title: How can I read a BouncyCastle private key PEM file using JCA?
body: <p>In one of our applications private keys are stored using BouncyCastle's PEMWriter. At the moment I am investigating if we can get rid of the BouncyCastle dependency since Java 7 seems to have everything we need. The only issue is that I can not read the private keys stored in the database as PEM-encoded strings (the certificates/public keys are fine).</p>
  
  <p>If I save the PEM-encoded string of the private key from the database to a file I can run OpenSSL to convert the key to PKCS#8 format like this:</p>
  
  <pre><code>openssl pkcs8 -topk8 -inform PEM -outform DER \
                -in private_key.pem -out private_key.der -nocrypt
  </code></pre>
  
  <p>The resulting output I can base64 encode and then read using this bit of Java/JCA code:</p>
  
  <pre><code>byte[] privateKeyBytes = 
             DatatypeConverter.parseBase64Binary(privateKeyDERcontents);
  PrivateKey prKey = 
             KeyFactory.getInstance("RSA").
                 generatePrivate(new PKCS8EncodedKeySpec(privateKeyBytes));
  </code></pre>
  
  <p>This private key matches the public key stored as expected, i.e. I can round-trip from plaintext to ciphertext and back.</p>
  
  <p>The question I have is: can I directly read the original PEM encoding somehow?</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>Here is a bit of code that reads the strings in question using BouncyCastle:</p>
  
  <pre><code>if (Security.getProvider("BC") == null) {
      Security.addProvider(new BouncyCastleProvider());
  }
  PEMReader pemReader = new PEMReader(new StringReader(privateKeyPEM));
  KeyPair keyPair = (KeyPair) pemReader.readObject();
  PrivateKey key = keyPair.getPrivate();
  </code></pre>
  
  <p>The "privateKeyPEM" is the PEM encoded string in the database, otherwise this example is self-contained. Interestingly it already uses the JCA KeyPair object as output. To rephrase my original question: can I do the equivalent of the code above without depending on PEMReader (and in turn quite a few other BouncyCastle classes)?</p>