect forward secrecy (PFS) is a security feature used in cryptographic systems (e.g. VPNconnections) to protect data from being compromised, even if the encryption keys are taken over or guessed by an unauthorized third party.

PFS achieved by regularly changing the encryption keys used in the encryption. In this way, only a limited amount of data is exposed if an unauthorized third party gets hold of the encryption keys.

Perfect forward secrecy increases the safety of VPN-connections

One of the most common uses of perfect forward secrecy er i VPN-connections (Virtual Private Network). VPNconnections enable users to establish a secure, encrypted connection to another network over the Internet.

This can be useful to ensure that data cannot be intercepted while being transmitted, or to allow users to access networks that would otherwise be inaccessible to them.

Når and VPNconnection is established, two encryption keys are generated: a public key and a private key. Public keys are used to encrypt data sent over the Internet, while private keys are used to decrypt data when it is received. These keys are exchanged between VPN- the client and VPNserver, and they are used to establish a secure, encrypted connection between the two.

PFS works by regularly changing the keys used to encrypt your data. Instead of using the same key to encrypt all data passed through VPNconnection, a new, temporary key is created for each individual data transfer. When data is sent, it is encrypted with this temporary key, and the recipient can then decrypt it with the same key.

In this way, an unauthorized third party who has obtained the encryption keys can only gain access to the individual data transfer. The other data is still safe as it is encrypted with other keys. keys.

VPN-connections often use ephemeral keys for PFS

There are several different techniques that can be used to achieve this perfect forward secrecy i VPN-connections. One of the most common techniques is to apply ephemeral keys, which are temporary keys generated for each session.

Når and VPNconnection is established, a new ephemeral key is generated, which is used to encrypt all data sent over the connection. When the session ends, the key ceases to be valid and a new key is generated on the next connection.

Read more about PFS i ExpressVPNs blog post.