OF-946: Help Java to find the correct Security Provider

For some reason, the default validation fails to iterate over all providers and will fail if the default
provider does not support the algorithm of the chain. To work around this issue, the code now iterates over
each provider explicitly, returning success when at least one provider validates the chain successfully.
This replaces an earlier attempt to fix this issue by explicitly naming one (and just one) provider.

src/java/org/jivesoftware/openfire/keystore/IdentityStoreConfig.java

@@ -49,7 +49,7 @@ public class IdentityStoreConfig extends CertificateStoreConfig
 
         try
         {
-            keyFactory = KeyManagerFactory.getInstance( KeyManagerFactory.getDefaultAlgorithm(), PROVIDER );
+            keyFactory = KeyManagerFactory.getInstance( KeyManagerFactory.getDefaultAlgorithm() );
             keyFactory.init( store, password.toCharArray() );
         }
         catch ( UnrecoverableKeyException | NoSuchAlgorithmException | KeyStoreException ex )

src/java/org/jivesoftware/openfire/keystore/TrustStoreConfig.java

@@ -11,6 +11,7 @@ import java.io.IOException;
 import java.security.KeyStoreException;
 import java.security.NoSuchAlgorithmException;
 import java.security.Provider;
+import java.security.Security;
 import java.security.cert.*;
 import java.util.*;
 
@@ -38,8 +39,8 @@ public class TrustStoreConfig extends CertificateStoreConfig
 
         try
         {
-            certPathValidator = CertPathValidator.getInstance( "PKIX", PROVIDER );
-            certificateFactory = CertificateFactory.getInstance( "X.509", PROVIDER );
+            certPathValidator = CertPathValidator.getInstance( "PKIX" );
+            certificateFactory = CertificateFactory.getInstance( "X.509" );
             trustFactory = TrustManagerFactory.getInstance( TrustManagerFactory.getDefaultAlgorithm() );
             trustFactory.init( store );
         }
@@ -106,23 +107,33 @@ public class TrustStoreConfig extends CertificateStoreConfig
             return false;
         }
 
+        // For some reason, the default validation fails to iterate over all providers and will fail if the default
+        // provider does not support the algorithm of the chain. To work around this issue, this code iterates over
+        // each provider explicitly, returning success when at least one provider validates the chain successfully.
+        Log.debug( "Iterating over all available security providers in order to validate a certificate chain." );
+        for (Provider p : Security.getProviders())
+        {
             try
             {
                 final Set<TrustAnchor> trustAnchors = getAllValidTrustAnchors();
                 final CertPath certPath = getCertPath( chain );
 
-            final PKIXParameters pkixp = new PKIXParameters( trustAnchors );
-            pkixp.setRevocationEnabled( false ); // TODO: enable revocation list validation.
+                final PKIXParameters parameters = new PKIXParameters( trustAnchors );
+                parameters.setRevocationEnabled( false ); // TODO: enable revocation list validation.
+                parameters.setSigProvider( p.getName() ); // Explicitly iterate over each signature provider. See comment above.
+
+                certPathValidator.validate( certPath, parameters );
 
-            certPathValidator.validate( certPath, pkixp );
+                Log.debug( "Provider "+p.getName()+": Able to validate certificate chain." );
+                return true;
             }
             catch ( Exception ex )
             {
-            Log.info( "Unable to trust certificate chain.", ex );
-            return false;
+                Log.debug( "Provider "+p.getName()+": Unable to validate certificate chain.", ex );
+            }
         }
 
-        return true;
+        return false;
     }
 
     /**