OpenPGP加密解密文件

OpenPGP 号称是世界上使用最广泛的邮件加密标准. OpenPGP is the most widely used email encryption standard in the world. ( http://www.openpgp.org/ )
这篇例子介绍如何使用这个标准进行文件的加密解密 (https://www.bouncycastle.org/latest_releases.html, 需要下载: bcprov-jdk15on-151.jar, bcpg-jdk15on-151.jar).

主要是使用bouncycastle提供的OpenPGP的库来完成这个功能，参照了其提供的示例程序，进行了部分改动 ( Bouncy Castle 是一种用于 Java 平台的开放源码的轻量级密码术包。它支持大量的密码术算法，并提供 JCE 1.2.1 的实现。因为 Bouncy Castle 被设计成轻量级的，所以从 J2SE 1.4 到 J2ME（包括 MIDP）平台，它都可以运行。它是在 MIDP 上运行的唯一完整的密码术包。)
1. 添加循环遍历来查找第一个可用的message
2. 需要注意的是在main函数中的，如果不添加这一句的话 Security.addProvider(new BouncyCastleProvider()); 程序运行中会报错：No such Provider "BC"
3. 错误Exception in thread "main" java.security.InvalidKeyException: Illegal key size or default parameters , 这是因为java缺省的库支持的key长度比较短，需要到oracle的网站上去下载一个支持更长key的库覆盖原有的库文件
<JAVA_HOME>/lib/securty/ 目录下的两个jar文件

local_policy.jar and US_export_policy.jar

搜索这个文件: Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files

下载页面(以JDK6为例)： http://www.oracle.com/technetwork/java/javase/downloads/jce-6-download-429243.html

package org.bouncycastle.openpgp.examples;

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.bcpg.CompressionAlgorithmTags;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openpgp.PGPCompressedData;
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.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.PGPSignatureList;
import org.bouncycastle.openpgp.PGPUtil;
import org.bouncycastle.openpgp.jcajce.JcaPGPObjectFactory;
import org.bouncycastle.openpgp.operator.jcajce.JcaKeyFingerprintCalculator;
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 files.
* 
* To encrypt a file: KeyBasedFileProcessor -e [-a|-ai] fileName publicKeyFile. 
* If -a is specified the output file will be "ascii-armored".
* If -i is specified the output file will be have integrity checking added.
* 
* To decrypt: KeyBasedFileProcessor -d fileName secretKeyFile passPhrase.
* 
* Note 1: this example will silently overwrite files, nor does it pay any attention to
* the specification of "_CONSOLE" in the filename. It also expects that a single pass phrase
* will have been used.
* 
* Note 2: if an empty file name has been specified in the literal data object contained in the
* encrypted packet a file with the name filename.out will be generated in the current working directory.
*/
public class KeyBasedFileProcessor
{
 private 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
 */
 private static void decryptFile(
 InputStream in,
 InputStream keyIn,
 char[] passwd,
 String defaultFileName)
 throws IOException, NoSuchProviderException
 {
 in = PGPUtil.getDecoderStream(in);

 try
 {
 JcaPGPObjectFactory pgpF = new JcaPGPObjectFactory(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), new JcaKeyFingerprintCalculator());

 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));

 JcaPGPObjectFactory plainFact = new JcaPGPObjectFactory(clear);

 Object message = plainFact.nextObject();

 while ( true ) {
 if (message instanceof PGPCompressedData)
 {
 PGPCompressedData cData = (PGPCompressedData)message;
 JcaPGPObjectFactory pgpFact = new JcaPGPObjectFactory(cData.getDataStream());

 message = pgpFact.nextObject();
 break;
 }

 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();
 break;
 }
 else if (message instanceof PGPOnePassSignatureList)
 {
 System.out.println("encrypted message contains a signed message - not literal data.");
 }
 else if (message instanceof PGPSignatureList)
 {
 System.out.println("encrypted message contains a signed message - not literal data.");
 }
 else
 {
 throw new PGPException("message is not a simple encrypted file - type unknown.");
 }
 message = plainFact.nextObject();
 }

 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();
 }
 }
 }

 private 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();
 }

 private static void encryptFile(
 OutputStream out,
 String fileName,
 PGPPublicKey encKey,
 boolean armor,
 boolean withIntegrityCheck)
 throws IOException, NoSuchProviderException
 {
 if (armor)
 {
 out = new ArmoredOutputStream(out);
 }

 try
 {
 byte[] bytes = PGPExampleUtil.compressFile(fileName, CompressionAlgorithmTags.ZIP);

 PGPEncryptedDataGenerator encGen = new PGPEncryptedDataGenerator(
 new JcePGPDataEncryptorBuilder(PGPEncryptedData.CAST5).setWithIntegrityPacket(withIntegrityCheck).setSecureRandom( new SecureRandom()).setProvider("BC"));

 encGen.addMethod( new JcePublicKeyKeyEncryptionMethodGenerator(encKey).setProvider("BC"));

 OutputStream cOut = encGen.open(out, bytes.length);

 cOut.write(bytes);
 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());

 if (args.length == 0)
 {
 System.err.println("usage: KeyBasedFileProcessor -e|-d [-a|ai] file [secretKeyFile passPhrase|pubKeyFile]");
 return;
 }

 if (args[0].equals("-e"))
 {
 if (args[1].equals("-a") || args[1].equals("-ai") || args[1].equals("-ia"))
 {
 encryptFile(args[2] + ".asc", args[2], args[3], true, (args[1].indexOf('i') > 0));
 }
 else if (args[1].equals("-i"))
 {
 encryptFile(args[2] + ".bpg", args[2], args[3], false, true);
 }
 else
 {
 encryptFile(args[1] + ".bpg", args[1], args[2], false, false);
 }
 }
 else if (args[0].equals("-d"))
 {
 decryptFile(args[1], args[2], args[3].toCharArray(), new File(args[1]).getName() + ".out");
 }
 else
 {
 System.err.println("usage: KeyBasedFileProcessor -d|-e [-a|ai] file [secretKeyFile passPhrase|pubKeyFile]");
 }
 }
}

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OpenPGP加密解密文件

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