How to do the Encrypted Data Is Converted to the UrlEncoded Formation

An example of how you can encrypt data using the AesManaged class and then URL-encode the resulting ciphertext:

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using System.Web;

namespace ExampleNamespace
{
    public class ExampleClass
    {
        private const string EncryptionKey = "YourEncryptionKey"; // Replace with your own key

        public static string EncryptAndUrlEncode(string plainText)
        {
            byte[] iv;
            byte[] encryptedData;

            using (var aes = new AesManaged())
            {
                aes.Key = Encoding.UTF8.GetBytes(EncryptionKey);
                aes.GenerateIV();

                using (var encryptor = aes.CreateEncryptor())
                {
                    using (var memoryStream = new MemoryStream())
                    {
                        using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
                        {
                            var data = Encoding.UTF8.GetBytes(plainText);
                            cryptoStream.Write(data, 0, data.Length);
                            cryptoStream.FlushFinalBlock();
                            encryptedData = memoryStream.ToArray();
                            iv = aes.IV;
                        }
                    }
                }
            }

            var encodedData = HttpServerUtility.UrlTokenEncode(encryptedData);
            var encodedIv = HttpServerUtility.UrlTokenEncode(iv);

            return $"{encodedData}.{encodedIv}";
        }
    }
}

In this example, EncryptionKey is the key that will be used to encrypt the data. You should replace this value with your own key. To use this method, simply call the EncryptAndUrlEncode method with your plaintext data as the parameter, like this:

var plainText = "Hello, world!";
var encryptedAndEncodedData = ExampleClass.EncryptAndUrlEncode(plainText);

The resulting value of encryptedAndEncodedData will be a URL-encoded string containing the encrypted ciphertext and IV, separated by a dot (.).

To convert encrypted data to the URL-encoded format in ASP.NET, you can use the HttpUtility.UrlEncode method. See the code snippet. 

string encryptedData = "example encrypted data";
string urlEncodedData = HttpUtility.UrlEncode(encryptedData);

In this example, encryptedData is the encrypted data that you want to encode, and urlEncodedData is the resulting URL-encoded string. URL encoding is a form of data transformation that is used to convert certain characters in a string to a format that can be safely transmitted in a URL. This is useful when transmitting data between web pages or when passing data to a server via a URL query string. However, URL encoding is not a form of encryption and should not be relied on for security purposes. If you need to securely transmit sensitive data over a network, you should use a secure protocol such as HTTPS or implement proper encryption and decryption methods.

Check this.

// Convert the encrypted data to URL-encoded format
string encryptedData = "your encrypted data";
string encodedData = Server.UrlEncode(encryptedData);

/ Append the encoded data to the URL
string url = "https://example.com?data=" + encodedData;