c# - 如何在 dotnet core 2.1 中使用 256 长 block 大小的 Rijndael 算法

Question

我正在尝试使用 RijndaelManaged 加密字符串，以便将其发送到第三方服务。我已经在旧版本的 .Net 框架(4.5、4.6.x)中实现了该过程，如下所示:

RijndaelManaged rm= new RijndaelManaged();
rm.KeySize = 256;
rm.BlockSize = 256;//causes exception in dotnet core 2.1
rm.Padding = PaddingMode.PKCS7;
rm.Key = Convert.FromBase64String(this.Key);
rm.IV = Convert.FromBase64String(this.IV);

var encrypt = rm.CreateEncryptor(rm.Key, rm.IV);

根据 documentation , RijndaelManaged 类可以与 BlockSize = 256 一起使用。但是，当代码在dotenet core 2.1中运行时，抛出异常:

System.PlatformNotSupportedException: BlockSize must be 128 in this implementation. at System.Security.Cryptography.RijndaelManaged.set_BlockSize(Int32 value)

更新

感谢@Access-Denied 的回复，根据this ，我注意到这可能是 dotnet 核心文档中的一个错误，我不能将 256 长的 BlockSize 与 RijndaelManaged 类一起使用。正如我提到的，加密数据将被发送到第三方服务。我必须使用带有 32 长 IV 的 Rijndael。我该如何处理？

Answer 1

最好的文档是源代码。根据他们的source code仅支持 128:

public override int BlockSize
{
    get { return _impl.BlockSize; }
    set
    {
        Debug.Assert(BlockSizeValue == 128);

        //Values which were legal in desktop RijndaelManaged but not here in this wrapper type
        if (value == 192 || value == 256)
            throw new PlatformNotSupportedException(SR.Cryptography_Rijndael_BlockSize);

        // Any other invalid block size will get the normal "invalid block size" exception.
        if (value != 128)
            throw new CryptographicException(SR.Cryptography_Rijndael_BlockSize);
    }
}

使用 BouncyCaSTLe.NetCore。在以下 link 处有可用的代码片段:

var keyBytes = password.GetBytes(Keysize / 8);
var engine = new RijndaelEngine(256);
var blockCipher = new CbcBlockCipher(engine);
var cipher = new PaddedBufferedBlockCipher(blockCipher, new Pkcs7Padding());
var keyParam = new KeyParameter(keyBytes);
var keyParamWithIV = new ParametersWithIV(keyParam, ivStringBytes, 0, 32);

cipher.Init(true, keyParamWithIV);
var comparisonBytes = new byte[cipher.GetOutputSize(cipherTextBytes.Length)];
var length = cipher.ProcessBytes(cipherTextBytes, comparisonBytes, 0);
cipher.DoFinal(comparisonBytes, length);