diff --git a/README.md b/README.md
index 3cffabd..f5b6ae2 100644
--- a/README.md
+++ b/README.md
@@ -19,13 +19,18 @@ You will follow these steps to obtain certificates:
 * 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`
 
 ```javascript
 'use strict';
 
 var LeCore = require('letiny-core');
+
 var accountPrivateKeyPem = '...';                     // leCrypto.generateRsaKeypair(bitLen, exp, cb)
 var domainPrivateKeyPem = '...';                      // (same)
+var challengeStore = { /*get, set, remove*/ };        // see below for example
 
 LeCore.getAcmeUrls(
   LeCore.stagingServerUrl                             // or choose LeCore.productionServerUrl
@@ -46,7 +51,10 @@ LeCore.getAcmeUrls(
         // record to disk (or db)
 
         LeCore.getCertificate(
-          {
+          { domainPrivateKeyPem: domainPrivateKeyPem
+          , accountPrivateKeyPem: accountPrivateKeyPem
+          , setChallenge: challengeStore.set
+          , removeChallenge: challengeStore.remove
           }
         , function (err, certs) {
 
@@ -62,6 +70,45 @@ LeCore.getAcmeUrls(
 );
 ```
 
+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
+
+```javascript
+var localCerts = require('localhost.daplie.com-certificates'); // needs default certificates
+var http = require('http');
+var httsp = require('https');
+
+function acmeResponder(req, res) {
+  if (0 !== req.url.indexOf(LeCore.acmeChallengePrefixUrl)) {
+    res.end('Hello World!');
+    return;
+  }
+
+  LeCore.
+}
+
+http.createServer()
+```
+
+Finally, you need an implementation of `challengeStore`:
+
+```javascript
+var challengeCache = {};
+var challengeStore = {
+  set: function (hostname, key, value, cb) {
+    challengeCache[key] = value;
+    cb(null);
+  }
+, get: function (hostname, key, cb) {
+    cb(null, challengeCache[key]);
+  }
+, remove: function (hostname, key, cb) {
+    delete challengeCache[key];
+    cb(null);
+  }
+};
+```
+
 ## API
 
 The Goodies
@@ -90,6 +137,7 @@ Helpers & Stuff
 // Constants
 LeCore.productionServerUrl                // https://acme-v01.api.letsencrypt.org/directory
 LeCore.stagingServerUrl                   // https://acme-staging.api.letsencrypt.org/directory
+LeCore.acmeChallengePrefix                // /.well-known/acme-challenge/
 LeCore.configDir                          // /etc/letsencrypt/
 LeCore.logsDir                            // /var/log/letsencrypt/
 LeCore.workDir                            // /var/lib/letsencrypt/
@@ -130,6 +178,12 @@ LeCore.getAcmeUrls(discoveryUrl, function (err, urls) {
 });
 ```
 
+## Authors
+
+  * ISRG
+  * Anatol Sommer  (https://github.com/anatolsommer)
+  * AJ ONeal <aj@daplie.com> (https://daplie.com)
+
 ## Licence
 
 MPL 2.0
diff --git a/lib/get-certificate.js b/lib/get-certificate.js
index 5073df4..f63cd81 100644
--- a/lib/get-certificate.js
+++ b/lib/get-certificate.js
@@ -9,7 +9,7 @@
 module.exports.create = function (deps) {
   var NOOP=function () {}, log=NOOP;
   var request=require('request');
-  var util=require('./acme-util');
+  var toStandardB64 = deps.leUtils.toStandardB64;
   var importPemPrivateKey = deps.leCrypto.importPemPrivateKey;
   var thumbprinter = deps.leCrypto.thumbprint;
   var generateCsr = deps.leCrypto.generateCsr || deps.leCrypto.generateCSR;
@@ -239,7 +239,7 @@ module.exports.create = function (deps) {
   }
 
   function certBufferToPem(cert) {
-    cert=util.toStandardB64(cert.toString('base64'));
+    cert=toStandardB64(cert.toString('base64'));
     cert=cert.match(/.{1,64}/g).join('\n');
     return '-----BEGIN CERTIFICATE-----\n'+cert+'\n-----END CERTIFICATE-----';
   }
diff --git a/lib/node.js b/lib/node.js
index 2d34c2b..d393f34 100644
--- a/lib/node.js
+++ b/lib/node.js
@@ -6,6 +6,7 @@
 'use strict';
 
 var request = require('request');
+var leUtils = require('./acme-utils');
 var leCrypto = require('./letsencrypt-node-crypto');
 var leForge = require('./letsencrypt-forge');
 var leUrsa;
@@ -36,3 +37,4 @@ Object.keys(leForge).forEach(function (key) {
 
 module.exports.request = request;
 module.exports.leCrypto = leCrypto;
+module.exports.leUtils = leUtils;