deployd/lib/keys.js

var fs = require('fs')
	,	crypto = require('crypto');

/*!
 * A collection of keys backed by a file.
 */

function Keys(path) {
	this.path = path;
}
module.exports = Keys;

/*!
 * Get a key from the given keys file.
 */

Keys.prototype.get = function(key, fn) {
  this.readFile(function(err, data) {
  	fn(err, data[key]);
  });
}

/*!
 * Generate a key using cryptographically strong pseudo-random data.
 */

Keys.prototype.generate = function() {
	return crypto.randomBytes(256).toString('hex');
}

/*!
 * Create a new key and save it in the keys file.
 */

Keys.prototype.create = function(fn) {
	var key = this.generate()
		,	keys = this;

	this.readFile(function(err, data) {
		if(err) return fn(err);

		data[key] = true;
		keys.writeFile(data, function(err) {
			fn(err, key);
		});
  });
}

/*!
 * Read the contents of the key file as JSON
 */

Keys.prototype.readFile = function(fn) {
	fs.readFile(this.path, 'utf-8', function(err, data) {
    var jsonData
      , error;

    try {
      jsonData = (data && JSON.parse(data)) || {};
    } catch (ex) {
      error = ex;
    }

    fn(error, jsonData);
  });
}


/*!
 * Write the contents of the key file as JSON
 */

Keys.prototype.writeFile = function(data, fn) {
	var str;

	try {
		str = JSON.stringify(data)
	} catch(e) {
		return fn(r);
	}

	fs.writeFile(this.path, str, fn);
}