A framework for building letsencrypt clients, forked from letiny

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A framework for building letsencrypt clients, forked from letiny.
Supports all of:
node with ursa (works fast) node with forge (works on windows) browser WebCrypto (not implemented, but... Let's Encrypt over WebRTC anyone?) any javascript implementation
NEW: Let's Encrypt v2 Support
Let's Encrypt v2 (aka ACME v2 or ACME draft 11) is available in acme-v2.js

These aren't the droids you're looking for

This is a library / framework for building letsencrypt clients. You probably want one of these pre-built clients instead:
letsencrypt (compatible with the official client) letiny (lightweight client cli) letsencrypt-express (automatic https for express)

Install & Usage:

npm install --save le-acme-core

To use the default dependencies:
'use strict';

var ACME = require('le-acme-core').ACME.create();

For testing and development, you can also inject the dependencies you want to use:
'use strict';

var ACME = require('le-acme-core').ACME.create({
, RSA: require('rsa-compat').RSA

ACME.getAcmeUrls(discoveryUrl, function (err, urls) {

You will follow these steps to obtain certificates:
  • discover ACME registration urls with getAcmeUrls
  • register a user account with registerNewAccount
  • implement a method to agree to the terms of service as agreeToTos
  • get certificates with getCertificate
  • implement a method to store the challenge token as setChallenge
  • implement a method to get the challenge token as getChallenge
  • implement a method to remove the challenge token as removeChallenge


You can see this working for yourself, but you'll need to be on an internet connected computer with a domain.
Get a temporary domain for testing
npm install -g ddns-cli
ddns --random --email user@example.com --agree

Note: use YOUR EMAIL and accept the terms of service (run ddns --help to see them).

Install le-acme-core and its dependencies. Note: it's okay if you're on windows and ursa fails to compile. It'll still work.
git clone https://git.coolaj86.com/coolaj86/le-acme-core.js.git ~/le-acme-core
pushd ~/le-acme-core

npm install

Run the demo:
node examples/letsencrypt.js user@example.com example.com



The Goodies
// Accounts
ACME.registerNewAccount(options, cb)        // returns "regr" registration data

    { newRegUrl: '<url>'                      //    no defaults, specify acmeUrls.newAuthz
    , email: '<email>'                        //    valid email (server checks MX records)
    , accountKeypair: {                       //    privateKeyPem or privateKeyJwt
        privateKeyPem: '<ASCII PEM>'
    , agreeToTerms: fn (tosUrl, cb) {}        //    must specify agree=tosUrl to continue (or falsey to end)

// Registration
ACME.getCertificate(options, cb)            // returns (err, pems={ privkey (key), cert, chain (ca) })

    { newAuthzUrl: '<url>'                    //    specify acmeUrls.newAuthz
    , newCertUrl: '<url>'                     //    specify acmeUrls.newCert

    , domainKeypair: {
        privateKeyPem: '<ASCII PEM>'
    , accountKeypair: {
        privateKeyPem: '<ASCII PEM>'
    , domains: ['example.com']

    , setChallenge: fn (hostname, key, val, cb)
    , removeChallenge: fn (hostname, key, cb)

// Discovery URLs
ACME.getAcmeUrls(acmeDiscoveryUrl, cb)      // returns (err, acmeUrls={newReg,newAuthz,newCert,revokeCert})

Helpers & Stuff
// Constants
ACME.productionServerUrl                // https://acme-v01.api.letsencrypt.org/directory
ACME.stagingServerUrl                   // https://acme-staging.api.letsencrypt.org/directory
ACME.acmeChallengePrefix                // /.well-known/acme-challenge/
ACME.knownEndpoints                     // new-authz, new-cert, new-reg, revoke-cert

// HTTP Client Helpers
ACME.Acme                               // Signs requests with JWK
    acme = new Acme(keypair)                // 'keypair' is an object with `privateKeyPem` and/or `privateKeyJwk`
    acme.post(url, body, cb)                // POST with signature
    acme.parseLinks(link)                   // (internal) parses 'link' header
    acme.getNonce(url, cb)                  // (internal) HEAD request to get 'replay-nonce' strings


Below you'll find a stripped-down example. You can see the full example in the example folder.

Register Account & Domain

This is how you register an ACME account and get an HTTPS certificate
'use strict';

var ACME = require('le-acme-core').ACME.create();
var RSA = require('rsa-compat').RSA;

var email = 'user@example.com';                   // CHANGE TO YOUR EMAIL
var domains = 'example.com';                      // CHANGE TO YOUR DOMAIN
var acmeDiscoveryUrl = ACME.stagingServerUrl;   // CHANGE to production, when ready

var accountKeypair = null;                        // { privateKeyPem: null, privateKeyJwk: null };
var domainKeypair = null;                         // same as above
var acmeUrls = null;

RSA.generateKeypair(2048, 65537, function (err, keypair) {
    accountKeypair = keypair;
    // ...
    ACME.getAcmeUrls(acmeDiscoveryUrl, function (err, urls) {
        // ...

function runDemo() {
        { newRegUrl: acmeUrls.newReg
        , email: email
        , accountKeypair: accountKeypair
        , agreeToTerms: function (tosUrl, done) {

              // agree to the exact version of these terms
              done(null, tosUrl);
      , function (err, regr) {

                { newAuthzUrl: acmeUrls.newAuthz
                , newCertUrl: acmeUrls.newCert

                , domainKeypair: domainKeypair
                , accountKeypair: accountKeypair
                , domains: domains

                , setChallenge: challengeStore.set
                , removeChallenge: challengeStore.remove
              , function (err, certs) {

                  // Note: you should save certs to disk (or db)
                  certStore.set(domains[0], certs, function () {

                      // ...



But wait, there's more! See example/letsencrypt.js

Run a Server on 80, 443, and 5001 (https/tls)

That will fail unless you have a webserver running on 80 and 443 (or 5001) to respond to /.well-known/acme-challenge/xxxxxxxx with the proper token
var https = require('https');
var http = require('http');

var LeCore = deps.LeCore;
var tlsOptions = deps.tlsOptions;
var challengeStore = deps.challengeStore;
var certStore = deps.certStore;

// Challenge Handler
function acmeResponder(req, res) {
  if (0 !== req.url.indexOf(LeCore.acmeChallengePrefix)) {
    res.end('Hello World!');

  var key = req.url.slice(LeCore.acmeChallengePrefix.length);

  challengeStore.get(req.hostname, key, function (err, val) {
    res.end(val || 'Error');

// Server
https.createServer(tlsOptions, acmeResponder).listen(5001, function () {
  console.log('Listening https on', this.address());
http.createServer(acmeResponder).listen(80, function () {
  console.log('Listening http on', this.address());

But wait, there's more! See example/serve.js

Put some storage in place

Finally, you need an implementation of challengeStore:
var challengeCache = {};
var challengeStore = {
  set: function (hostname, key, value, cb) {
    challengeCache[key] = value;
, get: function (hostname, key, cb) {
    cb(null, challengeCache[key]);
, remove: function (hostname, key, cb) {
    delete challengeCache[key];

var certCache = {};
var certStore = {
  set: function (hostname, certs, cb) {
    certCache[hostname] = certs;
, get: function (hostname, cb) {
    cb(null, certCache[hostname]);
, remove: function (hostname, cb) {
    delete certCache[hostname];

But wait, there's more! See


ISRG Anatol Sommer (https://github.com/anatolsommer) AJ ONeal (https://coolaj86.com)


MPL 2.0
All of the code is available under the MPL-2.0.
Some of the files are original work not modified from letiny and are made available under MIT and Apache-2.0 as well (check file headers).