1 files changed, 100 insertions, 0 deletions
diff --git a/libraries/spongycastle/pg/src/main/java/org/spongycastle/openpgp/operator/bc/BcPublicKeyDataDecryptorFactory.java b/libraries/spongycastle/pg/src/main/java/org/spongycastle/openpgp/operator/bc/BcPublicKeyDataDecryptorFactory.java
new file mode 100644
index 000000000..f4844cabb
--- /dev/null
+++ b/libraries/spongycastle/pg/src/main/java/org/spongycastle/openpgp/operator/bc/BcPublicKeyDataDecryptorFactory.java
@@ -0,0 +1,100 @@
+package org.spongycastle.openpgp.operator.bc;
+
+import org.spongycastle.crypto.AsymmetricBlockCipher;
+import org.spongycastle.crypto.BlockCipher;
+import org.spongycastle.crypto.BufferedAsymmetricBlockCipher;
+import org.spongycastle.crypto.InvalidCipherTextException;
+import org.spongycastle.crypto.params.AsymmetricKeyParameter;
+import org.spongycastle.crypto.params.ElGamalPrivateKeyParameters;
+import org.spongycastle.openpgp.PGPException;
+import org.spongycastle.openpgp.PGPPrivateKey;
+import org.spongycastle.openpgp.PGPPublicKey;
+import org.spongycastle.openpgp.operator.PGPDataDecryptor;
+import org.spongycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
+
+/**
+ * A decryptor factory for handling public key decryption operations.
+ */
+public class BcPublicKeyDataDecryptorFactory
+    implements PublicKeyDataDecryptorFactory
+{
+    private BcPGPKeyConverter keyConverter = new BcPGPKeyConverter();
+    private PGPPrivateKey privKey;
+
+    public BcPublicKeyDataDecryptorFactory(PGPPrivateKey privKey)
+    {
+        this.privKey = privKey;
+    }
+
+    public byte[] recoverSessionData(int keyAlgorithm, byte[][] secKeyData)
+        throws PGPException
+    {
+        try
+        {
+            AsymmetricBlockCipher c = BcImplProvider.createPublicKeyCipher(keyAlgorithm);
+
+            AsymmetricKeyParameter key = keyConverter.getPrivateKey(privKey);
+
+            BufferedAsymmetricBlockCipher c1 = new BufferedAsymmetricBlockCipher(c);
+
+            c1.init(false, key);
+
+            if (keyAlgorithm == PGPPublicKey.RSA_ENCRYPT
+                || keyAlgorithm == PGPPublicKey.RSA_GENERAL)
+            {
+                byte[] bi = secKeyData[0];
+
+                c1.processBytes(bi, 2, bi.length - 2);
+            }
+            else
+            {
+                BcPGPKeyConverter converter = new BcPGPKeyConverter();
+                ElGamalPrivateKeyParameters parms = (ElGamalPrivateKeyParameters) converter.getPrivateKey(privKey);
+                int size = (parms.getParameters().getP().bitLength() + 7) / 8;
+                byte[] tmp = new byte[size];
+
+                byte[] bi = secKeyData[0]; // encoded MPI
+                if (bi.length - 2 > size)  // leading Zero? Shouldn't happen but...
+                {
+                    c1.processBytes(bi, 3, bi.length - 3);
+                }
+                else
+                {
+                    System.arraycopy(bi, 2, tmp, tmp.length - (bi.length - 2), bi.length - 2);
+                    c1.processBytes(tmp, 0, tmp.length);
+                }
+
+                bi = secKeyData[1];  // encoded MPI
+                for (int i = 0; i != tmp.length; i++)
+                {
+                    tmp[i] = 0;
+                }
+
+                if (bi.length - 2 > size) // leading Zero? Shouldn't happen but...
+                {
+                    c1.processBytes(bi, 3, bi.length - 3);
+                }
+                else
+                {
+                    System.arraycopy(bi, 2, tmp, tmp.length - (bi.length - 2), bi.length - 2);
+                    c1.processBytes(tmp, 0, tmp.length);
+                }
+            }
+
+            return c1.doFinal();
+        }
+        catch (InvalidCipherTextException e)
+        {
+            throw new PGPException("exception encrypting session info: " + e.getMessage(), e);
+        }
+
+    }
+
+    public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key)
+        throws PGPException
+    {
+        BlockCipher engine = BcImplProvider.createBlockCipher(encAlgorithm);
+
+        return BcUtil.createDataDecryptor(withIntegrityPacket, engine, key);
+    }
+}