using System;

using System.IO;

using System.Security.Cryptography;

using System.Text;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

         string originalText = "102";

​

        // Key for AES encryption

        string key = "ThisIsA16ByteKey";

​

        // Encrypt the text

        string encryptedText = EncryptAes(originalText, key);

​

        // Truncate the encrypted result to less than 10 characters (e.g., first 9 characters)

        string truncatedEncryptedText = RemoveSpecialSymbols(encryptedText.Substring(0, 9)).ToLower();

        Console.WriteLine("Original Text: " + originalText);

        Console.WriteLine("Truncated Encrypted Text: " + truncatedEncryptedText);

    }

    public static string EncryptAes(string plainText, string key)

    {

        using Aes aesAlg = Aes.Create();

        aesAlg.Key = Encoding.UTF8.GetBytes(key);

        aesAlg.Mode = CipherMode.ECB; // Use ECB mode for shorter ciphertext (not recommended for security)

        aesAlg.Padding = PaddingMode.PKCS7; // Padding mode

​

        ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, null); // No IV

​

        using MemoryStream msEncrypt = new MemoryStream();

        using CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write);

​

        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))

        {

            swEncrypt.Write(plainText);

        }

​

        byte[] encryptedBytes = msEncrypt.ToArray();

​

        // Convert the encrypted result to a Base64-encoded string

        return Convert.ToBase64String(encryptedBytes);

    }

     public static string RemoveSpecialSymbols(string input)

    {

        // Define a regular expression pattern to match specific special symbols

        string pattern = "[@#$!+/]";

​

        // Use Regex.Replace to remove matching characters

        string sanitized = Regex.Replace(input, pattern, string.Empty);

​

        return sanitized;

    }

}