pgp encryption util added

src/core/java/org/wyona/yanel/core/util/PGPEncryptionUtil.java

@@ -0,0 +1,91 @@
+package org.wyona.yanel.core.util;
+
+import org.bouncycastle.bcpg.ArmoredOutputStream;
+import org.bouncycastle.openpgp.*;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.security.NoSuchProviderException;
+import java.security.SecureRandom;
+import java.util.Date;
+
+/**
+ *
+ */
+public class PGPEncryptionUtil {
+
+    private static final String BC_PROVIDER_NAME = "BC";
+
+    // pick some sensible encryption buffer size
+    private static final int BUFFER_SIZE = 4096;
+
+    // encrypt the payload data using AES-256,
+    // remember that PGP uses a symmetric key to encrypt
+    // data and uses the public key to encrypt the symmetric
+    // key used on the payload.
+    private static final int PAYLOAD_ENCRYPTION_ALG = PGPEncryptedData.AES_256;
+
+    // various streams we're taking care of
+    private final ArmoredOutputStream armoredOutputStream;
+    private final OutputStream encryptedOut;
+    private final OutputStream compressedOut;
+    private final OutputStream literalOut;
+
+    /**
+     * @param payloadFilename Filename which will be used for decrypted message
+     * @param out Output stream where encryped data will be written to
+     */
+    public PGPEncryptionUtil(PGPPublicKey key, String payloadFilename, OutputStream out) throws PGPException, NoSuchProviderException, IOException {
+
+        // write data out using "ascii-armor" encoding.  This is the
+        // normal PGP text output.
+        this.armoredOutputStream = new ArmoredOutputStream(out);
+
+        // create an encrypted payload and set the public key on the data generator
+        PGPEncryptedDataGenerator encryptGen = new PGPEncryptedDataGenerator(PAYLOAD_ENCRYPTION_ALG,
+                                                              new SecureRandom(), BC_PROVIDER_NAME);
+        encryptGen.addMethod(key);
+
+        // open an output stream connected to the encrypted data generator
+        // and have the generator write its data out to the ascii-encoding stream
+        this.encryptedOut = encryptGen.open(armoredOutputStream, BUFFER_SIZE);
+
+        // compress data.  we are building layers of output streams.  we want to compress here
+        // because this is "before" encryption, and you get far better compression on
+        // unencrypted data.
+        PGPCompressedDataGenerator compressor = new PGPCompressedDataGenerator(PGPCompressedData.ZIP);
+        this.compressedOut = compressor.open(encryptedOut);
+
+        // now we have a stream connected to a data compressor, which is connected to
+        // a data encryptor, which is connected to an ascii-encoder.
+        // into that we want to write a PGP "literal" object, which is just a named
+        // piece of data (as opposed to a specially-formatted key, signature, etc)
+        PGPLiteralDataGenerator literalGen = new PGPLiteralDataGenerator();
+        this.literalOut = literalGen.open(compressedOut, PGPLiteralDataGenerator.UTF8,
+                                          payloadFilename, new Date(), new byte[BUFFER_SIZE]);
+    }
+
+    /**
+     * Get an output stream connected to the encrypted file payload.
+     */
+    public OutputStream getPayloadOutputStream() {
+        return this.literalOut;
+    }
+
+    /**
+     * Close the encrypted output writers.
+     */
+    public void close() throws IOException {
+        // close the literal output
+        literalOut.close();
+
+        // close the compressor
+        compressedOut.close();
+
+        // close the encrypted output
+        encryptedOut.close();
+
+        // close the armored output
+        armoredOutputStream.close();
+    }
+}