1 files changed, 109 insertions, 0 deletions
diff --git a/pg/src/main/java/org/spongycastle/openpgp/operator/jcajce/JcePBEDataDecryptorFactoryBuilder.java b/pg/src/main/java/org/spongycastle/openpgp/operator/jcajce/JcePBEDataDecryptorFactoryBuilder.java
new file mode 100644
index 00000000..d0e73b24
--- /dev/null
+++ b/pg/src/main/java/org/spongycastle/openpgp/operator/jcajce/JcePBEDataDecryptorFactoryBuilder.java
@@ -0,0 +1,109 @@
+package org.spongycastle.openpgp.operator.jcajce;
+
+import java.security.Provider;
+
+import javax.crypto.Cipher;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+
+import org.spongycastle.jcajce.util.DefaultJcaJceHelper;
+import org.spongycastle.jcajce.util.NamedJcaJceHelper;
+import org.spongycastle.jcajce.util.ProviderJcaJceHelper;
+import org.spongycastle.openpgp.PGPException;
+import org.spongycastle.openpgp.operator.PBEDataDecryptorFactory;
+import org.spongycastle.openpgp.operator.PGPDataDecryptor;
+import org.spongycastle.openpgp.operator.PGPDigestCalculatorProvider;
+
+/**
+ * Builder for {@link PBEDataDecryptorFactory} instances that obtain cryptographic primitives using
+ * the JCE API.
+ */
+public class JcePBEDataDecryptorFactoryBuilder
+{
+    private OperatorHelper helper = new OperatorHelper(new DefaultJcaJceHelper());
+    private PGPDigestCalculatorProvider calculatorProvider;
+
+    /**
+     * Base constructor.
+     *
+     * @param calculatorProvider   a digest calculator provider to provide calculators to support the key generation calculation required.
+     */
+    public JcePBEDataDecryptorFactoryBuilder(PGPDigestCalculatorProvider calculatorProvider)
+    {
+        this.calculatorProvider = calculatorProvider;
+    }
+
+    /**
+     * Set the provider object to use for creating cryptographic primitives in the resulting factory the builder produces.
+     *
+     * @param provider  provider object for cryptographic primitives.
+     * @return  the current builder.
+     */
+    public JcePBEDataDecryptorFactoryBuilder setProvider(Provider provider)
+    {
+        this.helper = new OperatorHelper(new ProviderJcaJceHelper(provider));
+
+        return this;
+    }
+
+    /**
+     * Set the provider name to use for creating cryptographic primitives in the resulting factory the builder produces.
+     *
+     * @param providerName  the name of the provider to reference for cryptographic primitives.
+     * @return  the current builder.
+     */
+    public JcePBEDataDecryptorFactoryBuilder setProvider(String providerName)
+    {
+        this.helper = new OperatorHelper(new NamedJcaJceHelper(providerName));
+
+        return this;
+    }
+
+    /**
+     * Construct a {@link PBEDataDecryptorFactory} to use to decrypt PBE encrypted data.
+     *
+     * @param passPhrase the pass phrase to use to generate keys in the resulting factory.
+     * @return a decryptor factory that can be used to generate PBE keys.
+     */
+    public PBEDataDecryptorFactory build(char[] passPhrase)
+    {
+         return new PBEDataDecryptorFactory(passPhrase, calculatorProvider)
+         {
+             public byte[] recoverSessionData(int keyAlgorithm, byte[] key, byte[] secKeyData)
+                 throws PGPException
+             {
+                 try
+                 {
+                     if (secKeyData != null && secKeyData.length > 0)
+                     {
+                         String cipherName = PGPUtil.getSymmetricCipherName(keyAlgorithm);
+                         Cipher keyCipher = helper.createCipher(cipherName + "/CFB/NoPadding");
+
+                         keyCipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, cipherName), new IvParameterSpec(new byte[keyCipher.getBlockSize()]));
+
+                         return keyCipher.doFinal(secKeyData);
+                     }
+                     else
+                     {
+                         byte[] keyBytes = new byte[key.length + 1];
+
+                         keyBytes[0] = (byte)keyAlgorithm;
+                         System.arraycopy(key, 0, keyBytes, 1, key.length);
+
+                         return keyBytes;
+                     }
+                 }
+                 catch (Exception e)
+                 {
+                     throw new PGPException("Exception recovering session info", e);
+                 }
+             }
+
+             public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key)
+                 throws PGPException
+             {
+                 return helper.createDataDecryptor(withIntegrityPacket, encAlgorithm, key);
+             }
+         };
+    }
+}