解密JWE时出错

Question

对于JWE解密这件事来说有点陌生。我有一个服务器，它执行JWE并根据服务器和客户端之间共享的密钥将其发送给客户端。

我正在使用Jose4j进行解密，并得到了这个错误

Java语言lang.NullPointerException:JWE的明文负载尚未设置。

我正在使用此链接中显示的示例代码，接收器部分

https://bitbucket.org/b_c/jose4j/wiki/JWE示例

我对服务器没有任何洞察力，只是编写客户端。我很困惑，如果paylaod本身没有来，或者那个框架正在试图解密。

感谢任何调试问题的指针

问候，阿拉文

Answer 1

JWE在获得纯文本负载之前需要2个级别的解密。

所以首先是JWE到JWS。然后在验证签名后从JWS到JWT。下面的代码将实现这一点。

  // That other party, the receiver, can then use JsonWebEncryption to decrypt the message.
        JsonWebEncryption receiverJwe = new JsonWebEncryption();

        // Set the compact serialization on new Json Web Encryption object
        //This is the received payload JWE payload 
        receiverJwe.setCompactSerialization(result.toString());


        // Symmetric encryption, like we are doing here, requires that both parties have the same key.
        // The key will have had to have been securely exchanged out-of-band somehow.
        receiverJwe.setKey(secretKeySpec);

        // Set the "alg" header, which indicates the key management mode for this JWE.
        // In this example we are using the direct key management mode, which means
        // the given key will be used directly as the content encryption key.
        //receiverJwe.setAlgorithmHeaderValue(KeyManagementAlgorithmIdentifiers.DIRECT);

        //receiverJwe.setEncryptionMethodHeaderParameter(ContentEncryptionAlgorithmIdentifiers.AES_128_CBC_HMAC_SHA_256);

        // Get the message that was encrypted in the JWE. This step performs the actual decryption steps.
        String jwsPayload = receiverJwe.getPlaintextString();

        // And do whatever you need to do with the clear text message.
        System.out.println("plaintext: " + jwsPayload);

        // Create a new JsonWebSignature object
        JsonWebSignature jws = new JsonWebSignature();

        jws.setCompactSerialization(jwsPayload);

        jws.setKey(secretKeySpec);

        boolean signatureVerified = jws.verifySignature();

        // Do something useful with the result of signature verification
        System.out.println("JWS Signature is valid: " + signatureVerified);

        // Get the payload, or signed content, from the JWS
        String payload = jws.getPayload();

        // Do something useful with the content
        System.out.println("JWS payload: " + payload);

Answer 2

只有在没有有效负载集的情况下，才会从getCompactSerialization（）方法引发该特定异常-getCompactSerialization（）是发送/加密端创建JWE的最后一步。如果你正在解密，你不应该这么叫。也许你在什么地方接到了一个意外的电话？否则，您使用的代码以及示例原始JWE值可能有助于解决问题（和键，如果这只是一个测试，您可以共享它们）。