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
   /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 com.test.test;

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();
        }
    
        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]");
  }

  }
  }