added provision for default setting of digest calculator provider to …

…the JcePBEDataDecryptorFactoryBuilder

pg/src/main/java/org/bouncycastle/openpgp/operator/jcajce/JcaPGPDigestCalculatorProviderBuilder.java

@@ -33,6 +33,11 @@ public JcaPGPDigestCalculatorProviderBuilder()
     {
     }
 
+    JcaPGPDigestCalculatorProviderBuilder(OperatorHelper helper)
+    {
+        this.helper = helper;
+    }
+
     /**
      * Sets the provider to use to obtain cryptographic primitives.
      *

pg/src/main/java/org/bouncycastle/openpgp/operator/jcajce/JcePBEDataDecryptorFactoryBuilder.java

@@ -24,6 +24,15 @@ public class JcePBEDataDecryptorFactoryBuilder
     private OperatorHelper helper = new OperatorHelper(new DefaultJcaJceHelper());
     private PGPDigestCalculatorProvider calculatorProvider;
 
+    /**
+     * Base constructor - assume the required digest calculators can be provided from the same source as
+     * the cipher needed.
+     */
+    public JcePBEDataDecryptorFactoryBuilder()
+    {
+        this.calculatorProvider = null;
+    }
+
     /**
      * Base constructor.
      *
@@ -68,6 +77,17 @@ public JcePBEDataDecryptorFactoryBuilder setProvider(String providerName)
      */
     public PBEDataDecryptorFactory build(char[] passPhrase)
     {
+         if (calculatorProvider == null)
+         {
+             try
+             {
+                 calculatorProvider = new JcaPGPDigestCalculatorProviderBuilder(helper).build();
+             }
+             catch (PGPException e)
+             {
+                 throw new IllegalStateException("digest calculator provider cannot be built with current helper: " + e.getMessage());
+             }
+         }
          return new PBEDataDecryptorFactory(passPhrase, calculatorProvider)
          {
              public byte[] recoverSessionData(int keyAlgorithm, byte[] key, byte[] secKeyData)