Openssl wrapper for nodejs

openssl.js

'use strict';
var spawn = require('child_process').spawn,
    Promise = require('bluebird'),
    _ = require('underscore'),
    concat = require('concat-stream');
  
var o = module.exports = {};
  
o.req = function(privKeyPem, subjectData) {
  return new Promise(function(resolve, reject) {
    var subjStr = '/' + _.pairs(subjectData).map(function(p) { return p.join('='); }).join('/') + '/';
    var openSsl = spawn('openssl', ['req', '-outform', 'DER', '-key', '/dev/stdin', '-subj', subjStr, '-new']);
    openSsl.stdout.pipe(concat(function(str) {
      if (!str.length) return;
      resolve(str);
    }));
    openSsl.stderr.pipe(concat(function(str) {
      reject(str.toString('utf8'));
    }));
    openSsl.stdin.write(privKeyPem);
    openSsl.stdin.end();
  });
};