java - java密码学中 'AGCM256-KW'的算法字符串是什么，用于Cipher.getInstance(String algo)？

Question

引用 this ，我必须使用算法AGCM256-KW进行加密。我正在使用 Java Cryptography，但没有找到任何这样的算法。我发现最接近的是 AES_256/GCM/NoPadding，但它没有 KW( key 包装)。

这是我的测试代码

    public void testEncryption(String algo) {
    String shared_secret = "LyQnklSrxsk3Ch2+AHi9HoDW@//x1LwM123QP/ln";
    try {

        // Step 1 - Create SHA-256 digest of the shared key
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        byte[] digest = md.digest(shared_secret.getBytes("UTF-8"));

        // Step 2 - generate a 256 bit Content Encryption Key(CEK)
        KeyGenerator kg = KeyGenerator.getInstance("AES");
        kg.init(256);
        SecretKey cek = kg.generateKey();

        // Step 3 - encrypt the CEK using 256 bit digest generated in Step 1
        // and 96 bit random IV. Algorithm should be

        // random 96 bit Initialize Vector
        SecureRandom random = new SecureRandom();
        // byte iv[] = new byte[96];
        // random.nextBytes(iv);
        byte iv[] = random.generateSeed(96);
        System.out.println("IV: " + toBase64(iv) + " length: " + iv.length);
        IvParameterSpec ivspec = new IvParameterSpec(iv);
        GCMParameterSpec gspec = new GCMParameterSpec(96, iv);

        // encrypt
        Cipher cipher = Cipher.getInstance(algo);
        System.out.println(String.format("CEK Cipher alg:%S provider:%S", cipher.getAlgorithm(),
                cipher.getProvider().getName()));

        cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(digest, "AES"), gspec);
        byte[] result = cipher.doFinal(cek.getEncoded());

        System.out.println(String.format("Encrypted CEK :%S", toBase64(result)));

    } catch (NoSuchAlgorithmException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (InvalidKeyException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (InvalidAlgorithmParameterException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (NoSuchPaddingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalBlockSizeException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (BadPaddingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

更新 1我想我可以使用 jose4j具有 JWE 的 API 的库.

Answer 1

是的，Visa token 服务似乎正在使用 JWE(现在为 RFC 7516)，因此您可以为此使用 jose4j。下面是一些示例代码，展示了使用 A256GCMKW 和 AGCM256 使用 JWE 对某些内容进行加密和解密:

    // shared secret hashed to key from your example
    String shared_secret = "LyQnklSrxsk3Ch2+AHi9HoDW@//x1LwM123QP/ln";
    MessageDigest md = MessageDigest.getInstance("SHA-256");
    byte[] digest = md.digest(shared_secret.getBytes("UTF-8"));

    JsonWebEncryption jwe = new JsonWebEncryption();

    // A256GCMKW for key wrap
    jwe.setAlgorithmHeaderValue(KeyManagementAlgorithmIdentifiers.A256GCMKW);

    // A256GCM for content encryption
    jwe.setEncryptionMethodHeaderParameter(ContentEncryptionAlgorithmIdentifiers.AES_256_GCM);

    // the key (from above)
    jwe.setKey(new SecretKeySpec(digest, "AES"));

    // whatever content you want to encrypt
    jwe.setPayload("some important content to be encrypted and integrity protected");

    // Produce the JWE compact serialization, which is where the actual encryption is done.
    // The JWE compact serialization consists of five base64url encoded parts
    // combined with a dot ('.') character in the general format of
    // <header>.<encrypted key>.<initialization vector>.<ciphertext>.<authentication tag>
    String serializedJwe = jwe.getCompactSerialization();


    // Do something with the JWE. Like send it to some other party over the clouds
    // and through the interwebs.
    System.out.println("JWE compact serialization: " + serializedJwe);

    // 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
    receiverJwe.setCompactSerialization(serializedJwe);

    // 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(new SecretKeySpec(digest, "AES"));

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

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