title: RSA: Get exponent and modulus given a public key
body: <p>I need to encrypt some data using RSA in JavaScript. All of the libraries around ask for an exponent and a modulus, yet I get a single <code>public.key</code> file from my opponent. </p>
  
  <p>How do you retrieve the public <code>exponent</code> and <code>modulus</code> part from an RSA file?</p>