DerUtils.java

package org.keycloak;

import java.io.DataInputStream;
import java.io.InputStream;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

/**
 * Extract PrivateKey, PublicKey, and X509Certificate from a DER encoded byte array or file.  Usually
 * generated from openssl
 *
 * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
 * @version $Revision: 1 $
 */
public class DerUtils
{
   static
   {
      BouncyIntegration.init();
   }

   public static PrivateKey decodePrivateKey(InputStream is)
           throws Exception
   {

      DataInputStream dis = new DataInputStream(is);
      byte[] keyBytes = new byte[dis.available()];
      dis.readFully(keyBytes);
      dis.close();

      PKCS8EncodedKeySpec spec =
              new PKCS8EncodedKeySpec(keyBytes);
      KeyFactory kf = KeyFactory.getInstance("RSA", "BC");
      return kf.generatePrivate(spec);
   }

   public static PublicKey decodePublicKey(byte[] der) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchProviderException
   {
      X509EncodedKeySpec spec =
              new X509EncodedKeySpec(der);
      KeyFactory kf = KeyFactory.getInstance("RSA", "BC");
      return kf.generatePublic(spec);
   }

   public static X509Certificate decodeCertificate(InputStream is) throws Exception
   {
      CertificateFactory cf = CertificateFactory.getInstance("X.509", "BC");
      X509Certificate cert = (X509Certificate) cf.generateCertificate(is);
      is.close();
      return cert;
   }

   public static PrivateKey decodePrivateKey(byte[] der) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchProviderException
   {
      PKCS8EncodedKeySpec spec =
              new PKCS8EncodedKeySpec(der);
      KeyFactory kf = KeyFactory.getInstance("RSA", "BC");
      return kf.generatePrivate(spec);
   }
}