diff --git a/browser.js b/browser.js
new file mode 100644
index 0000000..3b08495
--- /dev/null
+++ b/browser.js
@@ -0,0 +1,134 @@
+;(function (exports) {
+'use strict';
+
+var PromiseA;
+try {
+  /*global Promise*/
+  PromiseA = Promise;
+} catch(e) {
+  PromiseA = require('bluebird');
+}
+
+
+// https://stackoverflow.com/questions/40314257/export-webcrypto-key-to-pem-format
+function derToPem(keydata, pemName, privacy){
+  var keydataS = arrayBufferToString(keydata);
+  var keydataB64 = window.btoa(keydataS);
+  var keydataB64Pem = formatAsPem(keydataB64, pemName, privacy);
+  return keydataB64Pem;
+}
+
+function arrayBufferToString( buffer ) {
+  var binary = [];
+  var bytes = new Uint8Array( buffer );
+  var len = bytes.byteLength;
+  for (var i = 0; i < len; i++) {
+      binary.push(String.fromCharCode( bytes[ i ] ));
+  }
+  return binary.join('');
+}
+
+
+function formatAsPem(str, pemName, privacy) {
+  var privstr = (privacy ? privacy + ' ' : '');
+  var finalString = '-----BEGIN ' + pemName + ' ' + privstr + 'KEY-----\n';
+
+  while (str.length > 0) {
+      finalString += str.substring(0, 64) + '\n';
+      str = str.substring(64);
+  }
+
+  finalString = finalString + '-----END ' + pemName + ' ' + privstr + 'KEY-----';
+
+  return finalString;
+}
+
+var Keypairs = exports.Keypairs = {
+  generate: function(opts) {
+    if (!opts) { opts = {}; }
+    if (!opts.type) { opts.type = 'EC'; }
+
+    var supported = [ 'EC', 'RSA' ];
+    if (-1 === supported.indexOf(opts.type)) {
+      return PromiseA.reject(new Error("'" + opts.type + "' not implemented. Try one of " + supported.join(', ')));
+    }
+
+    if ('EC' === opts.type) {
+      return Keypairs._generateEc(opts);
+    }
+    if ('RSA' === opts.type) {
+      return Keypairs._generateRsa(opts);
+    }
+  }
+, _generateEc: function (opts) {
+    if (!opts.namedCurve) { opts.namedCurve = 'P-256'; }
+    if ('P-256' !== opts.namedCurve) {
+      console.warn("'" + opts.namedCurve + "' is not supported, but it _might_ happen to work anyway.");
+    }
+
+    // https://github.com/diafygi/webcrypto-examples#ecdsa---generatekey
+    var extractable = true;
+
+    return window.crypto.subtle.generateKey(
+      { name: "ECDSA", namedCurve: opts.namedCurve }
+    , extractable
+    , [ 'sign', 'verify' ]
+    ).then(function (result) {
+      return window.crypto.subtle.exportKey(
+        "jwk"
+      , result.privateKey
+      ).then(function (jwk) {
+        return window.crypto.subtle.exportKey(
+          "pkcs8"
+        , result.privateKey
+        ).then(function (keydata) {
+          return {
+            type: 'EC'
+          , privateJwk: jwk
+          , privatePem: derToPem(keydata, 'EC', 'PRIVATE')
+          };
+        });
+      });
+    });
+  }
+, _generateRsa: function (opts) {
+    if (!opts.bitlength) { opts.bitlength = 2048; }
+    if (-1 === [ 2048, 4096 ].indexOf(opts.bitlength)) {
+      return PromiseA.reject("opts.bitlength = (" + typeof opts.bitlength + ") " + opts.bitlength + ": Are you serious?");
+    }
+
+    // https://github.com/diafygi/webcrypto-examples#rsa---generatekey
+    var extractable = true;
+
+    return window.crypto.subtle.generateKey(
+      { name: "RSASSA-PKCS1-v1_5"
+      , modulusLength: opts.bitlength
+      , publicExponent: new Uint8Array([0x01, 0x00, 0x01])
+      , hash: { name: "SHA-256" }
+      }
+    , extractable
+    , [ 'sign', 'verify' ]
+    ).then(function (result) {
+      return window.crypto.subtle.exportKey(
+        "jwk"
+      , result.privateKey
+      ).then(function (jwk) {
+        return window.crypto.subtle.exportKey(
+          "pkcs8"
+        , result.privateKey
+        ).then(function (keydata) {
+          return {
+            type: 'RSA'
+          , privateJwk: jwk
+          , privatePem: derToPem(keydata, 'RSA', 'PRIVATE')
+          };
+        });
+      });
+    });
+  }
+};
+
+}('undefined' === typeof module ? window : module.exports));
+
+// How we might use this
+// var Keypairs = require('keypairs').Keypairs
diff --git a/index.js b/index.js
index 3b08495..320ee40 100644
--- a/index.js
+++ b/index.js
@@ -1,134 +1,3 @@
-;(function (exports) {
 'use strict';
 
-var PromiseA;
-try {
-  /*global Promise*/
-  PromiseA = Promise;
-} catch(e) {
-  PromiseA = require('bluebird');
-}
-
-
-// https://stackoverflow.com/questions/40314257/export-webcrypto-key-to-pem-format
-function derToPem(keydata, pemName, privacy){
-  var keydataS = arrayBufferToString(keydata);
-  var keydataB64 = window.btoa(keydataS);
-  var keydataB64Pem = formatAsPem(keydataB64, pemName, privacy);
-  return keydataB64Pem;
-}
-
-function arrayBufferToString( buffer ) {
-  var binary = [];
-  var bytes = new Uint8Array( buffer );
-  var len = bytes.byteLength;
-  for (var i = 0; i < len; i++) {
-      binary.push(String.fromCharCode( bytes[ i ] ));
-  }
-  return binary.join('');
-}
-
-
-function formatAsPem(str, pemName, privacy) {
-  var privstr = (privacy ? privacy + ' ' : '');
-  var finalString = '-----BEGIN ' + pemName + ' ' + privstr + 'KEY-----\n';
-
-  while (str.length > 0) {
-      finalString += str.substring(0, 64) + '\n';
-      str = str.substring(64);
-  }
-
-  finalString = finalString + '-----END ' + pemName + ' ' + privstr + 'KEY-----';
-
-  return finalString;
-}
-
-var Keypairs = exports.Keypairs = {
-  generate: function(opts) {
-    if (!opts) { opts = {}; }
-    if (!opts.type) { opts.type = 'EC'; }
-
-    var supported = [ 'EC', 'RSA' ];
-    if (-1 === supported.indexOf(opts.type)) {
-      return PromiseA.reject(new Error("'" + opts.type + "' not implemented. Try one of " + supported.join(', ')));
-    }
-
-    if ('EC' === opts.type) {
-      return Keypairs._generateEc(opts);
-    }
-    if ('RSA' === opts.type) {
-      return Keypairs._generateRsa(opts);
-    }
-  }
-, _generateEc: function (opts) {
-    if (!opts.namedCurve) { opts.namedCurve = 'P-256'; }
-    if ('P-256' !== opts.namedCurve) {
-      console.warn("'" + opts.namedCurve + "' is not supported, but it _might_ happen to work anyway.");
-    }
-
-    // https://github.com/diafygi/webcrypto-examples#ecdsa---generatekey
-    var extractable = true;
-
-    return window.crypto.subtle.generateKey(
-      { name: "ECDSA", namedCurve: opts.namedCurve }
-    , extractable
-    , [ 'sign', 'verify' ]
-    ).then(function (result) {
-      return window.crypto.subtle.exportKey(
-        "jwk"
-      , result.privateKey
-      ).then(function (jwk) {
-        return window.crypto.subtle.exportKey(
-          "pkcs8"
-        , result.privateKey
-        ).then(function (keydata) {
-          return {
-            type: 'EC'
-          , privateJwk: jwk
-          , privatePem: derToPem(keydata, 'EC', 'PRIVATE')
-          };
-        });
-      });
-    });
-  }
-, _generateRsa: function (opts) {
-    if (!opts.bitlength) { opts.bitlength = 2048; }
-    if (-1 === [ 2048, 4096 ].indexOf(opts.bitlength)) {
-      return PromiseA.reject("opts.bitlength = (" + typeof opts.bitlength + ") " + opts.bitlength + ": Are you serious?");
-    }
-
-    // https://github.com/diafygi/webcrypto-examples#rsa---generatekey
-    var extractable = true;
-
-    return window.crypto.subtle.generateKey(
-      { name: "RSASSA-PKCS1-v1_5"
-      , modulusLength: opts.bitlength
-      , publicExponent: new Uint8Array([0x01, 0x00, 0x01])
-      , hash: { name: "SHA-256" }
-      }
-    , extractable
-    , [ 'sign', 'verify' ]
-    ).then(function (result) {
-      return window.crypto.subtle.exportKey(
-        "jwk"
-      , result.privateKey
-      ).then(function (jwk) {
-        return window.crypto.subtle.exportKey(
-          "pkcs8"
-        , result.privateKey
-        ).then(function (keydata) {
-          return {
-            type: 'RSA'
-          , privateJwk: jwk
-          , privatePem: derToPem(keydata, 'RSA', 'PRIVATE')
-          };
-        });
-      });
-    });
-  }
-};
-
-}('undefined' === typeof module ? window : module.exports));
-
-// How we might use this
-// var Keypairs = require('keypairs').Keypairs
+module.exports = require('./lib/keypairs.js');
diff --git a/lib/ec.js b/lib/ec.js
new file mode 100644
index 0000000..e4434dc
--- /dev/null
+++ b/lib/ec.js
@@ -0,0 +1,62 @@
+'use strict';
+
+var ASN1 = require('./asn1-packer.js');
+var Enc = require('./encoding.js');
+var x509 = module.exports;
+
+// 1.2.840.10045.3.1.7
+// prime256v1 (ANSI X9.62 named elliptic curve)
+var OBJ_ID_EC  = '06 08 2A8648CE3D030107'.replace(/\s+/g, '').toLowerCase();
+// 1.3.132.0.34
+// secp384r1 (SECG (Certicom) named elliptic curve)
+var OBJ_ID_EC_384 = '06 05 2B81040022'.replace(/\s+/g, '').toLowerCase();
+// 1.2.840.10045.2.1
+// ecPublicKey (ANSI X9.62 public key type)
+var OBJ_ID_EC_PUB = '06 07 2A8648CE3D0201'.replace(/\s+/g, '').toLowerCase();
+
+x509.packSec1 = function (jwk) {
+  var d = Enc.base64ToHex(jwk.d);
+  var x = Enc.base64ToHex(jwk.x);
+  var y = Enc.base64ToHex(jwk.y);
+  var objId = ('P-256' === jwk.crv) ? OBJ_ID_EC : OBJ_ID_EC_384;
+  return Enc.hexToUint8(
+    ASN1('30'
+    , ASN1.UInt('01')
+    , ASN1('04', d)
+    , ASN1('A0', objId)
+    , ASN1('A1', ASN1.BitStr('04' + x + y)))
+  );
+};
+x509.packPkcs8 = function (jwk) {
+  var d = Enc.base64ToHex(jwk.d);
+  var x = Enc.base64ToHex(jwk.x);
+  var y = Enc.base64ToHex(jwk.y);
+  var objId = ('P-256' === jwk.crv) ? OBJ_ID_EC : OBJ_ID_EC_384;
+  return Enc.hexToUint8(
+    ASN1('30'
+    , ASN1.UInt('00')
+    , ASN1('30'
+      , OBJ_ID_EC_PUB
+      , objId
+      )
+    , ASN1('04'
+      , ASN1('30'
+        , ASN1.UInt('01')
+        , ASN1('04', d)
+        , ASN1('A1', ASN1.BitStr('04' + x + y)))))
+  );
+};
+x509.packSpki = function (jwk) {
+  var x = Enc.base64ToHex(jwk.x);
+  var y = Enc.base64ToHex(jwk.y);
+  var objId = ('P-256' === jwk.crv) ? OBJ_ID_EC : OBJ_ID_EC_384;
+  return Enc.hexToUint8(
+    ASN1('30'
+    , ASN1('30'
+      , OBJ_ID_EC_PUB
+      , objId
+      )
+    , ASN1.BitStr('04' + x + y))
+  );
+};
+x509.packPkix = x509.packSpki;
diff --git a/lib/keypairs.js b/lib/keypairs.js
new file mode 100644
index 0000000..e4fc43b
--- /dev/null
+++ b/lib/keypairs.js
@@ -0,0 +1,104 @@
+'use strict';
+
+/*global Promise*/
+var keypairs = module.exports;
+
+var PEM = require('./pem-parser.js');
+PEM.packBlock = require('./pem-packer.js').packBlock;
+
+var ASN1 = require('./asn1-parser.js');
+ASN1.pack = require('./asn1-packer.js').pack;
+
+var x509 = require('./x509-parser.js');
+
+var SSH = require('./ssh-parser.js');
+SSH.pack = require('./ssh-packer.js').pack;
+
+// sign, signJws, signJwt
+var JWS = require('./jws.js');
+var JWT = require('./jwt.js');
+
+var RSA = require('./rsa.js');
+var EC = require('./ec.js');
+
+keypairs.import = function (opts) {
+  return Promise.resolve().then(function () {
+    var jwk = opts.jwk;
+    var pem;
+    var der;
+    var typ;
+
+    if (opts.pem) {
+      pem = PEM.parseBlock(opts.pem);
+      if (/OPENSSH/.test(pem.type)) {
+        jwk = SSH.parse(pem);
+      } else {
+        der = pem.bytes;
+        jwk = x509.parse(der);
+      }
+    }
+    if (opts.ssh) {
+      jwk = SSH.parse(opts.ssh);
+    }
+    if (jwk) {
+      // Both RSA and EC use 'd' as part of the private key
+      if (jwk.d) {
+        typ = 'PRIVATE KEY';
+        der = x509.pack({ jwk: jwk, format: 'pkcs8', encoding: 'pem' });
+      } else {
+        typ = 'PUBLIC KEY';
+        der = x509.pack({ jwk: jwk, format: 'spki', encoding: 'pem' });
+      }
+      pem = PEM.packBlock({ type: typ, bytes: der });
+    }
+
+    return { pem: pem, jwk: jwk };
+  });
+};
+
+keypairs.export = function (opts) {
+  // { pem, jwk, format, encoding }
+  var format = opts.format;
+  var encoding = opts.encoding;
+  var jwk = opts.jwk;
+  var pem = opts.pem;
+  var der = opts.der;
+  var pub = opts.public;
+
+  if (opts.key) {
+    if ('string' === typeof opts.key) {
+      pem = opts.key;
+    } else if (opts.key.d) {
+      jwk = opts.key;
+    } else if (opts.key.length) {
+      der = opts.der;
+    } else {
+      throw new Error("'key' must be of type 'string' (PEM), 'object' (JWK), Buffer, or Array (DER)");
+    }
+  }
+  if (!format) { format = 'jwk'; }
+
+  if (!jwk) {
+    jwk = keypairs.import({ pem: pem }).jwk;
+  }
+  if (pub) {
+    if ('RSA' === jwk.kty) {
+      jwk = { kty: jwk.kty, n: jwk.n, e: jwk.e };
+    } else {
+      jwk = { kty: jwk.kty, x: jwk.x, y: jwk.y };
+    }
+  }
+  if ('jwk' === format) {
+    if (encoding && 'json' !== encoding) {
+      throw new Error("'encoding' must be 'json' for 'jwk'");
+    }
+    return jwk;
+  }
+
+  if ('openssh' === format || 'ssh' === format) {
+    // TODO if ('ssh' === format) { format = 'pkcs8'; }
+    // TODO 'ssh2' public key is a special variant of pkcs8
+    return SSH.pack({ jwk: jwk, public: opts.public });
+  }
+  return x509.pack({ jwk: jwk, format: opts.format, encoding: opts.encoding, public: opts.public });
+};
diff --git a/lib/x509-packer.js b/lib/x509-packer.js
new file mode 100644
index 0000000..914b3e8
--- /dev/null
+++ b/lib/x509-packer.js
@@ -0,0 +1,14 @@
+'use strict';
+
+var x509 = module.exports;
+
+var RSA = require('./rsa.js');
+var EC = require('./ec.js');
+
+x509.pack = function (opts) {
+  if ('RSA' === opts.jwk.kty) {
+    return RSA.pack(opts);
+  } else {
+    return EC.pack(opts);
+  }
+};
diff --git a/lib/x509-parser.js b/lib/x509-parser.js
new file mode 100644
index 0000000..870d5ba
--- /dev/null
+++ b/lib/x509-parser.js
@@ -0,0 +1,119 @@
+'use strict';
+
+var Enc = require('./encoding.js');
+var x509 = module.exports;
+
+// 1.2.840.10045.3.1.7
+// prime256v1 (ANSI X9.62 named elliptic curve)
+var OBJ_ID_EC  = '06 08 2A8648CE3D030107'.replace(/\s+/g, '').toLowerCase();
+// 1.3.132.0.34
+// secp384r1 (SECG (Certicom) named elliptic curve)
+var OBJ_ID_EC_384 = '06 05 2B81040022'.replace(/\s+/g, '').toLowerCase();
+
+x509.parseSec1 = function parseEcOnlyPrivkey(u8, jwk) {
+  var index = 7;
+  var len = 32;
+  var olen = OBJ_ID_EC.length/2;
+
+  if ("P-384" === jwk.crv) {
+    olen = OBJ_ID_EC_384.length/2;
+    index = 8;
+    len = 48;
+  }
+  if (len !== u8[index - 1]) {
+    throw new Error("Unexpected bitlength " + len);
+  }
+
+  // private part is d
+  var d = u8.slice(index, index + len);
+  // compression bit index
+  var ci = index + len + 2 + olen + 2 + 3;
+  var c = u8[ci];
+  var x, y;
+
+  if (0x04 === c) {
+    y = u8.slice(ci + 1 + len, ci + 1 + len + len);
+  } else if (0x02 !== c) {
+    throw new Error("not a supported EC private key");
+  }
+  x = u8.slice(ci + 1, ci + 1 + len);
+
+  return {
+    kty: jwk.kty
+  , crv: jwk.crv
+  , d: Enc.bufToUrlBase64(d)
+  //, dh: Enc.bufToHex(d)
+  , x: Enc.bufToUrlBase64(x)
+  //, xh: Enc.bufToHex(x)
+  , y: Enc.bufToUrlBase64(y)
+  //, yh: Enc.bufToHex(y)
+  };
+};
+
+x509.parsePkcs8 = function parseEcPkcs8(u8, jwk) {
+  var index = 24 + (OBJ_ID_EC.length/2);
+  var len = 32;
+  if ("P-384" === jwk.crv) {
+    index = 24 + (OBJ_ID_EC_384.length/2) + 2;
+    len = 48;
+  }
+
+  //console.log(index, u8.slice(index));
+  if (0x04 !== u8[index]) {
+    //console.log(jwk);
+    throw new Error("privkey not found");
+  }
+  var d = u8.slice(index+2, index+2+len);
+  var ci = index+2+len+5;
+  var xi = ci+1;
+  var x = u8.slice(xi, xi + len);
+  var yi = xi+len;
+  var y;
+  if (0x04 === u8[ci]) {
+    y = u8.slice(yi, yi + len);
+  } else if (0x02 !== u8[ci]) {
+    throw new Error("invalid compression bit (expected 0x04 or 0x02)");
+  }
+
+  return {
+    kty: jwk.kty
+  , crv: jwk.crv
+  , d: Enc.bufToUrlBase64(d)
+  //, dh: Enc.bufToHex(d)
+  , x: Enc.bufToUrlBase64(x)
+  //, xh: Enc.bufToHex(x)
+  , y: Enc.bufToUrlBase64(y)
+  //, yh: Enc.bufToHex(y)
+  };
+};
+
+x509.parseSpki = function parsePem(u8, jwk) {
+  var ci = 16 + OBJ_ID_EC.length/2;
+  var len = 32;
+
+  if ("P-384" === jwk.crv) {
+    ci = 16 + OBJ_ID_EC_384.length/2;
+    len = 48;
+  }
+
+  var c = u8[ci];
+  var xi = ci + 1;
+  var x = u8.slice(xi, xi + len);
+  var yi = xi + len;
+  var y;
+  if (0x04 === c) {
+    y = u8.slice(yi, yi + len);
+  } else if (0x02 !== c) {
+    throw new Error("not a supported EC private key");
+  }
+
+  return {
+    kty: jwk.kty
+  , crv: jwk.crv
+  , x: Enc.bufToUrlBase64(x)
+  //, xh: Enc.bufToHex(x)
+  , y: Enc.bufToUrlBase64(y)
+  //, yh: Enc.bufToHex(y)
+  };
+};
+x509.parsePkix = x509.parseSpki;