java BouncyCastle pgp 加密解密文件

BouncyCastle 是 Java 平台上的一个加解密库，支持多种加密算法，包括 PGP 加解密。以下是使用 BouncyCastle 实现 PGP 加密解密文件的示例代码：

1. 加载 BouncyCastle Provider：

Security.addProvider(new BouncyCastleProvider());

2. 生成 PGP 密钥对：

PGPKeyPairGenerator kpg = new JcaPGPKeyPairGenerator().setProvider("BC").setAlgorithm(AsymmetricAlgorithmTags.RSA_GENERAL).setKeySize(2048);
PGPKeyPair kp = kpg.generate();

3. 导出公钥和私钥：

PGPPublicKeyRing publicKeyRing = new PGPPublicKeyRing(kp.getPublicKey().getEncoded(), new JcaKeyFingerprintCalculator());
PGPPublicKey publicKey = publicKeyRing.getPublicKey();
PGPPrivateKey privateKey = kp.getPrivateKey();

4. 加密文件：

// 创建加密器
PGPEncryptorBuilder builder = new JcePGPEncryptorBuilder(SymmetricKeyAlgorithmTags.AES_256).setSecureRandom(new SecureRandom());
builder.setProvider("BC");
PGPEncryptor encryptor = builder.build(publicKey);

// 创建输出流
File outputFile = new File("encrypted.pgp");
OutputStream outputStream = new FileOutputStream(outputFile);

// 创建压缩器
PGPCompressedDataGenerator compressor = new PGPCompressedDataGenerator(CompressionAlgorithmTags.ZIP);
OutputStream compressedOutputStream = compressor.open(outputStream);

// 创建签名器
PGPSignatureGenerator signatureGenerator = new PGPSignatureGenerator(new JcaPGPContentSignerBuilder(PublicKeyAlgorithmTags.RSA_GENERAL, HashAlgorithmTags.SHA256).setProvider("BC"));
signatureGenerator.init(PGPSignature.BINARY_DOCUMENT, privateKey);
signatureGenerator.generateOnePassVersion(false).encode(compressedOutputStream);

// 创建字节流加密器
PGPLiteralDataGenerator literalDataGenerator = new PGPLiteralDataGenerator();
OutputStream literalOutputStream = literalDataGenerator.open(compressedOutputStream, PGPLiteralData.BINARY, "filename", new Date(), new byte[1024]);

// 加密文件内容
File inputFile = new File("input.txt");
InputStream inputStream = new FileInputStream(inputFile);
byte[] buffer = new byte[1024];
int length;
while ((length = inputStream.read(buffer)) != -1) {
    literalOutputStream.write(buffer, 0, length);
}
inputStream.close();

// 关闭流
literalDataGenerator.close();
signatureGenerator.generate().encode(compressedOutputStream);
compressor.close();
encryptor.close();
outputStream.close();

5. 解密文件：

// 创建解密器
PGPObjectFactory factory = new JcaPGPObjectFactory(new FileInputStream("encrypted.pgp"));
PGPEncryptedDataList encryptedDataList = (PGPEncryptedDataList) factory.nextObject();
PGPPBEEncryptedData pbeEncryptedData = (PGPPBEEncryptedData) encryptedDataList.get(0);
PGPPrivateKey privateKey = findPrivateKey("userid", "password".toCharArray());
InputStream decryptedInputStream = pbeEncryptedData.getDataStream(new JcePBEDataDecryptorFactoryBuilder(new JcaPGPDigestCalculatorProviderBuilder().setProvider("BC").build()).setProvider("BC").build(privateKey));

// 创建签名校验器
PGPObjectFactory plainFactory = new JcaPGPObjectFactory(decryptedInputStream);
PGPOnePassSignatureList signatureList = (PGPOnePassSignatureList) plainFactory.nextObject();
PGPOnePassSignature signature = signatureList.get(0);
PGPPublicKey publicKey = findPublicKey(signature.getKeyID());
signature.init(new JcaPGPContentVerifierBuilderProvider().setProvider("BC"), publicKey);
PGPLiteralData literalData = (PGPLiteralData) plainFactory.nextObject();
InputStream literalInputStream = literalData.getInputStream();

// 校验签名
byte[] buffer = new byte[1024];
int length;
while ((length = literalInputStream.read(buffer)) != -1) {
    signature.update(buffer, 0, length);
}
if (signature.verify(((PGPSignatureList) plainFactory.nextObject()).get(0))) {
    System.out.println("Signature verified");
} else {
    System.out.println("Signature not verified");
}

// 读取文件内容
while ((length = literalInputStream.read(buffer)) != -1) {
    // 处理文件内容
}
literalInputStream.close();
decryptedInputStream.close();

其中，`findPrivateKey` 和 `findPublicKey` 方法根据指定的用户 ID 查找对应的私钥和公钥。在实际使用时，需要将用户 ID 和密钥信息存储在合适的位置，例如文件或数据库中，然后在程序中进行读取。