OpenPGP 號稱是世界上使用最廣泛的郵件加密標準.
OpenPGP is the most widely used email encryption standard in the world. ( http://www.openpgp.org/ )
這篇例子介紹如何使用這個標準進行文件的加密解密 (https://www.bouncycastle.org/latest_releases.html, 需要下載: bcprov-jdk15on-151.jar, bcpg-jdk15on-151.jar).
主要是使用bouncycastle提供的OpenPGP的庫來完成這個功能，參照了其提供的示例程序，進行了部分改動 (
Bouncy Castle 是一種用于 Java 平臺的開放源碼的輕量級密碼術包。它支持大量的密碼術算法，并提供 JCE 1.2.1 的實現。因為 Bouncy Castle 被設計成輕量級的，所以從 J2SE 1.4 到 J2ME（包括 MIDP）平臺，它都可以運行。它是在 MIDP 上運行的唯一完整的密碼術包。)1. 添加循環遍歷來查找第一個可用的message
2. 需要注意的是在main函數中的，
如果不添加這一句的話 Security.addProvider(new BouncyCastleProvider()); 程序運行中會報錯：No such Provider "BC"
3. 錯誤Exception in thread "main" java.security.InvalidKeyException: Illegal key size or default parameters , 這是因為java缺省的庫支持的key長度比較短，需要到oracle的網站上去下載一個支持更長key的庫覆蓋原有的庫文件
<JAVA_HOME>/lib/securty/ 目錄下的兩個jar文件
local_policy.jar and US_export_policy.jar
搜索這個文件: Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files
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.
* <p>
* To encrypt a file: KeyBasedFileProcessor -e [-a|-ai] fileName publicKeyFile.<br>
* If -a is specified the output file will be "ascii-armored".
* If -i is specified the output file will be have integrity checking added.
* <p>
* To decrypt: KeyBasedFileProcessor -d fileName secretKeyFile passPhrase.
* <p>
* 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.
* <p>
* 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]");
}
}
}
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