问题：

Java：使用Bouncy Castle的PGP加密

袁志专

2023-03-14

我正在尝试使用PGP实现加密，我的encrypt方法成功地加密了输入字符串，但当我尝试解密它以验证加密是否正确时，字符串没有被解密。

我尝试了两种方法：

我假设只有直接由OutputStream创建的文件能够成功解密。但我必须真的检查加密字符串。

如有任何帮助，我们将不胜感激。

诸葛皓

2023-03-14

下面的完整示例摘自David Hook和Jon Eaves的“Java密码学：工具和技术”一书的源代码。包含所有示例的完整源代码可在以下网址获得：https://www.bouncycastle.org/java-crypto-tools-src.zip

示例显示了使用El Gamal或椭圆曲线创建私钥/公钥以及使用AES-256加密。在ecExample-method中，我添加了两行代码，将加密的字符串保存到文件“pgp-encrypted-string.dat”中，然后重新加载数据以对文件进行解密并显示解密的字符串。

import org.bouncycastle.bcpg.SymmetricKeyAlgorithmTags;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openpgp.*;
import org.bouncycastle.openpgp.jcajce.JcaPGPObjectFactory;
import org.bouncycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
import org.bouncycastle.openpgp.operator.jcajce.JcaPGPKeyPair;
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.Strings;
import org.bouncycastle.util.io.Streams;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;
import java.security.Security;
import java.security.spec.ECGenParameterSpec;
import java.util.Date;

public class PGPEncryptionExampleForSO
{
     /**
     * Create an encrypted data blob using an AES-256 session key and the
     * passed in public key.
     *
     * @param encryptionKey the public key to use.
     * @param data the data to be encrypted.
     * @return a PGP binary encoded version of the encrypted data.
     */
    public static byte[] createEncryptedData(
        PGPPublicKey encryptionKey,
        byte[] data)
        throws PGPException, IOException
    {
        PGPEncryptedDataGenerator encGen = new PGPEncryptedDataGenerator(
            new JcePGPDataEncryptorBuilder(SymmetricKeyAlgorithmTags.AES_256)
                .setWithIntegrityPacket(true)
                .setSecureRandom(new SecureRandom()).setProvider("BC"));
        encGen.addMethod(
            new JcePublicKeyKeyEncryptionMethodGenerator(encryptionKey)
                .setProvider("BC"));
        ByteArrayOutputStream encOut = new ByteArrayOutputStream();
        // create an indefinite length encrypted stream
        OutputStream cOut = encGen.open(encOut, new byte[4096]);
        // write out the literal data
        PGPLiteralDataGenerator lData = new PGPLiteralDataGenerator();
        OutputStream pOut = lData.open(
            cOut, PGPLiteralData.BINARY,
            PGPLiteralData.CONSOLE, data.length, new Date());
        pOut.write(data);
        pOut.close();
        // finish the encryption
        cOut.close();
        return encOut.toByteArray();
    }

    /**
     * Extract the plain text data from the passed in encoding of PGP
     * encrypted data. The routine assumes the passed in private key
     * is the one that matches the first encrypted data object in the
     * encoding.
     *
     * @param privateKey the private key to decrypt the session key with.
     * @param pgpEncryptedData the encoding of the PGP encrypted data.
     * @return a byte array containing the decrypted data.
     */
    public static byte[] extractPlainTextData(
        PGPPrivateKey privateKey,
        byte[] pgpEncryptedData)
        throws PGPException, IOException
    {
        PGPObjectFactory pgpFact = new JcaPGPObjectFactory(pgpEncryptedData);
        PGPEncryptedDataList encList = (PGPEncryptedDataList)pgpFact.nextObject();
        // find the matching public key encrypted data packet.
        PGPPublicKeyEncryptedData encData = null;
        for (PGPEncryptedData pgpEnc: encList)
        {
            PGPPublicKeyEncryptedData pkEnc
                = (PGPPublicKeyEncryptedData)pgpEnc;
            if (pkEnc.getKeyID() == privateKey.getKeyID())
            {
                encData = pkEnc;
                break;
            }
        }
        if (encData == null)
        {
            throw new IllegalStateException("matching encrypted data not found");
        }
        // build decryptor factory
        PublicKeyDataDecryptorFactory dataDecryptorFactory =
            new JcePublicKeyDataDecryptorFactoryBuilder()
                .setProvider("BC")
                .build(privateKey);
        InputStream clear = encData.getDataStream(dataDecryptorFactory);
        byte[] literalData = Streams.readAll(clear);
        clear.close();
        // check data decrypts okay
        if (encData.verify())
        {
            // parse out literal data
            PGPObjectFactory litFact = new JcaPGPObjectFactory(literalData);
            PGPLiteralData litData = (PGPLiteralData)litFact.nextObject();
            byte[] data = Streams.readAll(litData.getInputStream());
            return data;
        }
        throw new IllegalStateException("modification check failed");
    }

    private static void elgamalExample()
        throws Exception
    {
        byte[] msg = Strings.toByteArray("Hello, world!");
        KeyPairGenerator kpGen = KeyPairGenerator.getInstance("DH", "BC");
        kpGen.initialize(2048);
        KeyPair kp = kpGen.generateKeyPair();
        PGPKeyPair elgKp = new JcaPGPKeyPair(
            PGPPublicKey.ELGAMAL_ENCRYPT, kp, new Date());
        byte[] encData = createEncryptedData(elgKp.getPublicKey(), msg);
        byte[] decData = extractPlainTextData(elgKp.getPrivateKey(), encData);
        System.out.println("elgamal encryption msg length: " + msg.length + " enc.length: " + encData.length + " dec.length: " + decData.length);
        System.out.println(Strings.fromByteArray(decData));
    }

    private static void ecExample()
        throws Exception
    {
        byte[] msg = Strings.toByteArray("Hello, world!");
        KeyPairGenerator kpGen = KeyPairGenerator.getInstance("EC", "BC");
        kpGen.initialize(new ECGenParameterSpec("P-256"));
        KeyPair kp = kpGen.generateKeyPair();
        PGPKeyPair ecdhKp = new JcaPGPKeyPair(PGPPublicKey.ECDH, kp, new Date());
        byte[] encData = createEncryptedData(ecdhKp.getPublicKey(), msg);
        // save encrypted string
        Files.write(Paths.get("pgp-encrypted-string.dat"), encData);
        // load encrypted string
        byte[] encDataLoad = Files.readAllBytes(Paths.get("pgp-encrypted-string.dat"));
        byte[] decData = extractPlainTextData(ecdhKp.getPrivateKey(), encDataLoad);
        System.out.println("ec encryption msg length: " + msg.length + " enc.length: " + encData.length + " dec.length: " + decData.length);
        System.out.println(Strings.fromByteArray(decData));
    }

    public static void main(String[] args)
        throws Exception
    {
        Security.addProvider(new BouncyCastleProvider());
        // you need the two files bcpg-jdk15on-165.jar and bcprov-jdk15to18-165.jar to run the example
        System.out.println("Example from Java Cryptography: Tools and Techniques by David Hook & Jon Eaves");
        System.out.println("get source files: https://www.bouncycastle.org/java-crypto-tools-src.zip");
        elgamalExample();
        ecExample();
    }
}

这是短输出：

Example from Java Cryptography: Tools and Techniques by David Hook & Jon Eaves
get source files: https://www.bouncycastle.org/java-crypto-tools-src.zip
elgamal encryption msg length: 13 enc.length: 601 dec.length: 13
Hello, world!
ec encryption msg length: 13 enc.length: 200 dec.length: 13
Hello, world!

This string needs an encryption

现在您希望使用Kleoptatra在线（例如https://sela.io/pgp-en/）或使用RSA pgp私钥和密码123456在Java中解密该消息：

并获取解密的字符串：

This string needs an encryption

要在Java中加密/解密，幸运的是，BouncyCastle github-repo中提供了示例文件：https://github.com/bcgit/bc-java/blob/master/pg/src/main/Java/org/BouncyCastle/openpgp/examples/。您可能需要使用RSA（RSAKeyPairGenerator.java）或ElGamal（DSAELGamalKeyRingGenerator.java）创建一个新的PGP-keypair。使用生成的密钥，您可以使用KeyBasedFileProcessor.java和必要的PGPExampleUtil.java加密或解密。

我用“-a testidentity 123456”作为参数创建了RSA密钥文件，加密用“-e-ai plaintext.txt rsa_pub.asc”完成，解密用“-d plaintext.txt.asc rsa_secret.asc 123456”完成。

Java：使用Bouncy Castle的PGP加密

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