1 files changed, 100 insertions, 0 deletions
diff --git a/pg/src/main/java/org/spongycastle/openpgp/operator/PublicKeyKeyEncryptionMethodGenerator.java b/pg/src/main/java/org/spongycastle/openpgp/operator/PublicKeyKeyEncryptionMethodGenerator.java
new file mode 100644
index 00000000..8030b946
--- /dev/null
+++ b/pg/src/main/java/org/spongycastle/openpgp/operator/PublicKeyKeyEncryptionMethodGenerator.java
@@ -0,0 +1,100 @@
+package org.spongycastle.openpgp.operator;
+
+import java.io.IOException;
+import java.math.BigInteger;
+
+import org.spongycastle.bcpg.ContainedPacket;
+import org.spongycastle.bcpg.MPInteger;
+import org.spongycastle.bcpg.PublicKeyEncSessionPacket;
+import org.spongycastle.openpgp.PGPException;
+import org.spongycastle.openpgp.PGPPublicKey;
+
+public abstract class PublicKeyKeyEncryptionMethodGenerator
+    extends PGPKeyEncryptionMethodGenerator
+{
+    private PGPPublicKey pubKey;
+
+    protected PublicKeyKeyEncryptionMethodGenerator(
+        PGPPublicKey pubKey)
+    {
+        this.pubKey = pubKey;
+
+        switch (pubKey.getAlgorithm())
+        {
+        case PGPPublicKey.RSA_ENCRYPT:
+        case PGPPublicKey.RSA_GENERAL:
+            break;
+        case PGPPublicKey.ELGAMAL_ENCRYPT:
+        case PGPPublicKey.ELGAMAL_GENERAL:
+            break;
+        case PGPPublicKey.ECDH:
+            break;
+        case PGPPublicKey.DSA:
+            throw new IllegalArgumentException("Can't use DSA for encryption.");
+        case PGPPublicKey.ECDSA:
+            throw new IllegalArgumentException("Can't use ECDSA for encryption.");
+        default:
+            throw new IllegalArgumentException("unknown asymmetric algorithm: " + pubKey.getAlgorithm());
+        }
+    }
+
+    public byte[][] processSessionInfo(
+        byte[] encryptedSessionInfo)
+        throws PGPException
+    {
+        byte[][] data;
+
+        switch (pubKey.getAlgorithm())
+        {
+        case PGPPublicKey.RSA_ENCRYPT:
+        case PGPPublicKey.RSA_GENERAL:
+            data = new byte[1][];
+
+            data[0] = convertToEncodedMPI(encryptedSessionInfo);
+            break;
+        case PGPPublicKey.ELGAMAL_ENCRYPT:
+        case PGPPublicKey.ELGAMAL_GENERAL:
+            byte[] b1 = new byte[encryptedSessionInfo.length / 2];
+            byte[] b2 = new byte[encryptedSessionInfo.length / 2];
+
+            System.arraycopy(encryptedSessionInfo, 0, b1, 0, b1.length);
+            System.arraycopy(encryptedSessionInfo, b1.length, b2, 0, b2.length);
+
+            data = new byte[2][];
+            data[0] = convertToEncodedMPI(b1);
+            data[1] = convertToEncodedMPI(b2);
+            break;
+        case PGPPublicKey.ECDH:
+            data = new byte[1][];
+
+            data[0] = encryptedSessionInfo;
+            break;
+        default:
+            throw new PGPException("unknown asymmetric algorithm: " + pubKey.getAlgorithm());
+        }
+
+        return data;
+    }
+
+    private byte[] convertToEncodedMPI(byte[] encryptedSessionInfo)
+        throws PGPException
+    {
+        try
+        {
+            return new MPInteger(new BigInteger(1, encryptedSessionInfo)).getEncoded();
+        }
+        catch (IOException e)
+        {
+            throw new PGPException("Invalid MPI encoding: " + e.getMessage(), e);
+        }
+    }
+
+    public ContainedPacket generate(int encAlgorithm, byte[] sessionInfo)
+        throws PGPException
+    {
+        return new PublicKeyEncSessionPacket(pubKey.getKeyID(), pubKey.getAlgorithm(), processSessionInfo(encryptSessionInfo(pubKey, sessionInfo)));
+    }
+
+    abstract protected byte[] encryptSessionInfo(PGPPublicKey pubKey, byte[] sessionInfo)
+        throws PGPException;
+}