Question

鉴于我将KeySize设置为192，当我通过执行以下操作加密某些数据时：

 static void Main()
        {
            var querystrings = "dataToEncrypt";
            byte[] keyvalue = new byte[] { 241, 205, 121, 123, 109, 246, 247, 103, 31, 225, 167, 220, 247, 119, 247, 119, 78, 125, 127, 167, 156, 213, 230, 250, };
            byte[] ivvalue = new byte[] { 194, 177, 79, 213, 87, 46, 213, 189, 243, 169, 32, 13, 217, 62, 34, 170, };
            byte[] querystringBytes = Encoding.UTF8.GetBytes(querystrings);

            using (RijndaelManaged rijndaelManaged = new RijndaelManaged())
            {
                rijndaelManaged.BlockSize = 128;
                rijndaelManaged.KeySize = 192;
                rijndaelManaged.IV = ivvalue;
                rijndaelManaged.Key = keyvalue;
                rijndaelManaged.Padding = PaddingMode.PKCS7;
                rijndaelManaged.Mode = CipherMode.CBC;

                using (MemoryStream memoryStream = new MemoryStream())
                {
                    ICryptoTransform transform = rijndaelManaged.CreateEncryptor();
                    using (CryptoStream cryptoStream = new CryptoStream(memoryStream, transform, CryptoStreamMode.Write))
                    {
                        cryptoStream.Write(querystringBytes, 0, querystringBytes.Length);
                        cryptoStream.FlushFinalBlock();
                        var output = Convert.ToBase64String(memoryStream.ToArray());
                        Console.WriteLine($"{output}");
                        Console.ReadKey();
                    }
                }
            }
        }

数据加密，因为IV和加密密钥分别为128位和192位长。但是，如果我将加密密钥设置为128位长（为了参数，我们使用与IV相同的字节数组），即

 static void Main()
        {
            var querystrings = "dataToEncrypt";
            byte[] keyvalue = new byte[] { 194, 177, 79, 213, 87, 46, 213, 189, 243, 169, 32, 13, 217, 62, 34, 170, };
            byte[] ivvalue = new byte[] { 194, 177, 79, 213, 87, 46, 213, 189, 243, 169, 32, 13, 217, 62, 34, 170, };
            byte[] querystringBytes = Encoding.UTF8.GetBytes(querystrings);

            using (RijndaelManaged rijndaelManaged = new RijndaelManaged())
            {
                rijndaelManaged.BlockSize = 128;
                rijndaelManaged.KeySize = 192;
                rijndaelManaged.IV = ivvalue;
                rijndaelManaged.Key = keyvalue;
                rijndaelManaged.Padding = PaddingMode.PKCS7;
                rijndaelManaged.Mode = CipherMode.CBC;

                using (MemoryStream memoryStream = new MemoryStream())
                {
                    ICryptoTransform transform = rijndaelManaged.CreateEncryptor();
                    using (CryptoStream cryptoStream = new CryptoStream(memoryStream, transform, CryptoStreamMode.Write))
                    {
                        cryptoStream.Write(querystringBytes, 0, querystringBytes.Length);
                        cryptoStream.FlushFinalBlock();
                        var output = Convert.ToBase64String(memoryStream.ToArray());
                        Console.WriteLine($"{output}");
                        Console.ReadKey();
                    }
                }
            }
        }

这仍然会毫无例外地加密。我的问题是：

当我明确将KeySize设置为192时，KeySize在内部做了什么，因为它接受128位加密密钥？为什么没有例外？

Answer 1

RijndaelManaged类的Key和KeySize属性继承自基类SymmetricAlgorithm类。 MSDN Library中没有详细记录这些属性的精确行为，但是如果查看SymmetricAlgorithm source code，您将看到Key和KeySize属性相互交互，如下所示：

设置Key属性时，KeySize属性会自动设置为新密钥的长度（以位为单位）。
当您设置KeySize属性时，将清除现有密钥（并在下次访问密钥时自动生成新的随机密钥。）

因此，如果您正在设置Key属性，那么事先没有必要设置KeySize属性。

RijndaelManaged - 设置KeySize属性有什么作用？

1 个答案: