add PEM parser / packer

lib/pem-packer.js

@@ -0,0 +1,13 @@
+'use strict';
+
+var PEM = module.exports;
+var Enc = require('./encoding.js');
+
+PEM.packBlock = function (opts) {
+  var n = opts.lineLength || 64;
+  var re = new RegExp('.{1,' + n + '}', 'g');
+  return '-----BEGIN ' + opts.type + '-----\n'
+    + Enc.bufToBase64(opts.bytes).match(re).join('\n') + '\n'
+    + '-----END ' + opts.type + '-----'
+  ;
+};

lib/pem-parser.js

@@ -0,0 +1,21 @@
+'use strict';
+
+var PEM = module.exports;
+var Enc = require('./encoding.js');
+
+PEM.parseBlock = function pemToDer(pem) {
+  var lines = pem.trim().split(/\n/);
+  var end = lines.length - 1;
+  var head = lines[0].match(/-----BEGIN (.*)-----/);
+  var foot = lines[end].match(/-----END (.*)-----/);
+
+  if (head) {
+    lines = lines.slice(1, end);
+    head = head[1];
+    if (head !== foot[1]) {
+      throw new Error("headers and footers do not match");
+    }
+  }
+
+  return { type: head, bytes: Enc.base64ToBuf(lines.join('')) };
+};