java实现gpg加密代码,让GPG解密工作在Java（Bouncy Castle）

以下是一个 Java 使用 Bouncy Castle 库实现 GPG 加密的示例代码：

import java.io.*;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.util.*;
import java.util.zip.*;

import org.bouncycastle.bcpg.*;
import org.bouncycastle.bcpg.attr.*;
import org.bouncycastle.openpgp.*;
import org.bouncycastle.openpgp.operator.*;
import org.bouncycastle.openpgp.operator.bc.*;

public class GpgEncrypt {
    public static void main(String[] args) throws Exception {
        Security.addProvider(new BouncyCastleProvider());

        String publicKeyPath = "/path/to/public/key.asc";
        String outputFilePath = "/path/to/output/file.gpg";
        String inputFilePath = "/path/to/input/file.txt";

        FileInputStream publicKeyInputStream = new FileInputStream(publicKeyPath);
        PGPPublicKey publicKey = readPublicKey(publicKeyInputStream);

        FileOutputStream outputStream = new FileOutputStream(outputFilePath);
        encryptFile(outputStream, inputFilePath, publicKey);

        outputStream.flush();
        outputStream.close();
        publicKeyInputStream.close();
    }

    private static PGPPublicKey readPublicKey(InputStream inputStream) throws IOException, PGPException {
        PGPObjectFactory pgpObjectFactory = new PGPObjectFactory(PGPUtil.getDecoderStream(inputStream));
        PGPPublicKeyRing publicKeyRing = (PGPPublicKeyRing) pgpObjectFactory.nextObject();
        PGPPublicKey publicKey = publicKeyRing.getPublicKey();
        if (publicKey == null) {
            throw new IllegalArgumentException("Public key not found in the key ring.");
        }
        return publicKey;
    }

    private static void encryptFile(OutputStream outputStream, String inputFilePath, PGPPublicKey publicKey) throws IOException, NoSuchProviderException, PGPException {
        PGPCompressedDataGenerator compressedDataGenerator = new PGPCompressedDataGenerator(CompressionAlgorithmTags.ZIP);
        PGPUtil.writeFileToLiteralData(compressedDataGenerator.open(outputStream), PGPLiteralData.BINARY, new File(inputFilePath));

        JcePGPDataEncryptorBuilder dataEncryptorBuilder = new JcePGPDataEncryptorBuilder(SymmetricKeyAlgorithmTags.AES_256).setSecureRandom(new SecureRandom());
        PGPEncryptedDataGenerator encryptedDataGenerator = new PGPEncryptedDataGenerator(dataEncryptorBuilder);
        encryptedDataGenerator.addMethod(new BcPublicKeyKeyEncryptionMethodGenerator(publicKey));

        OutputStream encryptedOutputStream = encryptedDataGenerator.open(compressedDataGenerator.open(outputStream), new byte[PGPUtil.BUFFER_SIZE]);
        compressedDataGenerator.close();
        OutputStream armoredOutputStream = new ArmoredOutputStream(encryptedOutputStream);
        armoredOutputStream.flush();
        armoredOutputStream.close();
        encryptedOutputStream.close();
    }
}

该代码使用 Bouncy Castle 库中的类实现了 GPG 的加密功能，具体实现方式如下：

1. 读取公钥：从指定的文件中读取 GPG 公钥，将其转换为 `PGPPublicKey` 实例。
2. 加密文件：使用 `PGPCompressedDataGenerator` 将要加密的文件进行 Zip 压缩，然后使用 `PGPEncryptedDataGenerator` 和 `BcPublicKeyKeyEncryptionMethodGenerator` 将压缩后的数据加密并写入输出流中。
3. 输出加密数据：使用 `ArmoredOutputStream` 将加密数据转换为 ASCII 码格式，并将其写入输出流中。

通过以上步骤，即可实现 GPG 加密并输出加密数据。同时，解密时也需要使用 Bouncy Castle 库中的类进行解密操作。