diff --git a/README.md b/README.md
index 2840fb7..9d4d580 100644
--- a/README.md
+++ b/README.md
@@ -11,13 +11,17 @@ Features
 < 75 lines of code | < 0.7kb gzipped | 1.5kb minified | 2.1kb with comments
 
 * [x] SSH Public Keys
-* [x] RSA Public Keys
-* [x] EC Public Keys
+* [x] OpenSSH Private Keys
+* [x] RSA Keys
+* [x] EC Keys
   * P-256 (prime256v1, secp256r1)
   * P-384 (secp384r1)
 * [x] Browser Version
   * [Bluecrypt JWK to SSH](https://git.coolaj86.com/coolaj86/bluecrypt-jwk-to-ssh.js)
 
+Note: the file size stats are for v1.0 which did not include private key packing.
+I plan to go back and update the stats, but just know that it grew a little over 2x.
+
 ### Need JWK to SSH? PEM to SSH?
 
 Try one of these:
@@ -26,12 +30,35 @@ Try one of these:
 * [Eckles.js](https://git.coolaj86.com/coolaj86/eckles.js) (more EC utils)
 * [Rasha.js](https://git.coolaj86.com/coolaj86/eckles.js) (more RSA utils)
 
-### Need SSH Private Keys?
+### Need Alternate SSH Private Keys?
 
-SSH private keys are just normal PEM files,
-so you can use Eckles or Rasha, as mentioned above.
+This library supports OpenSSH private keys.
 
-# CLI
+  * [x] OpenSSH
+  * [ ] Normal PKCS1 / SEC1 / PKCS8
+    * [x] Rasha.js
+    * [x] Eckles.js
+  * [ ] Putty
+
+# Library Usage
+
+You can also use it from JavaScript:
+
+```js
+var fs = require('fs');
+var jwktossh = require('jwk-to-ssh');
+
+var jwk = JSON.parse(fs.readFileSync("./privkey.jwk.json"));
+var pub = jwktossh.pack({
+  jwk: jwk
+, comment: 'root@localhost'
+, public: true
+});
+
+console.info(pub);
+```
+
+# CLI Usage
 
 You can install `jwk-to-ssh` and use it from command line:
 
@@ -39,25 +66,20 @@ You can install `jwk-to-ssh` and use it from command line:
 npm install -g jwk-to-ssh
 ```
 
+```bash
+jwk-to-ssh [keyfile] [comment] [public]
+```
+
 ```bash
 jwk-to-ssh pubkey.jwk.json
 ```
 
-# Usage
+```bash
+jwk-to-ssh privkey.jwk.json root@localhost
+```
 
-You can also use it from JavaScript:
-
-```js
-var fs = require('fs');
-var jwktossh = require('jwk-to-ssh');
-
-var jwk = JSON.parse(fs.readFileSync("./pubkey.jwk.json"));
-var pub = jwktossh.pack({
-  jwk: jwk
-, comment: 'root@localhost'
-});
-
-console.info(pub);
+```bash
+jwk-to-ssh privkey.jwk.json root@localhost public
 ```
 
 Legal
diff --git a/bin/jwk-to-ssh.js b/bin/jwk-to-ssh.js
index 9493044..c4ea6fa 100755
--- a/bin/jwk-to-ssh.js
+++ b/bin/jwk-to-ssh.js
@@ -5,6 +5,8 @@ var path = require('path');
 var jwktossh = require('../index.js');
 
 var pubfile = process.argv[2];
+var comment = process.argv[3] || 'root@localhost';
+var pub = ('public' === process.argv[4]);
 
 if (!pubfile) {
   console.error("specify a path to JWK");
@@ -12,7 +14,6 @@ if (!pubfile) {
 }
 
 var jwk = require(path.join(process.cwd(), pubfile));
-var comment = process.argv[3] || 'root@localhost';
-var pub = jwktossh.pack({ jwk: jwk, comment: comment });
+var out = jwktossh.pack({ jwk: jwk, comment: comment, public: pub });
 
-console.info(pub);
+console.info(out);
diff --git a/fixtures/privkey-ec-p256.jwk.json b/fixtures/privkey-ec-p256.jwk.json
new file mode 100644
index 0000000..2e9455d
--- /dev/null
+++ b/fixtures/privkey-ec-p256.jwk.json
@@ -0,0 +1,7 @@
+{
+  "kty": "EC",
+  "crv": "P-256",
+  "d": "iYydo27aNGO9DBUWeGEPD8oNi1LZDqfxPmQlieLBjVQ",
+  "x": "IT1SWLxsacPiE5Z16jkopAn8_-85rMjgyCokrnjDft4",
+  "y": "mP2JwOAOdMmXuwpxbKng3KZz27mz-nKWIlXJ3rzSGMo"
+}
diff --git a/fixtures/privkey-ec-p256.openssh.pem b/fixtures/privkey-ec-p256.openssh.pem
new file mode 100644
index 0000000..25720bf
--- /dev/null
+++ b/fixtures/privkey-ec-p256.openssh.pem
@@ -0,0 +1,9 @@
+-----BEGIN OPENSSH PRIVATE KEY-----
+b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAaAAAABNlY2RzYS
+1zaGEyLW5pc3RwMjU2AAAACG5pc3RwMjU2AAAAQQQhPVJYvGxpw+ITlnXqOSikCfz/7zms
+yODIKiSueMN+3pj9icDgDnTJl7sKcWyp4Nymc9u5s/pyliJVyd680hjKAAAAqGJjanNiY2
+pzAAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBCE9Uli8bGnD4hOW
+deo5KKQJ/P/vOazI4MgqJK54w37emP2JwOAOdMmXuwpxbKng3KZz27mz+nKWIlXJ3rzSGM
+oAAAAhAImMnaNu2jRjvQwVFnhhDw/KDYtS2Q6n8T5kJYniwY1UAAAADnJvb3RAbG9jYWxo
+b3N0AQ==
+-----END OPENSSH PRIVATE KEY-----
diff --git a/fixtures/privkey-ec-p384.jwk.json b/fixtures/privkey-ec-p384.jwk.json
new file mode 100644
index 0000000..7bb65f8
--- /dev/null
+++ b/fixtures/privkey-ec-p384.jwk.json
@@ -0,0 +1,7 @@
+{
+  "kty": "EC",
+  "crv": "P-384",
+  "d": "XlyuCEWSTTS8U79O_Mz05z18vh4kb10szvu_7pdXuGWV6lfEyPExyUYWsA6A2kdV",
+  "x": "2zEU0bKCa7ejKLIJ8oPGnLhqhxyiv4_w38K2a0SPC6dsSd9_glNJ8lcqv0sff5Gb",
+  "y": "VD4jnu83S6scn6_TeAj3EZOREGbOs6dzoVpaugn-XQMMyC9O4VLbDDFGBZTJlMsb"
+}
diff --git a/fixtures/privkey-ec-p384.openssh.pem b/fixtures/privkey-ec-p384.openssh.pem
new file mode 100644
index 0000000..5e7ad93
--- /dev/null
+++ b/fixtures/privkey-ec-p384.openssh.pem
@@ -0,0 +1,10 @@
+-----BEGIN OPENSSH PRIVATE KEY-----
+b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAiAAAABNlY2RzYS
+1zaGEyLW5pc3RwMzg0AAAACG5pc3RwMzg0AAAAYQTbMRTRsoJrt6Mosgnyg8acuGqHHKK/
+j/DfwrZrRI8Lp2xJ33+CU0nyVyq/Sx9/kZtUPiOe7zdLqxyfr9N4CPcRk5EQZs6zp3OhWl
+q6Cf5dAwzIL07hUtsMMUYFlMmUyxsAAADYYmNqc2JjanMAAAATZWNkc2Etc2hhMi1uaXN0
+cDM4NAAAAAhuaXN0cDM4NAAAAGEE2zEU0bKCa7ejKLIJ8oPGnLhqhxyiv4/w38K2a0SPC6
+dsSd9/glNJ8lcqv0sff5GbVD4jnu83S6scn6/TeAj3EZOREGbOs6dzoVpaugn+XQMMyC9O
+4VLbDDFGBZTJlMsbAAAAMF5crghFkk00vFO/TvzM9Oc9fL4eJG9dLM77v+6XV7hllepXxM
+jxMclGFrAOgNpHVQAAAA5yb290QGxvY2FsaG9zdAEC
+-----END OPENSSH PRIVATE KEY-----
diff --git a/fixtures/privkey-rsa-2048.jwk.json b/fixtures/privkey-rsa-2048.jwk.json
new file mode 100644
index 0000000..130d540
--- /dev/null
+++ b/fixtures/privkey-rsa-2048.jwk.json
@@ -0,0 +1,9 @@
+{
+  "kty": "RSA",
+  "n": "m2ttVBxPlWw06ZmGBWVDlfjkPAJ4DgnY0TrDwtCohHzLxGhDNzUJefLukC-xu0LBKylYojT5vTkxaOhxeSYo31syu4WhxbkTBLICOFcCGMob6pSQ38P8LdAIlb0pqDHxEJ9adWomjuFf0SUhN1cP7s9m8Yk9trkpEqjskocn2BOnTB57qAZM6-I70on0_iDZm7-jcqOPgADAmbWHhy67BXkk4yy_YzD4yOGZFXZcNp915_TW5bRd__AKPHUHxJasPiyEFqlNKBR2DSD-LbX5eTmzCh2ikrwTMja7mUdBJf2bK3By5AB0Qi49OykUCfNZeQlEz7UNNj9RGps_50-CNw",
+  "e": "AQAB",
+  "d": "Cpfo7Mm9Nu8YMC_xrZ54W9mKHPkCG9rZ93Ds9PNp-RXUgb-ljTbFPZWsYxGNKLllFz8LNosr1pT2ZDMrwNk0Af1iWNvD6gkyXaiQdCyiDPSBsJyNv2LJZon-e85X74nv53UlIkmo9SYxdLz2JaJ-iIWEe8Qh-7llLktrTJV_xr98_tbhgSppz_IeOymq3SEZaQHM8pTU7w7XvCj2pb9r8fN0M0XcgWZIaf3LGEfkhF_WtX67XJ0C6-LbkT51jtlLRNGX6haGdscXS0OWWjKOJzKGuV-NbthEn5rmRtVnjRZ3yaxQ0ud8vC-NONn7yvGUlOur1IdDzJ_YfHPt9sHMQQ",
+  "p": "ynG-t9HwKCN3MWRYFdnFzi9-02Qcy3p8B5pu3ary2E70hYn2pHlUG2a9BNE8c5xHQ3Hx43WoWf6s0zOunPV1G28LkU_UYEbAtPv_PxSmzpQp9n9XnYvBLBF8Y3z7gxgLn1vVFNARrQdRtj87qY3aw7E9S4DsGcAarIuOT2TsTCE",
+  "q": "xIkAjgUzB1zaUzJtW2Zgvp9cYYr1DmpH30ePZl3c_8397_DZDDo46fnFYjs6uPa03HpmKUnbjwr14QHlfXlntJBEuXxcqLjkdKdJ4ob7xueLTK4suo9V8LSrkLChVxlZQwnFD2E5ll0sVeeDeMJHQw38ahSrBFEVnxjpnPh1Q1c",
+  "qi": "AlHWbx1gp6Z9pbw_1hlS7HuXAgWoX7IjbTUelldf4gkriDWLOrj3QCZcO4ZvZvEwJhVlsny9LO8IkbwGJEL6cXraK08ByVS2mwQyflgTgGNnpzixyEUL_mrQLx6y145FHcxfeqNInMhep-0Mxn1D5nlhmIOgRApS0t9VoXtHhFU"
+}
diff --git a/fixtures/privkey-rsa-2048.openssh.pem b/fixtures/privkey-rsa-2048.openssh.pem
new file mode 100644
index 0000000..ca14bc9
--- /dev/null
+++ b/fixtures/privkey-rsa-2048.openssh.pem
@@ -0,0 +1,27 @@
+-----BEGIN OPENSSH PRIVATE KEY-----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+-----END OPENSSH PRIVATE KEY-----
diff --git a/fixtures/pub-ec-p256.ssh.pub b/fixtures/pub-ec-p256.ssh.pub
new file mode 100644
index 0000000..5b6b77b
--- /dev/null
+++ b/fixtures/pub-ec-p256.ssh.pub
@@ -0,0 +1 @@
+ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBCE9Uli8bGnD4hOWdeo5KKQJ/P/vOazI4MgqJK54w37emP2JwOAOdMmXuwpxbKng3KZz27mz+nKWIlXJ3rzSGMo= root@localhost
diff --git a/fixtures/pub-ec-p384.ssh.pub b/fixtures/pub-ec-p384.ssh.pub
new file mode 100644
index 0000000..552074d
--- /dev/null
+++ b/fixtures/pub-ec-p384.ssh.pub
@@ -0,0 +1 @@
+ecdsa-sha2-nistp384 AAAAE2VjZHNhLXNoYTItbmlzdHAzODQAAAAIbmlzdHAzODQAAABhBNsxFNGygmu3oyiyCfKDxpy4aoccor+P8N/CtmtEjwunbEnff4JTSfJXKr9LH3+Rm1Q+I57vN0urHJ+v03gI9xGTkRBmzrOnc6FaWroJ/l0DDMgvTuFS2wwxRgWUyZTLGw== root@localhost
diff --git a/fixtures/pub-rsa-2048.ssh.pub b/fixtures/pub-rsa-2048.ssh.pub
new file mode 100644
index 0000000..97429c2
--- /dev/null
+++ b/fixtures/pub-rsa-2048.ssh.pub
@@ -0,0 +1 @@
+ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCba21UHE+VbDTpmYYFZUOV+OQ8AngOCdjROsPC0KiEfMvEaEM3NQl58u6QL7G7QsErKViiNPm9OTFo6HF5JijfWzK7haHFuRMEsgI4VwIYyhvqlJDfw/wt0AiVvSmoMfEQn1p1aiaO4V/RJSE3Vw/uz2bxiT22uSkSqOyShyfYE6dMHnuoBkzr4jvSifT+INmbv6Nyo4+AAMCZtYeHLrsFeSTjLL9jMPjI4ZkVdlw2n3Xn9NbltF3/8Ao8dQfElqw+LIQWqU0oFHYNIP4ttfl5ObMKHaKSvBMyNruZR0El/ZsrcHLkAHRCLj07KRQJ81l5CUTPtQ02P1Eamz/nT4I3 root@localhost
diff --git a/lib/encoding.js b/lib/encoding.js
index a369e6c..8bc0d0d 100644
--- a/lib/encoding.js
+++ b/lib/encoding.js
@@ -6,6 +6,14 @@ Enc.base64ToHex = function (b64) {
   return Buffer.from(b64, 'base64').toString('hex');
 };
 
+Enc.binToBuf = function (bin) {
+  return Buffer.from(bin, 'binary');
+};
+
+Enc.bufToBase64 = function (u8) {
+  return Buffer.from(u8).toString('base64');
+};
+
 Enc.binToHex = function (bin) {
   return Buffer.from(bin, 'binary').toString('hex');
 };
@@ -13,3 +21,7 @@ Enc.binToHex = function (bin) {
 Enc.hexToBase64 = function (hex) {
   return Buffer.from(hex, 'hex').toString('base64');
 };
+
+Enc.hexToBin = function (hex) {
+  return Buffer.from(hex, 'hex').toString('binary');
+};
diff --git a/lib/pem.js b/lib/pem.js
new file mode 100644
index 0000000..468362b
--- /dev/null
+++ b/lib/pem.js
@@ -0,0 +1,11 @@
+'use strict';
+
+var PEM = module.exports;
+var Enc = require('./encoding.js');
+
+PEM.packBlock = function (opts) {
+  return '-----BEGIN ' + opts.type + '-----\n'
+    + Enc.bufToBase64(opts.bytes).match(/.{1,70}/g).join('\n') + '\n'
+    + '-----END ' + opts.type + '-----'
+  ;
+};
diff --git a/lib/ssh-packer.js b/lib/ssh-packer.js
index d6470b0..5c4d7c3 100644
--- a/lib/ssh-packer.js
+++ b/lib/ssh-packer.js
@@ -1,34 +1,92 @@
 'use strict';
 
 var Enc = require('./encoding.js');
+var PEM = require('./pem.js');
 var SSH = module.exports;
 
 SSH.pack = function (opts) {
+  if (opts.jwk.d && !opts.public) {
+    return SSH._packPrivate(opts);
+  } else {
+    delete opts.jwk.d;
+    return SSH._packPublic(opts);
+  }
+};
+
+// https://tools.ietf.org/html/rfc4253#section-6.6
+SSH._packPublic = function (opts) {
+  var els = SSH._packKey(opts);
+  var hex = SSH._packElements(els);
+  var typ = Enc.hexToBin(els[0]);
+  var parts = [ typ, Enc.hexToBase64(hex) ];
+  if (opts.comment) { parts.push(opts.comment); }
+  return parts.join(' ');
+};
+
+SSH._packPrivate = function (opts) {
+  var pubjwk = JSON.parse(JSON.stringify(opts.jwk));
+  delete pubjwk.d;
+  var pubels = SSH._packKey({ jwk: pubjwk });
+  var pubhex = SSH._packElements(pubels);
+  var els = SSH._packKey(opts);
+  var hex = SSH._packElements(els);
+  var privlen = hex.length/2;
+  var padlen = (privlen % 8) && (8 - (privlen % 8)) || 0; // blocksize is 8 (no cipher)
+  var bin = "openssh-key-v1" + String.fromCharCode(0)
+    + Enc.hexToBin(
+        SSH._packElements([
+          Enc.binToHex("none")  // ciphername
+        , Enc.binToHex("none")  // kdfname
+        , ""                    // empty kdf
+        ])
+      + SSH._numToUint32Hex(1)  // number of keys (always 1)
+      + SSH._numToUint32Hex(pubhex.length/2)  // pubkey length
+      + pubhex
+      + SSH._numToUint32Hex(8 + privlen + padlen) // privkey length
+      + '62636a7362636a73'            // 64-bit dummy checksum ("bcjs", "bcjs")
+      + hex                           // (only cihpered keys use real checksums)
+      );
+  var pad = '';
+  var i;
+  for (i = 1; i <= padlen; i += 1) {
+    pad += '0' + i;
+  }
+  return PEM.packBlock({
+    type: "OPENSSH PRIVATE KEY"
+  , bytes: Enc.binToBuf(bin + Enc.hexToBin(pad))
+  });
+};
+
+SSH._packKey = function (opts) {
   var jwk = opts.jwk;
   var els = [];
-  var ssh = {
-    type: ''
-  , _elements: els
-  , comment: opts.comment || ''
-  };
   var len;
 
   if ("RSA" === jwk.kty) {
-    ssh.type = 'ssh-rsa';
-    els.push(Enc.binToHex(ssh.type));
-    els.push(SSH._padRsa(Enc.base64ToHex(jwk.e)));
-    els.push(SSH._padRsa(Enc.base64ToHex(jwk.n)));
-    return SSH._packElements(ssh);
+    els.push(Enc.binToHex('ssh-rsa'));
+    if (jwk.d) {
+      // unswap n and e for private key format
+      els.push(SSH._padBigInt(Enc.base64ToHex(jwk.n)));
+      els.push(SSH._padBigInt(Enc.base64ToHex(jwk.e)));
+      els.push(SSH._padBigInt(Enc.base64ToHex(jwk.d)));
+      els.push(SSH._padBigInt(Enc.base64ToHex(jwk.qi)));
+      els.push(SSH._padBigInt(Enc.base64ToHex(jwk.p)));
+      els.push(SSH._padBigInt(Enc.base64ToHex(jwk.q)));
+      els.push(Enc.binToHex(opts.comment || ''));
+    } else {
+      // swap n and e for public key format
+      els.push(SSH._padBigInt(Enc.base64ToHex(jwk.e)));
+      els.push(SSH._padBigInt(Enc.base64ToHex(jwk.n)));
+    }
+    return els;
   }
 
   if ("P-256" === jwk.crv) {
-    ssh.type = 'ecdsa-sha2-nistp256';
-    els.push(Enc.binToHex(ssh.type));
+    els.push(Enc.binToHex('ecdsa-sha2-nistp256'));
     els.push(Enc.binToHex('nistp256'));
     len = 32;
   } else if ("P-384" === jwk.crv) {
-    ssh.type = 'ecdsa-sha2-nistp384';
-    els.push(Enc.binToHex(ssh.type));
+    els.push(Enc.binToHex('ecdsa-sha2-nistp384'));
     els.push(Enc.binToHex('nistp384'));
     len = 48;
   } else {
@@ -36,17 +94,26 @@ SSH.pack = function (opts) {
   }
 
   els.push('04'
-    + SSH._padEc(Enc.base64ToHex(jwk.x), len)
-    + SSH._padEc(Enc.base64ToHex(jwk.y), len)
+    + SSH._padBytes(Enc.base64ToHex(jwk.x), len)
+    + SSH._padBytes(Enc.base64ToHex(jwk.y), len)
   );
-  return SSH._packElements(ssh);
+  if (jwk.d) {
+    // I was able to empirically confirm that the leading 00 is expected for
+    // ambiguous BigInt negatives (0x80 set), and that the length can dip down
+    // to 31 bytes when the leading byte is 0x00. I suspect that if I had tried
+    // 65k iterations that I'd have seen at least one 30 byte number
+    els.push(SSH._padBigInt(Enc.base64ToHex(jwk.d)));
+    //console.warn('els:', els[els.length - 1]);
+    els.push(Enc.binToHex(opts.comment || ''));
+  }
+
+  return els;
 };
 
-SSH._packElements = function (ssh) {
-  var hex = ssh._elements.map(function (hex) {
+SSH._packElements = function(els) {
+  return els.map(function (hex) {
     return SSH._numToUint32Hex(hex.length/2) + hex;
   }).join('');
-  return [ ssh.type, Enc.hexToBase64(hex), ssh.comment ].join(' ');
 };
 
 SSH._numToUint32Hex = function (num) {
@@ -57,18 +124,20 @@ SSH._numToUint32Hex = function (num) {
   return hex;
 };
 
-SSH._padRsa = function (hex) {
+SSH._padBigInt = function (hex) {
   // BigInt is negative if the high order bit 0x80 is set,
   // so ASN1, SSH, and many other formats pad with '0x00'
   // to signifiy a positive number.
   var i = parseInt(hex.slice(0, 2), 16);
+  //console.warn('l', hex.length/2, 'i', i);
   if (0x80 & i) {
+    //console.warn('0x80 true');
     return '00' + hex;
   }
   return hex;
 };
 
-SSH._padEc = function (hex, len) {
+SSH._padBytes = function (hex, len) {
   while (hex.length < len * 2) {
     hex = '00' + hex;
   }
diff --git a/package.json b/package.json
index 9e85bbf..47f001b 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "jwk-to-ssh",
-  "version": "1.0.1",
+  "version": "1.2.0",
   "description": "💯 JWK to SSH in a lightweight, zero-dependency library.",
   "homepage": "https://git.coolaj86.com/coolaj86/jwk-to-ssh.js",
   "main": "index.js",
diff --git a/test.sh b/test.sh
new file mode 100755
index 0000000..e4d1d8f
--- /dev/null
+++ b/test.sh
@@ -0,0 +1,32 @@
+#!/bin/bash
+set -e
+
+chmod 0600 fixtures/*
+
+# creates a new key
+#ssh-keygen -t rsa -b 2048 -C root@localhost -N '' -f fixtures/privkey-rsa-2048.openssh.pem.3
+node bin/jwk-to-ssh.js fixtures/privkey-rsa-2048.jwk.json root@localhost > fixtures/privkey-rsa-2048.openssh.pem
+node bin/jwk-to-ssh.js fixtures/privkey-rsa-2048.jwk.json root@localhost public > fixtures/pub-rsa-2048.ssh.pub
+
+node bin/jwk-to-ssh.js fixtures/privkey-ec-p256.jwk.json root@localhost > fixtures/privkey-ec-p256.openssh.pem
+node bin/jwk-to-ssh.js fixtures/privkey-ec-p256.jwk.json root@localhost public > fixtures/pub-ec-p256.ssh.pub
+
+node bin/jwk-to-ssh.js fixtures/privkey-ec-p384.jwk.json root@localhost > fixtures/privkey-ec-p384.openssh.pem
+node bin/jwk-to-ssh.js fixtures/privkey-ec-p384.jwk.json root@localhost public > fixtures/pub-ec-p384.ssh.pub
+
+# changes embedded comment and creates new random dummy checksum
+ssh-keygen -c -C root@localhost -f fixtures/privkey-rsa-2048.openssh.pem
+ssh-keygen -c -C root@localhost -f fixtures/privkey-ec-p256.openssh.pem
+ssh-keygen -c -C root@localhost -f fixtures/privkey-ec-p384.openssh.pem
+
+# convert to public key
+ssh-keygen -y -C root@localhost -f fixtures/privkey-rsa-2048.openssh.pem
+ssh-keygen -y -C root@localhost -f fixtures/privkey-ec-p256.openssh.pem
+ssh-keygen -y -C root@localhost -f fixtures/privkey-ec-p384.openssh.pem
+
+diff fixtures/pub-rsa-2048.ssh.pub fixtures/privkey-rsa-2048.openssh.pem.pub
+diff fixtures/pub-ec-p256.ssh.pub fixtures/privkey-ec-p256.openssh.pem.pub
+diff fixtures/pub-ec-p384.ssh.pub fixtures/privkey-ec-p384.openssh.pem.pub
+
+#ssh-keygen -e -m PKCS8 -f fixtures/privkey-ec-p256.openssh.pem
+#ssh-keygen -e -m RFC4716 -f fixtures/privkey-ec-p256.openssh.pem