code: function Rc4a(key) {
  
    this.key = null;
    this.derivatedKey = null;
    this.ksa = null;
    this.prga = null;
    this.change(key);
  }
docs: /*
  class
   
  Rc4a class
  
  @class Rc4a
  @param {String|Array|Buffer} key - user key
  @return {Object}