Java：使用Bouncy Castle进行PGP加密

Question

Java：使用Bouncy Castle进行PGP加密

5

我正在尝试使用PGP进行加密，我的加密方法成功地加密了输入字符串，但是当我尝试解密它以验证加密是否已正确完成时，字符串无法解密。

我尝试了两种方法：

第一种方法使用 FileOutputStream 写入加密的字符串，而第二种方法使用 ByteArrayOutputStream 。 FileOutputStream 创建一个文件，我可以使用Kleopatra解密它。但是我的要求只是获得一个加密的字符串（而非写入文件）。因此，当我尝试解密使用 ByteArrayOutputStream 接收到的加密字符串时，它不起作用。我尝试复制该字符串并通过Kleopatra中的“工具”>>“剪贴板”解密它，但“解密/验证”选项被禁用。我尝试手动将字符串写入文件和通过FileWriter类写入文件，但解密失败，并出现错误消息“文件包含证书，无法解密或验证”。
我认为只有直接由OutputStream创建的文件才能成功解密。但我确实需要检查加密的字符串。
非常感谢您提供任何帮助。

- Unnamed user

1个回答

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- Michael Fehr · Accepted Answer

下面是一段摘自《Java密码学：工具与技术》（作者为David Hook和Jon Eaves）源代码的完整示例。所有示例的完整源代码可以在这里下载：https://www.bouncycastle.org/java-crypto-tools-src.zip 这些示例展示了使用El Gamal或椭圆曲线进行私钥/公钥创建以及使用AES-256进行加密。在ecExample方法中，我添加了两行代码，将加密字符串保存到文件“pgp-encrypted-string.dat”，然后重新加载数据以解密文件并显示解密后的字符串。

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();
    }
}

这是简短输出：

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!

新增: 我现在理解你有一个类似于字符串的

This string needs an encryption

如果您想使用RSA PGP公钥对其进行加密：

并获取加密字符串

现在您想使用Kleoptatra在线（例如https://sela.io/pgp-en/）或使用RSA PGP私钥和密码123456在Java中解密此消息：

并获取解密后的字符串：

This string needs an encryption

在Java中进行加密/解密，幸运的是，在BouncyCastle Github-Repo中有可用的示例文件: 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)创建新的PGP-密钥对。使用生成的密钥，您可以使用KeyBasedFileProcessor.java和必要的PGPExampleUtil.java进行加密或解密。

我使用“-a testidentity 123456”的参数创建了RSA密钥文件，使用“-e -ai plaintext.txt rsa_pub.asc”进行加密，使用“-d plaintext.txt.asc rsa_secret.asc 123456”进行解密。