Glossary · Security

ECDHE

Elliptic Curve Diffie-Hellman Ephemeral

In plain language

A method that lets two computers agree on a fresh secret key for each session, even while someone is watching.

The metaphor

Like two people each mixing a private colour into a shared paint tin and swapping the mixes: both end up with the same final colour, and a watcher cannot work it out.

Going deeper

How it works

Each connection creates a temporary key that is thrown away afterwards.
Because the key is not reused, stealing a server's long-term key later cannot unlock old recorded traffic.
This property is called perfect forward secrecy.
It is common in modern HTTPS and VPN connections.

In practice

Your browser uses it each time you open a secure website.
A security scan lists it as a preferred setting for a web server.
A VPN uses it to set up a new key every time it connects.

A question owners ask

Is this something I configure?

Almost never. If a scan says your website lacks it, your web host or developer can turn it on.

Related terms

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