bluecrypt-keypairs.js/lib/acme.js

// Copyright 2018-present AJ ONeal. All rights reserved
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
(function (exports) {
'use strict';
/* globals Promise */

var ACME = exports.ACME = {};
var Keypairs = exports.Keypairs || {};
var Enc = exports.Enc || {};
var Crypto = exports.Crypto || {};

ACME.formatPemChain = function formatPemChain(str) {
  return str.trim().replace(/[\r\n]+/g, '\n').replace(/\-\n\-/g, '-\n\n-') + '\n';
};
ACME.splitPemChain = function splitPemChain(str) {
  return str.trim().split(/[\r\n]{2,}/g).map(function (str) {
    return str + '\n';
  });
};


// http-01: GET https://example.org/.well-known/acme-challenge/{{token}} => {{keyAuth}}
// dns-01: TXT _acme-challenge.example.org. => "{{urlSafeBase64(sha256(keyAuth))}}"
ACME.challengePrefixes = {
  'http-01': '/.well-known/acme-challenge'
, 'dns-01': '_acme-challenge'
};
ACME.challengeTests = {
  'http-01': function (me, auth) {
    var url = 'http://' + auth.hostname + ACME.challengePrefixes['http-01'] + '/' + auth.token;
    return me._request({ method: 'GET', url: url }).then(function (resp) {
      var err;

      // TODO limit the number of bytes that are allowed to be downloaded
      if (auth.keyAuthorization === resp.body.toString('utf8').trim()) {
        return true;
      }

      err = new Error(
        "Error: Failed HTTP-01 Pre-Flight / Dry Run.\n"
      + "curl '" + url + "'\n"
      + "Expected: '" + auth.keyAuthorization + "'\n"
      + "Got: '" + resp.body + "'\n"
      + "See https://git.coolaj86.com/coolaj86/acme-v2.js/issues/4"
      );
      err.code = 'E_FAIL_DRY_CHALLENGE';
      return Promise.reject(err);
    });
  }
, 'dns-01': function (me, auth) {
    // remove leading *. on wildcard domains
    return me.dig({
      type: 'TXT'
    , name: auth.dnsHost
    }).then(function (ans) {
      var err;

      if (ans.answer.some(function (txt) {
        return auth.dnsAuthorization === txt.data[0];
      })) {
        return true;
      }

      err = new Error(
        "Error: Failed DNS-01 Pre-Flight Dry Run.\n"
      + "dig TXT '" + auth.dnsHost + "' does not return '" + auth.dnsAuthorization + "'\n"
      + "See https://git.coolaj86.com/coolaj86/acme-v2.js/issues/4"
      );
      err.code = 'E_FAIL_DRY_CHALLENGE';
      return Promise.reject(err);
    });
  }
};

ACME._directory = function (me) {
  // GET-as-GET ok
  return me._request({ method: 'GET', url: me.directoryUrl, json: true });
};
ACME._getNonce = function (me) {
  // GET-as-GET, HEAD-as-HEAD ok
  if (me._nonce) { return new Promise(function (resolve) { resolve(me._nonce); return; }); }
  return me._request({ method: 'HEAD', url: me._directoryUrls.newNonce }).then(function (resp) {
    me._nonce = resp.toJSON().headers['replay-nonce'];
    return me._nonce;
  });
};
// ACME RFC Section 7.3 Account Creation
/*
 {
   "protected": base64url({
     "alg": "ES256",
     "jwk": {...},
     "nonce": "6S8IqOGY7eL2lsGoTZYifg",
     "url": "https://example.com/acme/new-account"
   }),
   "payload": base64url({
     "termsOfServiceAgreed": true,
     "onlyReturnExisting": false,
     "contact": [
       "mailto:cert-admin@example.com",
       "mailto:admin@example.com"
     ]
   }),
   "signature": "RZPOnYoPs1PhjszF...-nh6X1qtOFPB519I"
 }
*/
ACME._registerAccount = function (me, options) {
  if (me.debug) { console.debug('[acme-v2] accounts.create'); }

  return ACME._getNonce(me).then(function () {
    return new Promise(function (resolve, reject) {

      function agree(tosUrl) {
        var err;
        if (me._tos !== tosUrl) {
          err = new Error("You must agree to the ToS at '" + me._tos + "'");
          err.code = "E_AGREE_TOS";
          reject(err);
          return;
        }

        var jwk = options.accountKeypair.privateKeyJwk;
        var p;
        if (jwk) {
          p = Promise.resolve({ private: jwk, public: Keypairs.neuter(jwk) });
        } else {
          p = Keypairs.import({ pem: options.accountKeypair.privateKeyPem });
        }
        return p.then(function (pair) {
          if (pair.public.kid) {
            pair = JSON.parse(JSON.stringify(pair));
            delete pair.public.kid;
            delete pair.private.kid;
          }
          return pair;
        }).then(function (pair) {
          var contact;
          if (options.contact) {
            contact = options.contact.slice(0);
          } else if (options.email) {
            contact = [ 'mailto:' + options.email ];
          }
          var body = {
            termsOfServiceAgreed: tosUrl === me._tos
          , onlyReturnExisting: false
          , contact: contact
          };
          if (options.externalAccount) {
            body.externalAccountBinding = me.RSA.signJws(
              // TODO is HMAC the standard, or is this arbitrary?
              options.externalAccount.secret
            , undefined
            , { alg: options.externalAccount.alg || "HS256"
              , kid: options.externalAccount.id
              , url: me._directoryUrls.newAccount
              }
            , Buffer.from(JSON.stringify(pair.public))
            );
          }
          var payload = JSON.stringify(body);
          var jws = Keypairs.signJws(
            options.accountKeypair
          , undefined
          , { nonce: me._nonce
            , alg: (me._alg || 'RS256')
            , url: me._directoryUrls.newAccount
            , jwk: pair.public
            }
          , Buffer.from(payload)
          );

          delete jws.header;
          if (me.debug) { console.debug('[acme-v2] accounts.create JSON body:'); }
          if (me.debug) { console.debug(jws); }
          me._nonce = null;
          return me._request({
            method: 'POST'
          , url: me._directoryUrls.newAccount
          , headers: { 'Content-Type': 'application/jose+json' }
          , json: jws
          }).then(function (resp) {
            var account = resp.body;

            if (2 !== Math.floor(resp.statusCode / 100)) {
              throw new Error('account error: ' + JSON.stringify(body));
            }

            me._nonce = resp.toJSON().headers['replay-nonce'];
            var location = resp.toJSON().headers.location;
            // the account id url
            me._kid = location;
            if (me.debug) { console.debug('[DEBUG] new account location:'); }
            if (me.debug) { console.debug(location); }
            if (me.debug) { console.debug(resp.toJSON()); }

            /*
            {
              contact: ["mailto:jon@example.com"],
              orders: "https://some-url",
              status: 'valid'
            }
            */
            if (!account) { account = { _emptyResponse: true, key: {} }; }
            // https://git.coolaj86.com/coolaj86/acme-v2.js/issues/8
            if (!account.key) { account.key = {}; }
            account.key.kid = me._kid;
            return account;
          }).then(resolve, reject);
        });
      }

      if (me.debug) { console.debug('[acme-v2] agreeToTerms'); }
      if (1 === options.agreeToTerms.length) {
        // newer promise API
        return options.agreeToTerms(me._tos).then(agree, reject);
      }
      else if (2 === options.agreeToTerms.length) {
        // backwards compat cb API
        return options.agreeToTerms(me._tos, function (err, tosUrl) {
          if (!err) { agree(tosUrl); return; }
          reject(err);
        });
      }
      else {
        reject(new Error('agreeToTerms has incorrect function signature.'
          + ' Should be fn(tos) { return Promise<tos>; }'));
      }
    });
  });
};
/*
 POST /acme/new-order HTTP/1.1
 Host: example.com
 Content-Type: application/jose+json

 {
   "protected": base64url({
     "alg": "ES256",
     "kid": "https://example.com/acme/acct/1",
     "nonce": "5XJ1L3lEkMG7tR6pA00clA",
     "url": "https://example.com/acme/new-order"
   }),
   "payload": base64url({
     "identifiers": [{"type:"dns","value":"example.com"}],
     "notBefore": "2016-01-01T00:00:00Z",
     "notAfter": "2016-01-08T00:00:00Z"
   }),
   "signature": "H6ZXtGjTZyUnPeKn...wEA4TklBdh3e454g"
 }
*/
ACME._getChallenges = function (me, options, auth) {
  if (me.debug) { console.debug('\n[DEBUG] getChallenges\n'); }
  // TODO POST-as-GET
  return me._request({ method: 'GET', url: auth, json: true }).then(function (resp) {
    return resp.body;
  });
};
ACME._wait = function wait(ms) {
  return new Promise(function (resolve) {
    setTimeout(resolve, (ms || 1100));
  });
};

ACME._testChallengeOptions = function () {
  var chToken = ACME._prnd(16);
  return [
    {
      "type": "http-01",
      "status": "pending",
      "url": "https://acme-staging-v02.example.com/0",
      "token": "test-" + chToken + "-0"
    }
  , {
      "type": "dns-01",
      "status": "pending",
      "url": "https://acme-staging-v02.example.com/1",
      "token": "test-" + chToken + "-1",
      "_wildcard": true
    }
  , {
      "type": "tls-sni-01",
      "status": "pending",
      "url": "https://acme-staging-v02.example.com/2",
      "token": "test-" + chToken + "-2"
    }
  , {
      "type": "tls-alpn-01",
      "status": "pending",
      "url": "https://acme-staging-v02.example.com/3",
      "token": "test-" + chToken + "-3"
    }
  ];
};
ACME._testChallenges = function (me, options) {
  if (me.skipChallengeTest) {
    return Promise.resolve();
  }

  var CHECK_DELAY = 0;
  return Promise.all(options.domains.map(function (identifierValue) {
    // TODO we really only need one to pass, not all to pass
    var challenges = ACME._testChallengeOptions();
    if (identifierValue.includes("*")) {
      challenges = challenges.filter(function (ch) { return ch._wildcard; });
    }

    var challenge = ACME._chooseChallenge(options, { challenges: challenges });
    if (!challenge) {
      // For example, wildcards require dns-01 and, if we don't have that, we have to bail
      var enabled = options.challengeTypes.join(', ') || 'none';
      var suitable = challenges.map(function (r) { return r.type; }).join(', ') || 'none';
      return Promise.reject(new Error(
        "None of the challenge types that you've enabled ( " + enabled + " )"
          + " are suitable for validating the domain you've selected (" + identifierValue + ")."
          + " You must enable one of ( " + suitable + " )."
      ));
    }
    if ('dns-01' === challenge.type) {
      // Give the nameservers a moment to propagate
      CHECK_DELAY = 1.5 * 1000;
    }

    return Promise.resolve().then(function () {
      var results = {
        identifier: {
          type: "dns"
        , value: identifierValue.replace(/^\*\./, '')
        }
      , challenges: [ challenge ]
      , expires: new Date(Date.now() + (60 * 1000)).toISOString()
      , wildcard: identifierValue.includes('*.') || undefined
      };
      var dryrun = true;
      var auth = ACME._challengeToAuth(me, options, results, challenge, dryrun);
      return ACME._setChallenge(me, options, auth).then(function () {
        return auth;
      });
    });
  })).then(function (auths) {
    return ACME._wait(CHECK_DELAY).then(function () {
      return Promise.all(auths.map(function (auth) {
        return ACME.challengeTests[auth.type](me, auth);
      }));
    });
  });
};
ACME._chooseChallenge = function(options, results) {
  // For each of the challenge types that we support
  var challenge;
  options.challengeTypes.some(function (chType) {
    // And for each of the challenge types that are allowed
    return results.challenges.some(function (ch) {
      // Check to see if there are any matches
      if (ch.type === chType) {
        challenge = ch;
        return true;
      }
    });
  });

  return challenge;
};
ACME._challengeToAuth = function (me, options, request, challenge, dryrun) {
  // we don't poison the dns cache with our dummy request
  var dnsPrefix = ACME.challengePrefixes['dns-01'];
  if (dryrun) {
    dnsPrefix = dnsPrefix.replace('acme-challenge', 'greenlock-dryrun-' + ACME._prnd(4));
  }

  var auth = {};

  // straight copy from the new order response
  // { identifier, status, expires, challenges, wildcard }
  Object.keys(request).forEach(function (key) {
    auth[key] = request[key];
  });

  // copy from the challenge we've chosen
  // { type, status, url, token }
  // (note the duplicate status overwrites the one above, but they should be the same)
  Object.keys(challenge).forEach(function (key) {
    // don't confused devs with the id url
    auth[key] = challenge[key];
  });

  // batteries-included helpers
  auth.hostname = auth.identifier.value;
  // because I'm not 100% clear if the wildcard identifier does or doesn't have the leading *. in all cases
  auth.altname = ACME._untame(auth.identifier.value, auth.wildcard);
  auth.thumbprint = me.RSA.thumbprint(options.accountKeypair);
  //   keyAuthorization = token || '.' || base64url(JWK_Thumbprint(accountKey))
  auth.keyAuthorization = challenge.token + '.' + auth.thumbprint;
  // conflicts with ACME challenge id url is already in use, so we call this challengeUrl instead
  auth.challengeUrl = 'http://' + auth.identifier.value + ACME.challengePrefixes['http-01'] + '/' + auth.token;
  auth.dnsHost = dnsPrefix + '.' + auth.hostname.replace('*.', '');

  return Crypto._sha('sha256', auth.keyAuthorization).then(function (hash) {
    auth.dnsAuthorization = hash;
    return auth;
  });
};

ACME._untame = function (name, wild) {
  if (wild) { name = '*.' + name.replace('*.', ''); }
  return name;
};

// https://tools.ietf.org/html/draft-ietf-acme-acme-10#section-7.5.1
ACME._postChallenge = function (me, options, auth) {
  var RETRY_INTERVAL = me.retryInterval || 1000;
  var DEAUTH_INTERVAL = me.deauthWait || 10 * 1000;
  var MAX_POLL = me.retryPoll || 8;
  var MAX_PEND = me.retryPending || 4;
  var count = 0;

  var altname = ACME._untame(auth.identifier.value, auth.wildcard);

  /*
   POST /acme/authz/1234 HTTP/1.1
   Host: example.com
   Content-Type: application/jose+json

   {
     "protected": base64url({
       "alg": "ES256",
       "kid": "https://example.com/acme/acct/1",
       "nonce": "xWCM9lGbIyCgue8di6ueWQ",
       "url": "https://example.com/acme/authz/1234"
     }),
     "payload": base64url({
       "status": "deactivated"
     }),
     "signature": "srX9Ji7Le9bjszhu...WTFdtujObzMtZcx4"
   }
   */
  function deactivate() {
    var jws = me.RSA.signJws(
      options.accountKeypair
    , undefined
    , { nonce: me._nonce, alg: (me._alg || 'RS256'), url: auth.url, kid: me._kid }
    , Buffer.from(JSON.stringify({ "status": "deactivated" }))
    );
    me._nonce = null;
    return me._request({
      method: 'POST'
    , url: auth.url
    , headers: { 'Content-Type': 'application/jose+json' }
    , json: jws
    }).then(function (resp) {
      if (me.debug) { console.debug('[acme-v2.js] deactivate:'); }
      if (me.debug) { console.debug(resp.headers); }
      if (me.debug) { console.debug(resp.body); }
      if (me.debug) { console.debug(); }

      me._nonce = resp.toJSON().headers['replay-nonce'];
      if (me.debug) { console.debug('deactivate challenge: resp.body:'); }
      if (me.debug) { console.debug(resp.body); }
      return ACME._wait(DEAUTH_INTERVAL);
    });
  }

  function pollStatus() {
    if (count >= MAX_POLL) {
      return Promise.reject(new Error(
        "[acme-v2] stuck in bad pending/processing state for '" + altname + "'"
      ));
    }

    count += 1;

    if (me.debug) { console.debug('\n[DEBUG] statusChallenge\n'); }
    // TODO POST-as-GET
    return me._request({ method: 'GET', url: auth.url, json: true }).then(function (resp) {
      if ('processing' === resp.body.status) {
        if (me.debug) { console.debug('poll: again'); }
        return ACME._wait(RETRY_INTERVAL).then(pollStatus);
      }

      // This state should never occur
      if ('pending' === resp.body.status) {
        if (count >= MAX_PEND) {
          return ACME._wait(RETRY_INTERVAL).then(deactivate).then(respondToChallenge);
        }
        if (me.debug) { console.debug('poll: again'); }
        return ACME._wait(RETRY_INTERVAL).then(respondToChallenge);
      }

      if ('valid' === resp.body.status) {
        if (me.debug) { console.debug('poll: valid'); }

        try {
          if (1 === options.removeChallenge.length) {
            options.removeChallenge(auth).then(function () {}, function () {});
          } else if (2 === options.removeChallenge.length) {
            options.removeChallenge(auth, function (err) { return err; });
          } else {
            if (!ACME._removeChallengeWarn) {
              console.warn("Please update to acme-v2 removeChallenge(options) <Promise> or removeChallenge(options, cb).");
              console.warn("The API has been changed for compatibility with all ACME / Let's Encrypt challenge types.");
              ACME._removeChallengeWarn = true;
            }
            options.removeChallenge(auth.request.identifier, auth.token, function () {});
          }
        } catch(e) {}
        return resp.body;
      }

      var errmsg;
      if (!resp.body.status) {
        errmsg = "[acme-v2] (E_STATE_EMPTY) empty challenge state for '" + altname + "':";
      }
      else if ('invalid' === resp.body.status) {
        errmsg = "[acme-v2] (E_STATE_INVALID) challenge state for '" + altname + "': '" + resp.body.status + "'";
      }
      else {
        errmsg = "[acme-v2] (E_STATE_UKN) challenge state for '" + altname + "': '" + resp.body.status + "'";
      }

      return Promise.reject(new Error(errmsg));
    });
  }

  function respondToChallenge() {
    var jws = me.RSA.signJws(
      options.accountKeypair
    , undefined
    , { nonce: me._nonce, alg: (me._alg || 'RS256'), url: auth.url, kid: me._kid }
    , Buffer.from(JSON.stringify({ }))
    );
    me._nonce = null;
    return me._request({
      method: 'POST'
    , url: auth.url
    , headers: { 'Content-Type': 'application/jose+json' }
    , json: jws
    }).then(function (resp) {
      if (me.debug) { console.debug('[acme-v2.js] challenge accepted!'); }
      if (me.debug) { console.debug(resp.headers); }
      if (me.debug) { console.debug(resp.body); }
      if (me.debug) { console.debug(); }

      me._nonce = resp.toJSON().headers['replay-nonce'];
      if (me.debug) { console.debug('respond to challenge: resp.body:'); }
      if (me.debug) { console.debug(resp.body); }
      return ACME._wait(RETRY_INTERVAL).then(pollStatus);
    });
  }

  return respondToChallenge();
};
ACME._setChallenge = function (me, options, auth) {
  return new Promise(function (resolve, reject) {
    try {
      if (1 === options.setChallenge.length) {
        options.setChallenge(auth).then(resolve).catch(reject);
      } else if (2 === options.setChallenge.length) {
        options.setChallenge(auth, function (err) {
          if(err) { reject(err); } else { resolve(); }
        });
      } else {
        var challengeCb = function(err) {
          if(err) { reject(err); } else { resolve(); }
        };
        // for backwards compat adding extra keys without changing params length
        Object.keys(auth).forEach(function (key) {
          challengeCb[key] = auth[key];
        });
        if (!ACME._setChallengeWarn) {
          console.warn("Please update to acme-v2 setChallenge(options) <Promise> or setChallenge(options, cb).");
          console.warn("The API has been changed for compatibility with all ACME / Let's Encrypt challenge types.");
          ACME._setChallengeWarn = true;
        }
        options.setChallenge(auth.identifier.value, auth.token, auth.keyAuthorization, challengeCb);
      }
    } catch(e) {
      reject(e);
    }
  }).then(function () {
    // TODO: Do we still need this delay? Or shall we leave it to plugins to account for themselves?
    var DELAY = me.setChallengeWait || 500;
    if (me.debug) { console.debug('\n[DEBUG] waitChallengeDelay %s\n', DELAY); }
    return ACME._wait(DELAY);
  });
};
ACME._finalizeOrder = function (me, options, validatedDomains) {
  if (me.debug) { console.debug('finalizeOrder:'); }
  var csr = me.RSA.generateCsrWeb64(options.domainKeypair, validatedDomains);
  var body = { csr: csr };
  var payload = JSON.stringify(body);

  function pollCert() {
    var jws = me.RSA.signJws(
      options.accountKeypair
    , undefined
    , { nonce: me._nonce, alg: (me._alg || 'RS256'), url: me._finalize, kid: me._kid }
    , Buffer.from(payload)
    );

    if (me.debug) { console.debug('finalize:', me._finalize); }
    me._nonce = null;
    return me._request({
      method: 'POST'
    , url: me._finalize
    , headers: { 'Content-Type': 'application/jose+json' }
    , json: jws
    }).then(function (resp) {
      // https://tools.ietf.org/html/draft-ietf-acme-acme-12#section-7.1.3
      // Possible values are: "pending" => ("invalid" || "ready") => "processing" => "valid"
      me._nonce = resp.toJSON().headers['replay-nonce'];

      if (me.debug) { console.debug('order finalized: resp.body:'); }
      if (me.debug) { console.debug(resp.body); }

      if ('valid' === resp.body.status) {
        me._expires = resp.body.expires;
        me._certificate = resp.body.certificate;

        return resp.body; // return order
      }

      if ('processing' === resp.body.status) {
        return ACME._wait().then(pollCert);
      }

      if (me.debug) { console.debug("Error: bad status:\n" + JSON.stringify(resp.body, null, 2)); }

      if ('pending' === resp.body.status) {
        return Promise.reject(new Error(
          "Did not finalize order: status 'pending'."
        + " Best guess: You have not accepted at least one challenge for each domain:\n"
        + "Requested: '" + options.domains.join(', ') + "'\n"
        + "Validated: '" + validatedDomains.join(', ') + "'\n"
        + JSON.stringify(resp.body, null, 2)
        ));
      }

      if ('invalid' === resp.body.status) {
        return Promise.reject(new Error(
          "Did not finalize order: status 'invalid'."
        + " Best guess: One or more of the domain challenges could not be verified"
        + " (or the order was canceled).\n"
        + "Requested: '" + options.domains.join(', ') + "'\n"
        + "Validated: '" + validatedDomains.join(', ') + "'\n"
        + JSON.stringify(resp.body, null, 2)
        ));
      }

      if ('ready' === resp.body.status) {
        return Promise.reject(new Error(
          "Did not finalize order: status 'ready'."
        + " Hmmm... this state shouldn't be possible here. That was the last state."
        + " This one should at least be 'processing'.\n"
        + "Requested: '" + options.domains.join(', ') + "'\n"
        + "Validated: '" + validatedDomains.join(', ') + "'\n"
        + JSON.stringify(resp.body, null, 2) + "\n\n"
        + "Please open an issue at https://git.coolaj86.com/coolaj86/acme-v2.js"
        ));
      }

      return Promise.reject(new Error(
        "Didn't finalize order: Unhandled status '" + resp.body.status + "'."
      + " This is not one of the known statuses...\n"
      + "Requested: '" + options.domains.join(', ') + "'\n"
      + "Validated: '" + validatedDomains.join(', ') + "'\n"
      + JSON.stringify(resp.body, null, 2) + "\n\n"
      + "Please open an issue at https://git.coolaj86.com/coolaj86/acme-v2.js"
      ));
    });
  }

  return pollCert();
};
ACME._getCertificate = function (me, options) {
  if (me.debug) { console.debug('[acme-v2] DEBUG get cert 1'); }

  // Lot's of error checking to inform the user of mistakes
  if (!(options.challengeTypes||[]).length) {
    options.challengeTypes = Object.keys(options.challenges||{});
  }
  if (!options.challengeTypes.length) {
    options.challengeTypes = [ options.challengeType ].filter(Boolean);
  }
  if (options.challengeType) {
    options.challengeTypes.sort(function (a, b) {
      if (a === options.challengeType) { return -1; }
      if (b === options.challengeType) { return 1; }
      return 0;
    });
    if (options.challengeType !== options.challengeTypes[0]) {
      return Promise.reject(new Error("options.challengeType is '" + options.challengeType + "',"
        + " which does not exist in the supplied types '" + options.challengeTypes.join(',') + "'"));
    }
  }
  // TODO check that all challengeTypes are represented in challenges
  if (!options.challengeTypes.length) {
    return Promise.reject(new Error("options.challengeTypes (string array) must be specified"
      + " (and in order of preferential priority)."));
  }
  if (!(options.domains && options.domains.length)) {
    return Promise.reject(new Error("options.domains must be a list of string domain names,"
    + " with the first being the subject of the domain (or options.subject must specified)."));
  }

  // It's just fine if there's no account, we'll go get the key id we need via the public key
  if (!me._kid) {
    if (options.accountKid || options.account && options.account.kid) {
      me._kid = options.accountKid || options.account.kid;
    } else {
      //return Promise.reject(new Error("must include KeyID"));
      // This is an idempotent request. It'll return the same account for the same public key.
      return ACME._registerAccount(me, options).then(function () {
        // start back from the top
        return ACME._getCertificate(me, options);
      });
    }
  }

  // Do a little dry-run / self-test
  return ACME._testChallenges(me, options).then(function () {
    if (me.debug) { console.debug('[acme-v2] certificates.create'); }
    return ACME._getNonce(me).then(function () {
      var body = {
        // raw wildcard syntax MUST be used here
        identifiers: options.domains.sort(function (a, b) {
          // the first in the list will be the subject of the certificate, I believe (and hope)
          if (!options.subject) { return 0; }
          if (options.subject === a) { return -1; }
          if (options.subject === b) { return 1; }
          return 0;
        }).map(function (hostname) {
          return { type: "dns", value: hostname };
        })
        //, "notBefore": "2016-01-01T00:00:00Z"
        //, "notAfter": "2016-01-08T00:00:00Z"
      };

      var payload = JSON.stringify(body);
      // determine the signing algorithm to use in protected header // TODO isn't that handled by the signer?
      me._kty = (options.accountKeypair.privateKeyJwk && options.accountKeypair.privateKeyJwk.kty || 'RSA');
      me._alg = ('EC' === me._kty) ? 'ES256' : 'RS256'; // TODO vary with bitwidth of key (if not handled)
      var jws = me.RSA.signJws(
        options.accountKeypair
      , undefined
      , { nonce: me._nonce, alg: me._alg, url: me._directoryUrls.newOrder, kid: me._kid }
      , Buffer.from(payload, 'utf8')
      );

      if (me.debug) { console.debug('\n[DEBUG] newOrder\n'); }
      me._nonce = null;
      return me._request({
        method: 'POST'
      , url: me._directoryUrls.newOrder
      , headers: { 'Content-Type': 'application/jose+json' }
      , json: jws
      }).then(function (resp) {
        me._nonce = resp.toJSON().headers['replay-nonce'];
        var location = resp.toJSON().headers.location;
        var setAuths;
        var auths = [];
        if (me.debug) { console.debug(location); } // the account id url
        if (me.debug) { console.debug(resp.toJSON()); }
        me._authorizations = resp.body.authorizations;
        me._order = location;
        me._finalize = resp.body.finalize;
        //if (me.debug) console.debug('[DEBUG] finalize:', me._finalize); return;

        if (!me._authorizations) {
          return Promise.reject(new Error(
            "[acme-v2.js] authorizations were not fetched for '" + options.domains.join() + "':\n"
            + JSON.stringify(resp.body)
          ));
        }
        if (me.debug) { console.debug("[acme-v2] POST newOrder has authorizations"); }
        setAuths = me._authorizations.slice(0);

        function setNext() {
          var authUrl = setAuths.shift();
          if (!authUrl) { return; }

          return ACME._getChallenges(me, options, authUrl).then(function (results) {
            // var domain = options.domains[i]; // results.identifier.value

            // If it's already valid, we're golden it regardless
            if (results.challenges.some(function (ch) { return 'valid' === ch.status; })) {
              return setNext();
            }

            var challenge = ACME._chooseChallenge(options, results);
            if (!challenge) {
              // For example, wildcards require dns-01 and, if we don't have that, we have to bail
              return Promise.reject(new Error(
                "Server didn't offer any challenge we can handle for '" + options.domains.join() + "'."
              ));
            }

            return ACME._challengeToAuth(me, options, results, challenge, false).then(function (auth) {
              auths.push(auth);
              return ACME._setChallenge(me, options, auth).then(setNext);
            });
          });
        }

        function challengeNext() {
          var auth = auths.shift();
          if (!auth) { return; }
          return ACME._postChallenge(me, options, auth).then(challengeNext);
        }

        // First we set every challenge
        // Then we ask for each challenge to be checked
        // Doing otherwise would potentially cause us to poison our own DNS cache with misses
        return setNext().then(challengeNext).then(function () {
          if (me.debug) { console.debug("[getCertificate] next.then"); }
          var validatedDomains = body.identifiers.map(function (ident) {
            return ident.value;
          });

          return ACME._finalizeOrder(me, options, validatedDomains);
        }).then(function (order) {
          if (me.debug) { console.debug('acme-v2: order was finalized'); }
          // TODO POST-as-GET
          return me._request({ method: 'GET', url: me._certificate, json: true }).then(function (resp) {
            if (me.debug) { console.debug('acme-v2: csr submitted and cert received:'); }
            // https://github.com/certbot/certbot/issues/5721
            var certsarr = ACME.splitPemChain(ACME.formatPemChain((resp.body||'')));
            //  cert, chain, fullchain, privkey, /*TODO, subject, altnames, issuedAt, expiresAt */
            var certs = {
              expires: order.expires
            , identifiers: order.identifiers
            //, authorizations: order.authorizations
            , cert: certsarr.shift()
            //, privkey: privkeyPem
            , chain: certsarr.join('\n')
            };
            if (me.debug) { console.debug(certs); }
            return certs;
          });
        });
      });
    });
  });
};

ACME.create = function create(me) {
  if (!me) { me = {}; }
  // me.debug = true;
  me.challengePrefixes = ACME.challengePrefixes;
  me.RSA = me.RSA || require('rsa-compat').RSA;
  //me.Keypairs = me.Keypairs || require('keypairs');
  me.request = me.request || require('@coolaj86/urequest');
  if (!me.dig) {
    me.dig = function (query) {
      // TODO use digd.js
      return new Promise(function (resolve, reject) {
        var dns = require('dns');
        dns.resolveTxt(query.name, function (err, records) {
          if (err) { reject(err); return; }

          resolve({
            answer: records.map(function (rr) {
              return {
                data: rr
              };
            })
          });
        });
      });
    };
  }
  me.promisify = me.promisify || require('util').promisify /*node v8+*/ || require('bluebird').promisify /*node v6*/;


  if ('function' !== typeof me._request) {
    // MUST have a User-Agent string (see node.js version)
    me._request = function (opts) {
      return window.fetch(opts.url, opts).then(function (resp) {
        return resp.json().then(function (json) {
          var headers = {};
          Array.from(resp.headers.entries()).forEach(function (h) { headers[h[0]] = h[1]; });
          return { headers: headers , body: json };
        });
      });
    };
  }

  me.init = function (_directoryUrl) {
    me.directoryUrl = me.directoryUrl || _directoryUrl;
    return ACME._directory(me).then(function (resp) {
      me._directoryUrls = resp.body;
      me._tos = me._directoryUrls.meta.termsOfService;
      return me._directoryUrls;
    });
  };
  me.accounts = {
    create: function (options) {
      return ACME._registerAccount(me, options);
    }
  };
  me.certificates = {
    create: function (options) {
      return ACME._getCertificate(me, options);
    }
  };
  return me;
};

ACME._toWebsafeBase64 = function (b64) {
  return b64.replace(/\+/g, "-").replace(/\//g, "_").replace(/=/g,"");
};

// In v8 this is crypto random, but we're just using it for pseudorandom
ACME._prnd = function (n) {
  var rnd = '';
  while (rnd.length / 2 < n) {
    var num = Math.random().toString().substr(2);
    if (num.length % 2) {
      num = '0' + num;
    }
    var pairs = num.match(/(..?)/g);
    rnd += pairs.map(ACME._toHex).join('');
  }
  return rnd.substr(0, n*2);
};
ACME._toHex = function (pair) {
  return parseInt(pair, 10).toString(16);
};

Enc.bufToUrlBase64 = function (u8) {
  return Enc.bufToBase64(u8)
    .replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '');
};
Enc.bufToBase64 = function (u8) {
  var bin = '';
  u8.forEach(function (i) {
    bin += String.fromCharCode(i);
  });
  return btoa(bin);
};

Crypto._sha = function (sha, str) {
  var encoder = new TextEncoder();
  var data = encoder.encode(str);
  sha = 'SHA-' + sha.replace(/^sha-?/i, '');
  return window.crypto.subtle.digest(sha, data).then(function (hash) {
    return Enc.bufToUrlBase64(new Uint8Array(hash));
  });
};

}('undefined' === typeof window ? module.exports : window));