title: how to load the private key from a .der file into java private key object
body: <p>I'm writing a java program to import private keys from files within the file system and make a private key object, using java... 
  I could do it for files in <code>.pem</code> format but, with .der format, I had no idea what to do, since I couldnt firstly detect the algorithm used to generate the keys.
  within <code>.pem</code> files I could determine the algorithm from the header for <code>PKCS#1</code> which have a header like<br>
          <code>-----BEGIN RSA PRIVATE KEY----</code><br>
  formats and used the bouncycastle <code>pem</code> reader for those in PKCS#8 which have a header<br>
  <code>-----BEGIN PRIVATE KEY-----</code>
  but with those in .der format no idea :(<br>
  also if anyone have an idea about <code>.key</code> format tell me<br>
  thanx </p>