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当我尝试解密字符串时，Visual Studio 会抛出异常：System.Security.Cryptography.CryptographicException 并说用于解密的数据长度无效。当编译器在 RC2_Decrypt 方法中到达 cs.Close() 时出现异常。

static byte[] RC2_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
    {
        byte[] encryptedBytes = null;
        string salt = "D495560961CCCFE0";
        byte[] saltBytes = Encoding.UTF8.GetBytes(salt);
        using (MemoryStream msStream = new MemoryStream())
        {
            using (RC2CryptoServiceProvider RC2 = new RC2CryptoServiceProvider())
            {
                RC2.KeySize = 128;
                RC2.BlockSize = 64;
                var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
                RC2.Key = key.GetBytes(RC2.KeySize / 8);
                RC2.IV = key.GetBytes(RC2.BlockSize / 8);
                RC2.Mode = CipherMode.CBC;
                using (var cs = new CryptoStream(msStream, RC2.CreateEncryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
                    cs.Close();
                }
                encryptedBytes = msStream.ToArray();
            }
        }
        return encryptedBytes;
    }

static byte[] RC2_Decrypt(byte[] bytesToBeDecrypted, byte[] passwordBytes)
    {
        byte[] decryptedBytes = null;
        string salt = "D495560961CCCFE0";
        byte[] saltBytes = Encoding.UTF8.GetBytes(salt);
        using (MemoryStream msStream = new MemoryStream())
        {
            using (RC2CryptoServiceProvider RC2 = new RC2CryptoServiceProvider())
            {
                RC2.KeySize = 128;
                RC2.BlockSize = 64;
                var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
                RC2.Key = key.GetBytes(RC2.KeySize / 8);
                RC2.IV = key.GetBytes(RC2.BlockSize / 8);
                RC2.Mode = CipherMode.CBC;
                using (var cs = new CryptoStream(msStream, RC2.CreateDecryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(bytesToBeDecrypted, 0, bytesToBeDecrypted.Length);
                    cs.Close();
                }
                decryptedBytes = msStream.ToArray();
            }
        }
        return decryptedBytes;
    }

这里的例子我只是测试这些方法。因此，首先我尝试加密一个简单的字符串。

static void Main(string[] args)
    {
        string password = "770A8A65DA156D24EE2A093277530142";
        byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
        Console.WriteLine("Encrypting");
        string str = "Hello world";
        Console.WriteLine(EncString(str, password));
        byte[] encArray = Encoding.UTF8.GetBytes(str);
        Console.WriteLine(DecString(str, password));
        Console.ReadKey();
    }

我用于字符串加密的方法：

 static string EncString(string message, string password)
    {
        byte[] byresToBeEncrypted = Encoding.UTF8.GetBytes(message);
        byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
        byte[] bytesToBeEncrypted = RC2_Encrypt(byresToBeEncrypted, passwordBytes);
        string result = Convert.ToBase64String(byresToBeEncrypted);
        return result;
    }

static string DecString(string message, string password)
    {
        byte[] bytesToBeEncrypted = Encoding.UTF8.GetBytes(message);
        byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
        byte[] bytesToBeDecrypted = RC2_Decrypt(bytesToBeEncrypted, passwordBytes);
        string result = Encoding.UTF8.GetString(bytesToBeDecrypted);
        return result;
    }

那么这些方法可以加密和解密文本文件，这就是我所需要的。但我还有一个问题。为什么这不适用于简单的字符串变量？

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