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bcprov-jdk15on-148.jar和bcpg-jdk15on-148.jar
Bouncy Castle支持大量的密碼術算法，其中包括OpenPGP，引用很廣泛，Pega就是使用Bouncy Castle對郵件和客戶重要數據進行加密解密的。
它既可以安裝成JDK擴展也可以放到特定java項目中使用。

3. 在Oracle官網下載UnlimitedJCEPolicy

4. 編寫代碼

PGPExampleUtil.java

package com.zolly.bouncycastle;

import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.NoSuchProviderException;
import java.util.Iterator;

import org.bouncycastle.openpgp.PGPCompressedDataGenerator;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPLiteralData;
import org.bouncycastle.openpgp.PGPPrivateKey;
import org.bouncycastle.openpgp.PGPPublicKey;
import org.bouncycastle.openpgp.PGPPublicKeyRing;
import org.bouncycastle.openpgp.PGPPublicKeyRingCollection;
import org.bouncycastle.openpgp.PGPSecretKey;
import org.bouncycastle.openpgp.PGPSecretKeyRing;
import org.bouncycastle.openpgp.PGPSecretKeyRingCollection;
import org.bouncycastle.openpgp.PGPUtil;

class PGPExampleUtil
{
    static byte[] compressFile(String fileName, int algorithm) throws IOException
    {
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();
        PGPCompressedDataGenerator comData = new PGPCompressedDataGenerator(algorithm);
        PGPUtil.writeFileToLiteralData(comData.open(bOut), PGPLiteralData.BINARY,
            new File(fileName));
        comData.close();
        return bOut.toByteArray();
    }

    /**
     * Search a secret key ring collection for a secret key corresponding to keyID if it
     * exists.
     * 
     * @param pgpSec a secret key ring collection.
     * @param keyID keyID we want.
     * @param pass passphrase to decrypt secret key with.
     * @return
     * @throws PGPException
     * @throws NoSuchProviderException
     */
    static PGPPrivateKey findSecretKey(PGPSecretKeyRingCollection pgpSec, long keyID, char[] pass)
        throws PGPException, NoSuchProviderException
    {
        PGPSecretKey pgpSecKey = pgpSec.getSecretKey(keyID);

        if (pgpSecKey == null)
        {
            return null;
        }

        return pgpSecKey.extractPrivateKey(pass, "BC");
    }

    static PGPPublicKey readPublicKey(String fileName) throws IOException, PGPException
    {
        InputStream keyIn = new BufferedInputStream(new FileInputStream(fileName));
        PGPPublicKey pubKey = readPublicKey(keyIn);
        keyIn.close();
        return pubKey;
    }

    /**
     * A simple routine that opens a key ring file and loads the first available key
     * suitable for encryption.
     * 
     * @param input
     * @return
     * @throws IOException
     * @throws PGPException
     */
    static PGPPublicKey readPublicKey(InputStream input) throws IOException, PGPException
    {
        PGPPublicKeyRingCollection pgpPub = new PGPPublicKeyRingCollection(
            PGPUtil.getDecoderStream(input));

        //
        // we just loop through the collection till we find a key suitable for encryption, in the real
        // world you would probably want to be a bit smarter about this.
        //

        Iterator keyRingIter = pgpPub.getKeyRings();
        while (keyRingIter.hasNext())
        {
            PGPPublicKeyRing keyRing = (PGPPublicKeyRing)keyRingIter.next();

            Iterator keyIter = keyRing.getPublicKeys();
            while (keyIter.hasNext())
            {
                PGPPublicKey key = (PGPPublicKey)keyIter.next();

                if (key.isEncryptionKey())
                {
                    return key;
                }
            }
        }

        throw new IllegalArgumentException("Can't find encryption key in key ring.");
    }

    static PGPSecretKey readSecretKey(String fileName) throws IOException, PGPException
    {
        InputStream keyIn = new BufferedInputStream(new FileInputStream(fileName));
        PGPSecretKey secKey = readSecretKey(keyIn);
        keyIn.close();
        return secKey;
    }

    /**
     * A simple routine that opens a key ring file and loads the first available key
     * suitable for signature generation.
     * 
     * @param input stream to read the secret key ring collection from.
     * @return a secret key.
     * @throws IOException on a problem with using the input stream.
     * @throws PGPException if there is an issue parsing the input stream.
     */
    static PGPSecretKey readSecretKey(InputStream input) throws IOException, PGPException
    {
        PGPSecretKeyRingCollection pgpSec = new PGPSecretKeyRingCollection(
            PGPUtil.getDecoderStream(input));

        //
        // we just loop through the collection till we find a key suitable for encryption, in the real
        // world you would probably want to be a bit smarter about this.
        //

        Iterator keyRingIter = pgpSec.getKeyRings();
        while (keyRingIter.hasNext())
        {
            PGPSecretKeyRing keyRing = (PGPSecretKeyRing)keyRingIter.next();

            Iterator keyIter = keyRing.getSecretKeys();
            while (keyIter.hasNext())
            {
                PGPSecretKey key = (PGPSecretKey)keyIter.next();

                if (key.isSigningKey())
                {
                    return key;
                }
            }
        }

        throw new IllegalArgumentException("Can't find signing key in key ring.");
    }
}

KeyBasedLargeFileProcessor.java

package com.zolly.bouncycastle;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.NoSuchProviderException;
import java.security.SecureRandom;
import java.security.Security;
import java.util.Iterator;

import org.bouncycastle.bcpg.ArmoredOutputStream;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openpgp.PGPCompressedData;
import org.bouncycastle.openpgp.PGPCompressedDataGenerator;
import org.bouncycastle.openpgp.PGPEncryptedData;
import org.bouncycastle.openpgp.PGPEncryptedDataGenerator;
import org.bouncycastle.openpgp.PGPEncryptedDataList;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPLiteralData;
import org.bouncycastle.openpgp.PGPObjectFactory;
import org.bouncycastle.openpgp.PGPOnePassSignatureList;
import org.bouncycastle.openpgp.PGPPrivateKey;
import org.bouncycastle.openpgp.PGPPublicKey;
import org.bouncycastle.openpgp.PGPPublicKeyEncryptedData;
import org.bouncycastle.openpgp.PGPSecretKeyRingCollection;
import org.bouncycastle.openpgp.PGPUtil;
import org.bouncycastle.openpgp.operator.jcajce.JcePGPDataEncryptorBuilder;
import org.bouncycastle.openpgp.operator.jcajce.JcePublicKeyDataDecryptorFactoryBuilder;
import org.bouncycastle.openpgp.operator.jcajce.JcePublicKeyKeyEncryptionMethodGenerator;
import org.bouncycastle.util.io.Streams;

/**
 * A simple utility class that encrypts/decrypts public key based
 * encryption large files.
 */
public class KeyBasedLargeFileProcessor
{
    public static void decryptFile(
        String inputFileName,
        String keyFileName,
        char[] passwd,
        String defaultFileName)
        throws IOException, NoSuchProviderException
    {
        InputStream in = new BufferedInputStream(new FileInputStream(inputFileName));
        InputStream keyIn = new BufferedInputStream(new FileInputStream(keyFileName));
        decryptFile(in, keyIn, passwd, defaultFileName);
        keyIn.close();
        in.close();
    }
    
    /**
     * decrypt the passed in message stream
     */
    public static void decryptFile(
        InputStream in,
        InputStream keyIn,
        char[]      passwd,
        String      defaultFileName)
        throws IOException, NoSuchProviderException
    {    
        in = PGPUtil.getDecoderStream(in);
        
        try
        {
            PGPObjectFactory        pgpF = new PGPObjectFactory(in);
            PGPEncryptedDataList    enc;

            Object                  o = pgpF.nextObject();
            //
            // the first object might be a PGP marker packet.
            //
            if (o instanceof PGPEncryptedDataList)
            {
                enc = (PGPEncryptedDataList)o;
            }
            else
            {
                enc = (PGPEncryptedDataList)pgpF.nextObject();
            }
            
            //
            // find the secret key
            //
            Iterator                    it = enc.getEncryptedDataObjects();
            PGPPrivateKey               sKey = null;
            PGPPublicKeyEncryptedData   pbe = null;
            PGPSecretKeyRingCollection  pgpSec = new PGPSecretKeyRingCollection(
                PGPUtil.getDecoderStream(keyIn));                                                                 
            
            while (sKey == null && it.hasNext())
            {
                pbe = (PGPPublicKeyEncryptedData)it.next();
                
                sKey = PGPExampleUtil.findSecretKey(pgpSec, pbe.getKeyID(), passwd);
            }
            
            if (sKey == null)
            {
                throw new IllegalArgumentException("secret key for message not found.");
            }
            
            InputStream         clear = pbe.getDataStream(new JcePublicKeyDataDecryptorFactoryBuilder().setProvider("BC").build(sKey));
            
            PGPObjectFactory    plainFact = new PGPObjectFactory(clear);
            
            PGPCompressedData   cData = (PGPCompressedData)plainFact.nextObject();
    
            InputStream         compressedStream = new BufferedInputStream(cData.getDataStream());
            PGPObjectFactory    pgpFact = new PGPObjectFactory(compressedStream);
            
            Object              message = pgpFact.nextObject();
            
            if (message instanceof PGPLiteralData)
            {
                PGPLiteralData ld = (PGPLiteralData)message;

                String outFileName = ld.getFileName();
                if (outFileName.length() == 0)
                {
                    outFileName = defaultFileName;
                }

                InputStream unc = ld.getInputStream();
                OutputStream fOut =  new BufferedOutputStream(new FileOutputStream(outFileName));

                Streams.pipeAll(unc, fOut);

                fOut.close();
            }
            else if (message instanceof PGPOnePassSignatureList)
            {
                throw new PGPException("encrypted message contains a signed message - not literal data.");
            }
            else
            {
                throw new PGPException("message is not a simple encrypted file - type unknown.");
            }

            if (pbe.isIntegrityProtected())
            {
                if (!pbe.verify())
                {
                    System.err.println("message failed integrity check");
                }
                else
                {
                    System.err.println("message integrity check passed");
                }
            }
            else
            {
                System.err.println("no message integrity check");
            }
        }
        catch (PGPException e)
        {
            System.err.println(e);
            if (e.getUnderlyingException() != null)
            {
                e.getUnderlyingException().printStackTrace();
            }
        }
    }

    public static void encryptFile(
        String          outputFileName,
        String          inputFileName,
        String          encKeyFileName,
        boolean         armor,
        boolean         withIntegrityCheck)
        throws IOException, NoSuchProviderException, PGPException
    {
        OutputStream out = new BufferedOutputStream(new FileOutputStream(outputFileName));
        PGPPublicKey encKey = PGPExampleUtil.readPublicKey(encKeyFileName);
        encryptFile(out, inputFileName, encKey, armor, withIntegrityCheck);
        out.close();
    }

    public static void encryptFile(
        OutputStream    out,
        String          fileName,
        PGPPublicKey    encKey,
        boolean         armor,
        boolean         withIntegrityCheck)
        throws IOException, NoSuchProviderException
    {    
        if (armor)
        {
            out = new ArmoredOutputStream(out);
        }
        
        try
        {    
            PGPEncryptedDataGenerator   cPk = new PGPEncryptedDataGenerator(new JcePGPDataEncryptorBuilder(PGPEncryptedData.CAST5).setWithIntegrityPacket(withIntegrityCheck).setSecureRandom(new SecureRandom()).setProvider("BC"));
                
            cPk.addMethod(new JcePublicKeyKeyEncryptionMethodGenerator(encKey).setProvider("BC"));
            
            OutputStream                cOut = cPk.open(out, new byte[1 << 16]);
            
            PGPCompressedDataGenerator  comData = new PGPCompressedDataGenerator(
                                                                    PGPCompressedData.ZIP);
                                                                    
            PGPUtil.writeFileToLiteralData(comData.open(cOut), PGPLiteralData.BINARY, new File(fileName), new byte[1 << 16]);
            
            comData.close();
            
            cOut.close();

            if (armor)
            {
                out.close();
            }
        }
        catch (PGPException e)
        {
            System.err.println(e);
            if (e.getUnderlyingException() != null)
            {
                e.getUnderlyingException().printStackTrace();
            }
        }
    }

    public static void main(
        String[] args)
        throws Exception
    {
        Security.addProvider(new BouncyCastleProvider());
        
        decryptFile("Encypted File.txt.pgp", "Key.asc", "123456789".toCharArray(), "Encypted File.txt");
    }
}