diff --git a/app.js b/app.js
index 1185815..c861b5b 100644
--- a/app.js
+++ b/app.js
@@ -151,10 +151,13 @@
       ev.stopPropagation();
       var domains = ($('.js-domains').value||'example.com').split(/[, ]+/g);
       var privJwk = JSON.parse($('.js-jwk').innerText).private;
-      return CSR({ jwk: privJwk, domains: domains }).then(function (web64) {
+      return CSR({ jwk: privJwk, domains: domains }).then(function (pem) {
         // Verify with https://www.sslshopper.com/csr-decoder.html
-        console.log('urlBase64 CSR:');
-        console.log(web64);
+        console.log('CSR:');
+        console.log(pem);
+
+        console.log('CSR info:');
+        console.log(CSR._info(pem));
       });
     });
 
diff --git a/index.html b/index.html
index 4379cdb..5978ffd 100644
--- a/index.html
+++ b/index.html
@@ -128,6 +128,7 @@
     <script src="./lib/ecdsa.js"></script>
     <script src="./lib/rsa.js"></script>
     <script src="./lib/keypairs.js"></script>
+    <script src="./lib/asn1-parser.js"></script>
     <script src="./lib/csr.js"></script>
     <script src="./lib/acme.js"></script>
     <script src="./app.js"></script>
diff --git a/lib/acme.js b/lib/acme.js
index 87668c4..ea7113a 100644
--- a/lib/acme.js
+++ b/lib/acme.js
@@ -8,6 +8,7 @@
 
 var ACME = exports.ACME = {};
 //var Keypairs = exports.Keypairs || {};
+//var CSR = exports.CSR;
 var Enc = exports.Enc || {};
 var Crypto = exports.Crypto || {};
 
@@ -670,6 +671,14 @@ ACME._getCertificate = function (me, options) {
     return Promise.reject(new Error("options.challengeTypes (string array) must be specified"
       + " (and in order of preferential priority)."));
   }
+  if (options.csr) {
+    // TODO validate csr signature
+    options._csr = me.CSR._info(options.csr);
+    options.domains = options._csr.altnames;
+    if (options._csr.subject !== options.domains[0]) {
+      return Promise.reject(new Error("certificate subject (commonName) does not match first altname (SAN)"));
+    }
+  }
   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 certificate (or options.subject must specified)."));
@@ -818,8 +827,8 @@ ACME._getCertificate = function (me, options) {
   });
 };
 ACME._generateCsrWeb64 = function (me, options, validatedDomains) {
-  return ACME._importKeypair(me, options.domainKeypair).then(function (/*pair*/) {
-    return me.Keypairs.generateCsr(options.domainKeypair, validatedDomains).then(function (der) {
+  return ACME._importKeypair(me, options.domainKeypair).then(function (pair) {
+    return me.CSR({ jwk: pair.private, domains: validatedDomains, encoding: 'der' }).then(function (der) {
       return Enc.bufToUrlBase64(der);
     });
   });
@@ -830,6 +839,7 @@ ACME.create = function create(me) {
   // me.debug = true;
   me.challengePrefixes = ACME.challengePrefixes;
   me.Keypairs = me.Keypairs || me.RSA || require('rsa-compat').RSA;
+  me.CSR = me.CSR || require('CSR').CSR;
   me._nonces = [];
   me._canCheck = {};
   if (!me._baseUrl) {
diff --git a/lib/asn1-parser.js b/lib/asn1-parser.js
index 82f7cd0..9314aa3 100644
--- a/lib/asn1-parser.js
+++ b/lib/asn1-parser.js
@@ -125,7 +125,7 @@ PEM.parseBlock = PEM.parseBlock || function (str) {
   var der = str.split(/\n/).filter(function (line) {
     return !/-----/.test(line);
   }).join('');
-  return { der: Enc.base64ToBuf(der) };
+  return { bytes: Enc.base64ToBuf(der) };
 };
 
 Enc.base64ToBuf = function (b64) {
diff --git a/lib/csr.js b/lib/csr.js
index 3eb75cd..4f6d61b 100644
--- a/lib/csr.js
+++ b/lib/csr.js
@@ -155,6 +155,100 @@ X509.packCsr = function (asn1pubkey, domains) {
   );
 };
 
+// TODO finish this later
+// we want to parse the domains, the public key, and verify the signature
+CSR._info = function (der) {
+  // standard base64 PEM
+  if ('string' === typeof der && '-' === der[0]) {
+    der = PEM.parseBlock(der).bytes;
+  }
+  // jose urlBase64 not-PEM
+  if ('string' === typeof der) {
+    der = Enc.base64ToBuf(der);
+  }
+  // not supporting binary-encoded bas64
+  var c = ASN1.parse(der);
+  var kty;
+  // A cert has 3 parts: cert, signature meta, signature
+  if (c.children.length !== 3) {
+    throw new Error("doesn't look like a certificate request: expected 3 parts of header");
+  }
+  var sig = c.children[2];
+  if (sig.children.length) {
+    // ASN1/X509 EC
+    sig = sig.children[0];
+    sig = ASN1('30', ASN1.UInt(Enc.bufToHex(sig.children[0].value)), ASN1.UInt(Enc.bufToHex(sig.children[1].value)));
+    sig = Enc.hexToBuf(sig);
+    kty = 'EC';
+  } else {
+    // Raw RSA Sig
+    sig = sig.value;
+    kty = 'RSA';
+  }
+  //c.children[1]; // signature type
+  var req = c.children[0];
+  // TODO utf8
+  if (4 !== req.children.length) {
+    throw new Error("doesn't look like a certificate request: expected 4 parts to request");
+  }
+  // 0 null
+  // 1 commonName / subject
+  var sub = Enc.bufToBin(req.children[1].children[0].children[0].children[1].value);
+  // 3 public key (type, key)
+  //console.log('oid', Enc.bufToHex(req.children[2].children[0].children[0].value));
+  var pub;
+  // TODO reuse ASN1 parser for these?
+  if ('EC' === kty) {
+    // throw away compression byte
+    pub = req.children[2].children[1].value.slice(1);
+    pub = { kty: kty, x: pub.slice(0, 32), y: pub.slice(32) };
+    while (0 === pub.x[0]) { pub.x = pub.x.slice(1); }
+    while (0 === pub.y[0]) { pub.y = pub.y.slice(1); }
+    if ((pub.x.length || pub.x.byteLength) > 48) {
+      pub.crv = 'P-521';
+    } else if ((pub.x.length || pub.x.byteLength) > 32) {
+      pub.crv = 'P-384';
+    } else {
+      pub.crv = 'P-256';
+    }
+    pub.x = Enc.bufToUrlBase64(pub.x);
+    pub.y = Enc.bufToUrlBase64(pub.y);
+  } else {
+    pub = req.children[2].children[1].children[0];
+    pub = { kty: kty, n: pub.children[0].value, e: pub.children[1].value };
+    while (0 === pub.n[0]) { pub.n = pub.n.slice(1); }
+    while (0 === pub.e[0]) { pub.e = pub.e.slice(1); }
+    pub.n = Enc.bufToUrlBase64(pub.n);
+    pub.e = Enc.bufToUrlBase64(pub.e);
+  }
+  // 4 extensions
+  var domains = req.children[3].children.filter(function (seq) {
+    //  1.2.840.113549.1.9.14 extensionRequest (PKCS #9 via CRMF)
+    if ('2a864886f70d01090e' === Enc.bufToHex(seq.children[0].value)) {
+      return true;
+    }
+  }).map(function (seq) {
+    return seq.children[1].children[0].children.filter(function (seq2) {
+      // subjectAltName (X.509 extension)
+      if ('551d11' === Enc.bufToHex(seq2.children[0].value)) {
+        return true;
+      }
+    }).map(function (seq2) {
+      return seq2.children[1].children[0].children.map(function (name) {
+        // TODO utf8
+        return Enc.bufToBin(name.value);
+      });
+    });
+  })[0];
+
+  return {
+    subject: sub
+  , altnames: domains
+  , jwk: pub
+  , signature: sig
+  };
+};
+
 X509.packCsrRsaPublicKey = function (jwk) {
   // Sequence the key
   var n = ASN1.UInt(Enc.base64ToHex(jwk.n));
@@ -193,4 +287,12 @@ X509._oids = {
 //, 'P-521': '2B 81 04 00 23'
 };
 
+// don't replace the full parseBlock, if it exists
+PEM.parseBlock = PEM.parseBlock || function (str) {
+  var der = str.split(/\n/).filter(function (line) {
+    return !/-----/.test(line);
+  }).join('');
+  return { bytes: Enc.base64ToBuf(der) };
+};
+
 }('undefined' === typeof window ? module.exports : window));