using System;

using System.Security.Cryptography;

using System.Text;

​

namespace EncryptionExample

{

    class Program

    {

        static void Main(string[] args)

        {

            // Generate a random encryption key

            byte[] key = new byte[32]; // 256-bit key

            using RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();

            rng.GetBytes(key);

​

            // Encrypt an integer number

            int originalNumber = 12345;

            byte[] encryptedData = EncryptInteger(originalNumber, key);

​

            // Base64 encode the encrypted data

            string encodedData = Convert.ToBase64String(encryptedData);

​

            // URL encode the encoded data

            string urlEncodedData = UrlEncode(encodedData);

​

            // URL decode the encoded data

            string urlDecodedData = UrlDecode(urlEncodedData);

​

            // Base64 decode the decoded data

            byte[] decodedData = Convert.FromBase64String(urlDecodedData);

​

            // Decrypt the decrypted data

            int decryptedNumber = DecryptInteger(decodedData, key);

​

            // Print the encryption key

            Console.WriteLine("Encryption key:");

            Console.WriteLine(Convert.ToBase64String(key));

​

            Console.WriteLine($"Original number: {originalNumber}");

            Console.WriteLine($"Encrypted data (base64): {encodedData}");

            Console.WriteLine($"Encoded and URL encoded data: {urlEncodedData}");

            Console.WriteLine($"URL decoded and base64 decoded data: {urlDecodedData}");

            Console.WriteLine($"Decrypted number: {decryptedNumber}");

        }

​

        static byte[] EncryptInteger(int number, byte[] key)

        {

            byte[] iv = new byte[16]; // 128-bit IV

            using Aes aes = Aes.Create();

            aes.Key = key;

            aes.IV = iv;

​

            using var encryptor = aes.CreateEncryptor();

            byte[] dataToEncrypt = BitConverter.GetBytes(number);

            byte[] encryptedData = encryptor.TransformFinalBlock(dataToEncrypt, 0, dataToEncrypt.Length);

​

            return encryptedData;

        }

​

        static int DecryptInteger(byte[] encryptedData, byte[] key)

        {

            byte[] iv = new byte[16]; // 128-bit IV

            using Aes aes = Aes.Create();

            aes.Key = key;

            aes.IV = iv;

​

            using var decryptor = aes.CreateDecryptor();

            byte[] decryptedData = decryptor.TransformFinalBlock(encryptedData, 0, encryptedData.Length);

            int decryptedNumber = BitConverter.ToInt32(decryptedData);

​

            return decryptedNumber;

        }

​

        static string UrlEncode(string text)

        {

            return Uri.EscapeDataString(text);

        }

​

        static string UrlDecode(string text)

        {

            return Uri.UnescapeDataString(text);

        }

    }

}

​