具體的給一個我寫的Util類，在這裡使用到了第三方包cryptix,具體的可以去www.cryptix.org網站上去找資料。ceryptix的jar包放在附件中。
示例類：

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.NoSuchAlgorithmException;
import java.security.Security;
import java.security.UnrecoverableKeyException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;


import cryptix.message.EncryptedMessage;
import cryptix.message.EncryptedMessageBuilder;
import cryptix.message.KeyBundleMessage;
import cryptix.message.LiteralMessage;
import cryptix.message.LiteralMessageBuilder;
import cryptix.message.Message;
import cryptix.message.MessageException;
import cryptix.message.MessageFactory;
import cryptix.message.NotEncryptedToParameterException;
import cryptix.message.SignedMessage;
import cryptix.message.SignedMessageBuilder;
import cryptix.openpgp.PGPArmouredMessage;
import cryptix.pki.KeyBundle;

public class PGPUtil {

	/**
	 * 新增提供者
	 */
	static{
		Security.addProvider(new cryptix.jce.provider.CryptixCrypto());
	    Security.addProvider(new cryptix.openpgp.provider.CryptixOpenPGP() );
	}

	/**
	 * 構建 LiteralMessage 物件
	 * @param message		
	 * @return
	 * @throws MessageException
	 */
	private static LiteralMessage buildLiteralMessage(byte[] message) throws MessageException{
		LiteralMessageBuilder lmb = null;

		try {
			lmb = LiteralMessageBuilder.getInstance("OpenPGP");
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		lmb.init(message);
		LiteralMessage literal = (LiteralMessage)lmb.build();
		return literal;
	}

	/**
	 * 使用多個公鑰對明文加密
	 * @param plain			明文
	 * @param recipientKeys	公鑰集合
	 * @return				加密後的明文
	 * @throws MessageException
	 */
	public static byte[] encrypt(byte[] plain,List<KeyBundle> recipientKeys) throws MessageException{
		LiteralMessage literal = buildLiteralMessage(plain);

		EncryptedMessageBuilder emb = null;
		try {
			emb = EncryptedMessageBuilder.getInstance("OpenPGP");
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		emb.init(literal);

		//新增接受者
		for(KeyBundle key : recipientKeys){
			emb.addRecipient(key);
		}
		//壓縮
		emb.setAttribute("compressed", "true");
		//得到加密資訊
		Message msg = emb.build();
		PGPArmouredMessage pgpMsg = new PGPArmouredMessage(msg);
		return pgpMsg.getEncoded();
	}

	/**
	 * 使用單張公鑰加密
	 * @param plain		明文	
	 * @param publicKey	公鑰
	 * @return	返回加密後的密文
	 * @throws MessageException
	 */
	public static byte[] encrypt(byte[] plain,KeyBundle publicKey) throws MessageException{
		List<KeyBundle> list = new ArrayList<KeyBundle>();
		list.add(publicKey);
		return encrypt(plain, list);

	}

	/**
	 * 使用私鑰和密碼對明文簽名
	 * @param plain			明文
	 * @param privateKey	私鑰
	 * @param keypass		私鑰密碼
	 * @return				簽名後的明文
	 * @throws MessageException
	 * @throws UnrecoverableKeyException
	 */
	public static byte[] sign(byte[] plain,KeyBundle privateKey,String keypass)throws MessageException,UnrecoverableKeyException{
        SignedMessageBuilder smb = null;
		try {
			smb = SignedMessageBuilder.getInstance("OpenPGP");
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}

        // SignedMessageBuilder smb = SignedMessageBuilder.getInstance("OpenPGP/V3");

        LiteralMessage literal = buildLiteralMessage(plain);
        smb.init(literal);
        smb.addSigner(privateKey, keypass.toCharArray());

        Message msg = smb.build();
        PGPArmouredMessage armoured = new PGPArmouredMessage(msg);
		return armoured.getEncoded();
	}

	/**
	 * 使用私鑰和密碼解密加密後的資料
	 * @param encrypted		PGP加密過的資料
	 * @param privateKey	私鑰
	 * @param keypass		私鑰密碼
	 * @return				解密後的明文
	 * @throws MessageException
	 * @throws IOException
	 * @throws UnrecoverableKeyException
	 * @throws NotEncryptedToParameterException
	 */
	public static byte[] decrypt(byte[] encrypted,KeyBundle privateKey,String keypass) throws MessageException, IOException, UnrecoverableKeyException, NotEncryptedToParameterException{

		MessageFactory mf = null;
		try {
			mf = MessageFactory.getInstance("OpenPGP");
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}

		Collection msgs = mf.generateMessages(new ByteArrayInputStream(encrypted));

		//得到集合中的EncryptedMessage物件
		Message message = (Message)msgs.iterator().next();

		if (!(message instanceof EncryptedMessage)) {
            throw new MessageException("Not a encrypted message.");
        }

		EncryptedMessage em = (EncryptedMessage)message;
		Message msg = em.decrypt(privateKey,keypass.toCharArray());
		return ((LiteralMessage)msg).getBinaryData();
	}

	/**
	 * 解密驗籤
	 * @param encrypted		密文	
	 * @param privateKey	私鑰
	 * @param keypass		私鑰密碼
	 * @param publicKey		公鑰
	 * @return				返回明文
	 * @throws UnrecoverableKeyException
	 * @throws MessageException
	 * @throws IOException
	 * @throws NotEncryptedToParameterException
	 */
	public static byte[] decryptVerify(byte[] encrypted,KeyBundle privateKey,String keypass,KeyBundle publicKey) throws UnrecoverableKeyException, MessageException, IOException, NotEncryptedToParameterException{
		return PGPUtil.verify(PGPUtil.decrypt(encrypted, privateKey, keypass), publicKey);
	}

	/**
	 * 驗證Message
	 * @param signed	驗證的內容
	 * @param publickey	公鑰
	 * @return			返回驗證後的內容
	 * @throws MessageException
	 * @throws IOException
	 */
	public static byte[] verify(byte[] signed,KeyBundle publickey) throws MessageException, IOException{

		MessageFactory mf = null;
		try {
			mf = MessageFactory.getInstance("OpenPGP");
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}

        Message msg = (Message)mf.generateMessages(new ByteArrayInputStream(signed)).iterator().next();
        if (!(msg instanceof SignedMessage)) {
            throw new MessageException(" Not a signed message.");
        }

        SignedMessage sm = (SignedMessage)msg;
        if (sm.verify(publickey)) {

        } else {
        	throw new MessageException(" Signature verify fail. ");
        }

        if (!(sm.getContents() instanceof LiteralMessage)){
        	throw new MessageException(" Not a signed message.");
        }

        LiteralMessage lm = (LiteralMessage)sm.getContents();
		return lm.getBinaryData();
	}

	/**
	 * 流轉換為PGP KeuBundle 物件
	 * @param inputStream 	Key
	 * @return	轉換後的 KeuBundle
	 * @throws MessageException
	 * @throws IOException
	 */
	public static KeyBundle streamToKeyBundle(InputStream inputStream) throws MessageException, IOException {
		MessageFactory messageFactory = null;
		try {
			messageFactory = MessageFactory.getInstance("OpenPGP");
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		Collection msgs = messageFactory.generateMessages(inputStream);
		KeyBundleMessage keybm = (KeyBundleMessage)msgs.iterator().next();

		return keybm.getKeyBundle();

	}

	/**
	 * 簽名加密
	 * @param plain			明文	
	 * @param privateKey	私鑰	
	 * @param keypass		私鑰密碼
	 * @param recipientKeys	公鑰
	 * @return				返回簽名加密後的資料
	 * @throws UnrecoverableKeyException
	 * @throws MessageException
	 */
	public static byte [] signAndEncrypt(byte[] plain,KeyBundle privateKey,String keypass,List<KeyBundle> recipientKeys) throws UnrecoverableKeyException, MessageException{
		return PGPUtil.encrypt(PGPUtil.sign(plain, privateKey, keypass),recipientKeys);
	}

	/**
	 * 簽名加密
	 * @param plain			明文	
	 * @param privateKey	私鑰	
	 * @param keypass		私鑰密碼
	 * @param recipientKeys	公鑰
	 * @return				返回簽名加密後的資料
	 * @throws UnrecoverableKeyException
	 * @throws MessageException
	 */
	public static byte [] signAndEncrypt(byte[] plain,KeyBundle privateKey,String keypass,KeyBundle publicKey) throws UnrecoverableKeyException, MessageException{
		return PGPUtil.encrypt(PGPUtil.sign(plain, privateKey, keypass),publicKey);
	}
}

 

需要修改jre裡面的security下面的local_policy.jar包給替換。
替換為附件中的local_policy.jar包，然後找到security檔案下面的java.security檔案，在檔案中新增下面的內容：
security.provider.10=cryptix.jce.provider.CryptixCrypto
security.provider.11=cryptix.openpgp.provider.CryptixOpenPGP
增加java的cryptix提供者，sun提供的jre的security下面的local_policy.jar不提供cryptix的加密演算法。
在附件中的testCert.jar是用來測試的公鑰和私鑰。