使用多个RSA公钥进行加密

Question

我正在为服务器编写发送电子邮件的模块。在客户端应用程序中，用户可以添加多个接收器，每个接收器都有自己的公钥。我想使用多个密钥加密附件。例如，如果我添加了3个接收者，那么附件应该用3个不同的公钥加密。我使用bouncy castle来实现这一点，但它只适用于加密过程中的第一个公钥。我的意思是只有第一个人可以使用自己的私钥解密，其余的都不起作用。我为每个键添加方法的代码如下所示：

PGPEncryptedDataGenerator encryptedDataGenerator = new PGPEncryptedDataGenerator(dataEncryptor);

for (PGPPublicKey publicKey : publicKeys) {
        encryptedDataGenerator.addMethod(new BcPublicKeyKeyEncryptionMethodGenerator(publicKey));
}

整个方法看起来像：

public File encryptFile(String fileName,
        boolean armor,
        boolean withIntegrityCheck) throws IOException,
        NoSuchProviderException,
        PGPException {
    Security.addProvider(new BouncyCastleProvider());

    ByteArrayOutputStream bOut = new ByteArrayOutputStream();

    PGPCompressedDataGenerator comData
            = new PGPCompressedDataGenerator(PGPCompressedData.UNCOMPRESSED);

    PGPUtil.writeFileToLiteralData(comData.open(bOut),
            PGPLiteralData.BINARY,
            new File(fileName));

    comData.close();

    BcPGPDataEncryptorBuilder dataEncryptor
            = new BcPGPDataEncryptorBuilder(PGPEncryptedData.AES_256);

    dataEncryptor.setWithIntegrityPacket(withIntegrityCheck);

    dataEncryptor.setSecureRandom(new SecureRandom());

    PGPEncryptedDataGenerator encryptedDataGenerator
            = new PGPEncryptedDataGenerator(dataEncryptor);

    for (PGPPublicKey publicKey : publicKeys) {
        encryptedDataGenerator.addMethod(new BcPublicKeyKeyEncryptionMethodGenerator(publicKey));
    }

    byte[] bytes = bOut.toByteArray();

    FileOutputStream localByteArrayOutputStream = new FileOutputStream(fileName);

    Object localObject = localByteArrayOutputStream;

    if (armor) {

        localObject = new ArmoredOutputStream((OutputStream) localObject);

    }

    OutputStream localOutputStream = encryptedDataGenerator.open((OutputStream) localObject,
            bytes.length);

    localOutputStream.write(bytes);

    localOutputStream.close();

    return new File(fileName);
}

谁能帮帮我，告诉我做错了什么？

谢谢你的帮助。

[编辑]这段代码有效，我加载多个键的方法有问题。

Answer 1

一年后我也有同样的问题。我希望你已经解决了你的问题。我在这里写我的解决方案，以防其他人有类似的问题。

你的加密代码没有问题。问题可能出在解密中。对于加密的数据对象，应使用存储在对象中的密钥id找到正确的密钥。我的解密过程如下所示：

private byte[] decryptWithKey(byte[] bytes, PGPSecretKey secKey, String pass)
        throws PGPException, IOException {
    PBESecretKeyDecryptor keyDec = new JcePBESecretKeyDecryptorBuilder(
            new JcaPGPDigestCalculatorProviderBuilder().setProvider("BC").build())
            .setProvider("BC").build(pass.toCharArray());
    ByteArrayOutputStream bout = new ByteArrayOutputStream();

    PGPPrivateKey privateKey = secKey.extractPrivateKey(keyDec);
    PublicKeyDataDecryptorFactory dec1 =
            new JcePublicKeyDataDecryptorFactoryBuilder().setProvider("BC").build(privateKey);
    JcaPGPObjectFactory objFact = new JcaPGPObjectFactory(bytes);
    PGPEncryptedDataList encList = (PGPEncryptedDataList) objFact.nextObject();

    PGPPublicKeyEncryptedData encD = null;
    for(Iterator<PGPPublicKeyEncryptedData> it = encList.iterator(); it.hasNext(); ) {
        PGPPublicKeyEncryptedData end = it.next();
        if (secKey.getKeyID() == end.getKeyID()) {
            encD = end;
            break;
        }
    }
    assert encD != null: "Cannot find encrypted data with key: "
            + Long.toHexString(secKey.getKeyID());
    InputStream in = encD.getDataStream(dec1);
    byte[] buf = new byte[BufferSize];
    for (int len; (len = in.read(buf)) >= 0; ) {
        bout.write(buf, 0, len);
    }
    bout.close();
    return bout.toByteArray();
}

密钥是查找加密对象的匹配密钥的for循环。