Require forward-secret ciphers on Caddy

Why it matters

The server accepts ciphers where one stolen private key can decrypt all recorded past traffic. Forward-secret ciphers (ECDHE) are supported by every current client.

Staged change. Do this in stages and check each one before the next, so a mistake does not break your site or your mail.

The fix

1. Caddy cannot enable RSA key exchange. Its Caddyfile rejects those suite names, and its defaults are all forward secret.
2. If the scan sees such suites, TLS is terminated by something in front of Caddy (a load balancer, a CDN or another server listening on 443). Fix the cipher setting there.

Read the documentation ↗(opens in a new tab)

Related

• Reported by the cipher suites check
• Disable the RC4 cipher
• Disable the 3DES cipher
• Offer modern AEAD ciphers
• Retire the old TLS versions that use CBC ciphers