Registering multiple keystores in JVM

Question

I have two applications running in the same java virtual machine, and both use different keystores and truststores.

A viable option would be use a single keystore an

Answer 1

After playing with the code I have received from ZZ Coder, sylvarking and Software Monkey, I have found a solution that works:

First, I wrote a X509KeyManager that works combines a custom keystore and a default keystore.

class MultiKeyStoreManager implements X509KeyManager {
 private static final Logger logger = Logger.getLogger(MultiKeyStoreManager.class); 
 private final X509KeyManager jvmKeyManager;
 private final X509KeyManager customKeyManager;

 public MultiKeyStoreManager(X509KeyManager jvmKeyManager, X509KeyManager customKeyManager ) {
  this.jvmKeyManager = jvmKeyManager;
  this.customKeyManager = customKeyManager;  
 }

 @Override
 public String chooseClientAlias(String[] keyType, Principal[] issuers, Socket socket) {
  // try the first key manager
  String alias = customKeyManager.chooseClientAlias(keyType, issuers, socket);
  if( alias == null ) {
   alias = jvmKeyManager.chooseClientAlias(keyType, issuers, socket);
   logger.warn("Reverting to JVM CLIENT alias : " + alias);
  }

  return alias;

 }

 @Override
 public String chooseServerAlias(String keyType, Principal[] issuers, Socket socket) {
  // try the first key manager
  String alias = customKeyManager.chooseServerAlias(keyType, issuers, socket);
  if( alias == null ) {
   alias =  jvmKeyManager.chooseServerAlias(keyType, issuers, socket);
   logger.warn("Reverting to JVM Server alias : " + alias);
  } 
  return alias;
 }

 @Override
 public X509Certificate[] getCertificateChain(String alias) {
  X509Certificate[] chain = customKeyManager.getCertificateChain(alias);
  if( chain == null || chain.length == 0) {
   logger.warn("Reverting to JVM Chain : " + alias);
   return jvmKeyManager.getCertificateChain(alias);
  } else {
   return chain;
  }  
 }

 @Override
 public String[] getClientAliases(String keyType, Principal[] issuers) {
  String[] cAliases = customKeyManager.getClientAliases(keyType, issuers);
  String[] jAliases = jvmKeyManager.getClientAliases(keyType, issuers);
  logger.warn("Supported Client Aliases Custom: " + cAliases.length + " JVM : " + jAliases.length);
  return ArrayUtils.join(cAliases,jAliases);
 }

 @Override
 public PrivateKey getPrivateKey(String alias) {
  PrivateKey key = customKeyManager.getPrivateKey(alias);
  if( key == null ) {
   logger.warn("Reverting to JVM Key : " + alias);
   return jvmKeyManager.getPrivateKey(alias);
  } else {
   return key;
  }
 }

 @Override
 public String[] getServerAliases(String keyType, Principal[] issuers) {
  String[] cAliases = customKeyManager.getServerAliases(keyType, issuers);
  String[] jAliases = jvmKeyManager.getServerAliases(keyType, issuers);
  logger.warn("Supported Server Aliases Custom: " + cAliases.length + " JVM : " + jAliases.length);
  return ArrayUtils.join(cAliases,jAliases);
 }

}

Then, you can use this keystore manager when creating an SSL Context or SocketFactory. The code needs some refactoring and tidying up but it works perfectly.

 /**
  * Returns an array of KeyManagers, set up to use the required keyStore.
  * This method does the bulk of the work of setting up the custom trust managers.
  * 
  * @param props 
  * 
  * @return an array of KeyManagers set up accordingly.
  */
 private static KeyManager[] getKeyManagers(Properties props) throws IOException, GeneralSecurityException {
  // First, get the default KeyManagerFactory.
  String alg = KeyManagerFactory.getDefaultAlgorithm();
  KeyManagerFactory kmFact = KeyManagerFactory.getInstance(alg);   
  // Next, set up the KeyStore to use. We need to load the file into
  // a KeyStore instance.
  FileInputStream fis = new FileInputStream(props.getProperty(SSL_KEYSTORE));
  logger.info("Loaded keystore");
  KeyStore ks = KeyStore.getInstance("jks");
  String keyStorePassword = props.getProperty(SSL_KEYSTORE_PASSWORD);
  ks.load(fis, keyStorePassword.toCharArray());
  fis.close();
  // Now we initialise the KeyManagerFactory with this KeyStore
  kmFact.init(ks, keyStorePassword.toCharArray());

  // default
  KeyManagerFactory dkmFact = KeyManagerFactory.getInstance(alg); 
  dkmFact.init(null,null);  

  // Get the first X509KeyManager in the list
  X509KeyManager customX509KeyManager = getX509KeyManager(alg, kmFact);
  X509KeyManager jvmX509KeyManager = getX509KeyManager(alg, dkmFact);

  KeyManager[] km = { new MultiKeyStoreManager(jvmX509KeyManager, customX509KeyManager) };   
  logger.debug("Number of key managers registered:" + km.length);  
  return km;
 }


 /**
  * Find a X509 Key Manager compatible with a particular algorithm
  * @param algorithm
  * @param kmFact
  * @return
  * @throws NoSuchAlgorithmException
  */
 private static X509KeyManager getX509KeyManager(String algorithm, KeyManagerFactory kmFact)
   throws NoSuchAlgorithmException {
  KeyManager[] keyManagers = kmFact.getKeyManagers();

  if (keyManagers == null || keyManagers.length == 0) {
   throw new NoSuchAlgorithmException("The default algorithm :" + algorithm + " produced no key managers");
  }

  X509KeyManager x509KeyManager = null;

  for (int i = 0; i < keyManagers.length; i++) {
   if (keyManagers[i] instanceof X509KeyManager) {
    x509KeyManager = (X509KeyManager) keyManagers[i];
    break;
   }
  }

  if (x509KeyManager == null) {
   throw new NoSuchAlgorithmException("The default algorithm :"+ algorithm + " did not produce a X509 Key manager");
  }
  return x509KeyManager;
 }




 private static void initialiseManager(Properties props) throws IOException, GeneralSecurityException { 
  // Next construct and initialise a SSLContext with the KeyStore and
  // the TrustStore. We use the default SecureRandom.
  SSLContext context = SSLContext.getInstance("SSL");
  context.init(getKeyManagers(props), getTrustManagers(props), null);
  SSLContext.setDefault(context);

 }

Let me know if anyone has any question or need any demonstration codes.