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Security Fundamentals & Crypto · Intermediate

Automated Certificate Management Environment (ACME)

Protocol (RFC 8555) that automates domain validation, issuance, and renewal of certificates.

Definition

ACME clients prove control of a domain through HTTP-01, DNS-01, or TLS-ALPN-01 challenges and then obtain certificates. Created for Let's Encrypt, it is now supported by many public and private CAs. It is key to managing short certificate lifetimes.

Example

certbot --nginx -d www.example.com obtains and installs a certificate and sets up automatic renewal.

Exam tip

DNS-01 is required for wildcard certificates with Let's Encrypt.

Related terms