EAX中带有JCE-MAC检查的AES/EAX加密失败

Question

我正在尝试使用AES/EAX/Nopadding执行加密/解密。由于EAX似乎没有BouncyCastle可用，所以BC被添加为提供程序。

@NotNull
@Override
public byte[] encrypt(@NotNull Key key, @NotNull byte[] plain, @Nullable byte[] authentication) throws CryptoException {
    try {
        final AesEaxKey aesEaxKey = (AesEaxKey) key;
        final Cipher cipher = Cipher.getInstance(getCipherAlgorithm(), BouncyCastleProvider.PROVIDER_NAME);
        final byte[] cipherText = new byte[getIvSize(aesEaxKey) + plain.length + getTagSize()];
        final byte[] iv = randomIv(aesEaxKey);

        System.arraycopy(iv, 0, cipherText, 0, getIvSize(aesEaxKey));
        cipher.init(Cipher.ENCRYPT_MODE, aesEaxKey, getParameterSpec(iv));

        if (authentication != null && authentication.length != 0) {
            cipher.updateAAD(authentication);
        }

        cipher.doFinal(plain, 0, plain.length, cipherText, getIvSize(aesEaxKey));
        return cipherText;
    } catch (NoSuchPaddingException | NoSuchAlgorithmException | InvalidAlgorithmParameterException | NoSuchProviderException |
            InvalidKeyException | BadPaddingException | IllegalBlockSizeException | ShortBufferException e) {
        throw new CryptoException(e.getMessage(), e);
    }
}

@NotNull
@Override
public byte[] decrypt(@NotNull Key key, @NotNull byte[] cipherText, @Nullable byte[] authentication) throws CryptoException {
    try {
        final AesEaxKey aesEaxKey = (AesEaxKey) key;
        final Cipher cipher = Cipher.getInstance(getCipherAlgorithm(), BouncyCastleProvider.PROVIDER_NAME);
        cipher.init(Cipher.DECRYPT_MODE, aesEaxKey, getParameterSpec(cipherText, 0, getIvSize(aesEaxKey)));
        if (authentication != null && authentication.length != 0) {
            cipher.updateAAD(authentication);
        }
        return cipher.doFinal(cipherText, getIvSize(aesEaxKey), cipherText.length - getIvSize(aesEaxKey));
    } catch (NoSuchPaddingException | NoSuchAlgorithmException | InvalidKeyException | NoSuchProviderException |
            InvalidAlgorithmParameterException | IllegalBlockSizeException | BadPaddingException e) {
        throw new CryptoException(e.getMessage(), e);
    }
}

null

我有一个AES/GCM/nopadding的实现，它使用了同样的代码，工作得很好。

我做错了什么？

Answer 1

EAX等AEAD模式需要更复杂的AlgorithmParameterSpec，因为必须指定nonce（又名IV）和以比特为单位的标记长度。Java从1.7开始就为GCM密码提供了一个GCMParameterSpec。EAX模式需要相同的数据，显然Bouncycastle提供程序也将为EAX模式使用GCMParameterSpec。

注意，对于GCMParameterSpec，标记长度是以位为单位指定的，而为了调整数组的大小，标记长度需要以字节为单位指定。