ACME
acronymsecuritycryptography
Stands for: Automatic Certificate Management Environment
A protocol that automates getting and renewing TLS certificates.
Automatic Certificate Management Environment (RFC 8555) is the protocol behind Let's Encrypt and similar CAs. It lets a client prove domain control and obtain certificates without human interaction, which is why free, auto-renewing TLS became universal.
ACME turned certificate issuance from a purchasing process into an API call, and that single change is why HTTPS went from a minority of the web to nearly all of it. Before it, getting a certificate meant a vendor, a payment, and manual verification, which is a fine annual ritual and a terrible thing to do every sixty days.
The protocol's core is proving you control a name. HTTP validation serves a token at a well-known path; DNS validation publishes a token as a TXT record. The DNS method is the one that scales to wildcards and to hosts with no public web server, which is why it dominates in infrastructure work and why automating DNS updates becomes the real integration effort.
Short lifetimes are the design intent, not a limitation. If renewal is automated, ninety days is no harder than a year and dramatically shortens the window a compromised key stays useful. The corollary is that automation is not optional: a manual ACME workflow gives you all the frequency and none of the benefit, and the outage comes at whatever hour the certificate expires.
Also known as: acme