jeffrey.js

var chatData = JSON.stringify({
      timestamp: (currentDate.getTime() - currentDate.getMilliseconds()) / 1000
    , chat: {
        employee_id: employeeId
      , created_at: chat.created_at
      , username: chat.chatname
      , message: chat.message
    }
});

var chatString = JSON.stringify({
  data: chatData,
  signature: self.signData(chatData)
});

var chatToken = new Buffer(chatString, 'utf-8').toString('base64');

Jeffrey.prototype.signData = function(data) {
  var self = this;
  return crypto.createHash('sha256').update(new Buffer(data + self.settings.private_salt)).digest("hex");
}

Jeffrey.prototype.getDataFromToken = function(token) {
  var self = this;
  
  var json = JSON.parse(new Buffer(token, 'base64').toString('utf-8'));
  if (json.signature == self.signData(json.data)) {
    var data = JSON.parse(json.data);
    var tokenDate = new Date(data['timestamp'] * 1000);
    var expirationDate = new Date(new Date() - 7 * 24 * 3600 * 1000);
    if (tokenDate > expirationDate) {
      return data;
    }
    return false;
  }
}

jeffrey.rb

class JeffreyToken  
  def self.get_token_for_employee(employee, options = {})
    current_time = options[:current_time] || Time.now
    data = { 
      :employee_id => employee.id,
      :chatname => employee.chatname,
      :timestamp => current_time.to_i,
    }.to_json
    
    signature = sign(data)
    
    json = { :data => data, :signature => signature }.to_json
    
    [json].pack("m").gsub("\n", '')
  end
  
  def self.get_data_from_token(token)
    raise InvalidToken if token.blank?
    json = ActiveSupport::JSON.decode(token.unpack("m").first)
    if json['signature'] == sign(json['data'])
      data = ActiveSupport::JSON.decode(json['data'])
      if data['timestamp'].to_i > 1.week.ago.to_i
        return data
      end
    end
    raise InvalidToken
  end
  
  private
  def self.sign(data)
    Digest::SHA256.hexdigest(data + Rails::Jeffrey['shared_password'])
  end
  
  class InvalidToken < StandardError; end;
end