!!! Overview
[{$pagename}] ([ACME]) is an evolving [Internet Draft] 

Certificates in the Web's [X.509] [PKI] ([PKIX]) are used for a number of purposes, the most significant of which is the [authentication] of [DNS Domain].  Thus, [Certificate Authorities|Certificate Authority] in the Web [PKI] are trusted to verify that an applicant for a [certificate] legitimately represents the [DNS Domain] name(s) in the [certificate].  Today, this verification is done through a collection of [Ad Hoc] mechanisms.  [{$pagename}] describes a [protocol] that a [Certificate Authority] (CA) and an applicant can use to automate the process of verification and [Certificate Request Process].  The [protocol] also provides facilities for other [certificate] management functions, such as [certificate Revocation].

* [Certbot] is an [implementation] of an [{$pagename}] [client].
* [Let's Encrypt|Lets encrypt] uses [Boulder] which is an [implementation] of an [ACME]-based [Certificate Authority]

!! Introduction
[Certificates] in the Web [PKI] are most commonly used to [authenticate] [DNS Domain] names.  

Thus, [certificate authorities|Certificate Authority] in the Web [PKI] are trusted to verify that an applicant for a [certificate] legitimately represents the [DNS Domain] name(s) in the [certificate].

Existing Web [PKI] [certificate authorities|Certificate Authority] tend to run on a set of [Ad Hoc] [protocols] for [certificate] issuance and [identity Proofing].  A typical user experience is something like:
* Generate a [PKCS10] [RFC 2314] [Certificate Signing Request] ([CSR]).
* Cut-and-paste the [CSR] into a [Certificate Authority] web page.
* Prove ownership of the domain by one of the following methods:
** Put a CA-provided challenge at a specific place on the web server.
** Put a CA-provided challenge at a DNS location corresponding to the target domain.
** eceive CA challenge at a (hopefully) administrator-controlled e-mail address corresponding to the domain and then respond to it on the CA's web page.
* Download the issued certificate and install it on their Web Server.

With the exception of the [Certificate Signing Request] itself and the [certificates] that are issued, these are all completely [Ad Hoc] procedures and are accomplished by getting the human user to follow interactive natural-language instructions from the [CA] rather than by [machine-to-machine] [protocols].  In many cases, the instructions are difficult to follow and cause significant confusion.  Informal usability tests by the authors indicate that webmasters often need 1-3 hours to obtain and install a [certificate] for a [DNS Domain].  Even in the best case, the lack of published, standardized mechanisms presents an obstacle to the wide deployment of [HTTPS] and other [PKIX]-dependent systems because it inhibits mechanization of tasks related to certificate issuance, deployment, and revocation.

[{$pagename}] describes an extensible framework for automating the issuance and [DNS Domain] validation procedure, thereby allowing servers and infrastructural software to obtain [certificates] without user interaction.  Use of this [protocol] should radically simplify the deployment of [HTTPS] and the practicality of PKIX [authentication] for other protocols based on [TLS].

!! [{$pagename}] on [Github|https://github.com/ietf-wg-acme/acme|target='_blank']
Has the working area for the Working Group internet-draft, "[{$pagename}] ([ACME])" with supporting code.

!! More Information
There might be more information for this subject on one of the following:
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* [#1] - [Automated Certificate Management Environment (acme)|https://datatracker.ietf.org/wg/acme/documents/|target='_blank'] - based on information obtained 2018-07-22-